Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses

Genetic effects on controlling stripe rust resistance were determined in two wheat crosses, Bakhtawar-92 x Frontana (cross 1) and Inqilab-91 x Fakhre Sarhad (cross 2) using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance.

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Datum:2009
Hauptverfasser: Irfaq, M., Mir Ajab, Ma Hongxiang, Gss Khattak
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Veröffentlicht: Інститут клітинної біології та генетичної інженерії НАН України 2009
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Zitieren:Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses / M. Irfaq, Mir Ajab, Ma Hongxiang, Gss Khattak // Цитология и генетика. — 2009. — Т. 43, № 3. — С. 25-38. — Бібліогр.: 25 назв. — англ.

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spelling irk-123456789-666512017-12-02T22:39:29Z Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses Irfaq, M. Mir Ajab Ma Hongxiang Gss Khattak Оригинальные работы Genetic effects on controlling stripe rust resistance were determined in two wheat crosses, Bakhtawar-92 x Frontana (cross 1) and Inqilab-91 x Fakhre Sarhad (cross 2) using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance. Генетические эффекты контроля устойчивости к желтой ржавчине злаков были определены в двух скрещиваниях пшеницы Bakhtawar-92 x Frontana (скрещивание 1) и Inquilab-91 x Fakhre-Sarhad (скрещивание 2) с использованием Area Under Disease Progress Curve (AUDPC) для измерения устойчивости. Генетичні ефекти контролю стійкості до жовтої іржі злаків були визначені в двох схрещуваннях пшениці Bakhtawar-92 x Frontana (схрещування 1) и Inquilab-91 x Fakhre-Sarhad (схрещування 2) з використанням Area Under Disease Progress Curve (AUDPC) для вимірювання стійкості. 2009 Article Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses / M. Irfaq, Mir Ajab, Ma Hongxiang, Gss Khattak // Цитология и генетика. — 2009. — Т. 43, № 3. — С. 25-38. — Бібліогр.: 25 назв. — англ. 0564-3783 http://dspace.nbuv.gov.ua/handle/123456789/66651 en Цитология и генетика Інститут клітинної біології та генетичної інженерії НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
topic Оригинальные работы
Оригинальные работы
spellingShingle Оригинальные работы
Оригинальные работы
Irfaq, M.
Mir Ajab
Ma Hongxiang
Gss Khattak
Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
Цитология и генетика
description Genetic effects on controlling stripe rust resistance were determined in two wheat crosses, Bakhtawar-92 x Frontana (cross 1) and Inqilab-91 x Fakhre Sarhad (cross 2) using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance.
format Article
author Irfaq, M.
Mir Ajab
Ma Hongxiang
Gss Khattak
author_facet Irfaq, M.
Mir Ajab
Ma Hongxiang
Gss Khattak
author_sort Irfaq, M.
title Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
title_short Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
title_full Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
title_fullStr Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
title_full_unstemmed Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses
title_sort assessment of genes controlling area under disease progress curve (audpc) for stripe rust (p. striiformis f. sp. tritici) in two wheat (triticum aestivum l.) crosses
publisher Інститут клітинної біології та генетичної інженерії НАН України
publishDate 2009
topic_facet Оригинальные работы
url http://dspace.nbuv.gov.ua/handle/123456789/66651
citation_txt Assessment of genes controlling Area Under Disease Progress Curve (AUDPC) for stripe rust (P. striiformis f. sp. Tritici) in two wheat (Triticum aestivum L.) crosses / M. Irfaq, Mir Ajab, Ma Hongxiang, Gss Khattak // Цитология и генетика. — 2009. — Т. 43, № 3. — С. 25-38. — Бібліогр.: 25 назв. — англ.
series Цитология и генетика
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AT mahongxiang assessmentofgenescontrollingareaunderdiseaseprogresscurveaudpcforstriperustpstriiformisfsptriticiintwowheattriticumaestivumlcrosses
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fulltext M. IRFAQ 1, MIR AJAB 2, MA HONGXIANG 3, GSS KHATTAK 1 1 Crop Breeding Division, Nuclear Institute for Food and Agriculture (NIFA), Peshawar, N.W.F.P., Pakistan 2 Faculty of Plant Science, Department of Biological Sciences, Quaid�i�Azam University, Islamabad, Pakistan 3 Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, P.R. China ASSESSMENT OF GENES CONTROLLING AREA UNDER DISEASE PROGRESS CURVE (AUDPC) FOR STRIPE RUST (P. STRIIFORMIS F. SP. TRITICI) IN TWO WHEAT (TRITICUM AESTIVUM L.) CROSSES Genetic effects on controlling stripe rust resistance were determined in two wheat crosses, Bakhtawar�92 � Frontana (cross 1) and Inqilab�91 � Fakhre Sarhad (cross 2) using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance. The resistant and susceptible genotypes for crosses were identified by initial assessment of 45 wheat accessions for stripe rust resistance. Mixed inheritance model was applied to the data analysis of six basic populations P1, F1, P2, B1, B2, and F2 in the crosses. The results indicated that AUDPC in cross 1 was controlled by two major genes with additive�dominance epistatic effect plus polygenes with addi� tive�dominance epistatic effects (model E). Whereas in case of cross 2, it was under the control of two major genes with addi� tive�dominance epistatic effect plus additive�dominant poly� genes (model E�1). Additive effect was predominant then all other types of genetic effects suggesting the delay in selection for resistance till maximum positive genes are accumulated in the individuals of subsequent generations. Occurrence of transgressive segregants for susceptibility and resistance indi� cated the presence of resistance as well as some negative genes for resistance in the parents. The major gene heritability was higher than the polygene heritability in B1, B2 and F2 for the crosses. The major gene as well as the polygene heritability was ranging from 48.99 to 87.12 % and 2.26 and 36.80 % for the two crosses respectively. The highest phenotypic variations in AUDPC (2504.10 to 5833.14) for segregating progenies (BC1, BC2 and F2) represent that the character was highly influenced by the environment. Introduction. Stripe (yellow) rust caused by a fungus Puccinia striiformis f. sp. tritici, is a major disease of wheat word wide especially in moist and cool environments [1]. The disease appeared in epidemic form in Pakistan during the year 2004– 2005 because of the environmental conditions made highly conducive through tsunami effect. Grain yield losses from 20 to 60 % in susceptible wheat cultivars have been reported in case of severe out break of the disease during ear emergence [2]. Cultivation of genetically resistant cultivars is the effective measure to control the disease. Race spe� cific or vertical resistance has remained no longer effective because of the evolution and population diversity of new virulent pathotypes [3]. Durable resistance controlled by the combined effect of both major and minor genes is desired to control the disease for longer time in an environment con� ducive for the disease development. This requires the availability of well known resistant genetic resources, a better understanding of the host�pathogen inter� action and suitable techniques to utilize the desired genes. Adult plant resistance is most often desired by wheat breeders in order to avoid/reduce yield losses caused by the disease at adult plant stage [4]. Identification of genetically variable lines with respect to stripe rust resistance is of great help to select the parents for cross combination so as to pyramid genes from different resistant resources in to a single genotype with durable resistance. The aim of the present study was to identify genotypes with high level of resistance to stripe rust, transfer� ring of resistant genes from resistant to suitable geno� type through successful cross combination and to study the genetic basis of resistance in wheat by using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance. Materials and methods. Field evaluation of germplasm for AUDPC at adult plant stage. Seeds of 45 bread wheat genotypes differing in their genetic make up and origin were collected from different sources viz Pakistan, India, CIMMYT and Brazil. Twenty of these genotypes were belonging from Pakistan, fifteen from CIMMYT, Mexico, nine from India and 1 from Brazil. The accessions were planted as stripe rust screening nursery in two replications in two�meter�long rows per entry with 20 seeds per row in randomized complete block design at experimental farm of Nuclear Institute for Food and Agriculture (NIFA), Peshawar, Pakistan during rabi, 2003–2004. The plot size per entry in each set was kept 1.2 m2. ІSSN 0564–3783. Цитология и генетика. 2009. № 4 25 © M. IRFAQ, MIR AJAB, MA HONGXIANG, GSS KHATTAK, 2009 Creation of artificial epiphytotic condition in the nursery. Each entry of the nursery was bordered with a susceptible check of ‘Morocco’ as a spreader of stripe rust. Artificial stripe rust epiphytotic condi� tions was created in the field as referred by [5], inoc� ulated the nursery material at tillering stages in late afternoon with uniform spray of spore suspension containing mixture of urediospores of different stripe rust (Puccinia striiformis) races prevalent in Pakis� tan, through turbo air sprayer at the end of February, 2004. Urediospore mixture was obtained from Na� tional Wheat Diseases Research Program (NWDRP) at National Agriculture Research Center (NARC) Islamabad, probably consisting of 67E0, CYR32, 78S84, 110E143A, 230E150, 230E134, Pst 106, E139A and 110E143A pathotypes. These races has virulence formula against the stripe rust resistant genes as Yr1,2,3,4, 5, 6, 7, 8, 9, 10, 15, 17, YrA, and Yr27 [1, 6]. Tween 20 was added in fresh tap water by dissolving urediospores at a rate of 1 gram/litter with approximate concentration of 30000/ml in the suspension as determined by haemocytometer. The nursery material was covered with plastic sheets to keep the moisture for making conditions conducive to spore germination and to avoid washing of spores by dew drops. For spore multiplication and disease development, plane water in the late afternoon was sprayed on to the nursery material with the intervals of two days (for a period of fortnight) until the dis� ease symptoms appeared in the field. Methodology for disease scoring and determining AUDPC. After successful disease development, data for rust severity (percentage of leaf area with symptoms) was recorded on the top three leaves of five randomly selected plants from each accession on 0–9 points rating scale with little modification to those of [7], as suggested by [8] (Table 1). Second reading of all selected plants was recorded after seven days of the first reading. Observations on response and severity of stripe rust were record� ed according to [9]. Rust severity was determined by visual observation and recorded from 0 to 100 % of rust infection on 5 selected plants with in each population according to the modified Cobb scale [10]. For recording correct readings of sever� ity up to interval 2 on individual plants, the term trace (T) was used below 5 % severity. A five per� cent interval was used from 5 to 20 percent severi� ty and 10 percent intervals for higher readings. The response of individual plants within each popula� tion to the type of stripe rust infection was record� ed in Table 2. Severity and reaction were recorded together with severity first. The Coefficient of infection (CI) for the rust was calculated in the manner used in CIMMYT and IRN (USDA) i.e., by multiplying the response value with the intensi� ty of infection in percent. Average coefficient of infection (ACI) was derived from the sum of CI values of each entry divided by the number of replications. Based on scale by [11] for selecting wheat varieties to powdery mildew, little modifica� tions were made and a rating scale for disease resistance as adapted by PARC Islamabad, Pakistan for measuring cereal rusts severity [12], and later adopted by ARC (Agricultural Research Council) of Great Britain for the farmers was fol� lowed in this study. Using the following formula, Area under disease progress curve (AUDPC) was calculated for individual plants from the calculat� ed C.I. values of the original rust severity data where Xi and X i + 1 are severity on date i and date i + 1, respectively and ti is the number of days bet� ween date i and date i + 1. Genotypes/accessions selected for genetic studies. After performing cluster analysis, for AUDPC, seven bread wheat genotypes with wide range of genetic variability Viz. Bakhtawar�92, Frontana, Saleem�2000, Tatara, Inqilab�91, Fakhre�Sarhad, and Karwan were used as parent material for hybridization. The accession Inqilab�91 was former� ly described to have resistance to stripe rust based on Yr9 and Yr27 [13]. Pedigrees and Salient fea� tures of the parent varieties are detailed as under. In the present paper, only four genotypes Viz. Bakhtawar�92, Frontana, Inqilab�91and Fakhre� Sarhad were used in two crosses. Crosses between other genotypes are to be left for further papers to avoid complication. Evaluation of six populations against stripe rust. After making successful crosses between the select� ed genotypes Viz. Bakhtawar�92 � Frontana and Inqilab � Fakhre�Sarhad, six multi�generations (P1, F1, P2, B1, B2, F2) of each cross were planted in the experimental field of Nuclear Institute for Food and Agriculture (NIFA), Peshawar, Pakistan during rabi 2006–2007 in three replications with Randomized Complete Block Design (RCBD). The row length of 5 meters was kept for each pop� ISSN 0564–3783. Цитология и генетика. 2009. № 426 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak ulation but number of rows were varied i.e. two rows for parents and F1, four rows for BC1 and BC2 and 8 rows for F2 populations of all the two cross� es in each replication. The plant to plant and row to row spacing was maintained 10 and 30 cm respectively. Seeds were sown at 2.5 cm depth at the rate of 2 seed per hil which were later on thinned to single healthy seedling per hil after ger� mination. Same methodology was used for creat� ing artificial epiphytotic conditions, recording dis� ease severity and working out AUDPC as men� tioned for the germplasm. Starting from March 24, 2007 when the wheat plants were at growth stages from booting to milk [14], rust severity was record� ed at four intervals (24th March, 31st March, 7th April and 14th April 2007 with in elapse of one week interval between to consecutive readings) on the same randomly selected plants (60 plants from each of the parental, 90 from F1s, 150 plant from each of B1s and B2s while 210 plants from each of the F2s populations). Data collection was complet� ed with in 12 hours on each recording date. Statistical Analysis. Mean values regarding AUDPC and standard deviations for all the acces� sions were worked out by using MS excel pro� gramme. For performing cluster analysis with respect to classification of germplasm, Euclidean distance was estimated for all pairs of accessions. The resul� ting Euclidean dissimilarity coefficient matrices were used to established the relationship between the accessions using wardґs method (Statistica ver� sion 7.0) Joint Segregation Analysis (JSA). The data regarding AUDPC were analyzed according to five ІSSN 0564–3783. Цитология и генетика. 2009. № 4 27 Assessment of genes controlling Area Under Disease Progreess Curve (AUDPC) for stripe rust Table 1 Assessment and evaluating of stripe rust reaction and measurement of coefficient of infection O – No visible infection R – Resistant. Necrotic areas with or without minute uredia MR – Moderately resistant. Small uredia present surrounded by necrotic areas MS – Moderately susceptible. Medium uredia with no necrosis but possibly some distinct chlorosis S – Susceptible Large uredia and little or no chlorosis present TR – Trace severity of resistant type infection 10MR – 10 percent severity of a moderately resistant type infection 50S – 50 percent severity of a susceptible type infection Reaction No disease Resistant Resistant to Moderately Resistant Moderately Resistant Moderately Resistant to Moderately Susceptible Moderately Susceptible Moderately Susceptible to Susceptible Susceptible Observation O R R�MR MR MR�MS MS MS�S S Response value 0.0 0.2 0.3 0.4 0.6 0.8 0.9 1.0 Table 2 The response of individual plants within each population to the type of stripe rust infection Genotype Bakhtawar�92 Frontana Saleem�2000 Tatara Inqilab�91 Fakhre�Sarhad Karwan KAUZ 'S' Fronteira/Mentana CHAM�6//KITE/PGO JUP/ALD "S"//RLT 'S'/3VEE'S') WL 711/CROW 'S' PFAU 'S'/SERI/BOW 'S' C182.2/C166.3/3/CNO/7C2*//CC//TOB/SWM6828 Pakistan (CIMMYT based) Brazil Pakistan (CIMMYT based) NIFA, Peshawar Pakistan (CIMMYT based) Pakistan (CIMMYT based) Pakistan (CIMMYT based) 143.40 35.10 103.20 45.67 244.80 60.29 70.50 Pedigree Origin/Source AUDPC different groups of genetic models as outlined by Gai [15, 16]. 1. One major�gene inheritance (A�1, A�2, A�3 and A�4). 2. Two major�gene inheritance (B�1, B�2, B�3, B�4, B�5 and B�6). 3. Polygene and polygene inheritance (D, D�1, D�2, D�3 and D�4). 5. Two Major gene and polygene inheritance (E, E�1, E�2, E�3, E�4, E�5 and E�6). The observations were recorded on individual plants from each of the six populations i.e. the two homozygous parents (P1 and P2), the first filial generation (F1), the two backcrosses (B1 and B2)), and the second filial generation (F2). Based on the assumptions [13, 14], the data was subjected to 24 types of genetic models of five groups. The most suitable genetic models in each cross were chosen by using maximum log of likely hood values [13, 17, 18] and Akaikeґs information criterion (AIC). Further selection of the best fit genetic model was made on the basis of least number of significant values of χ2 statistics, Smirnov statistics and Kol� mogorov statistics [14]. The data were analyzed by using statistical software Sin. Exe, the major gene� polygene mixed inheritance model to a joint analy� sis of multi�generations [16] specially designed for six generations i.e. P1, P2, F1, BC1, BC2, and F2. In case of the best fit model the values of second order genetic parameters as well as and for B1, B2 and F2 were worked out by using excel program of win� dows. Results. Genetic diversity for stripe rust and selec� tion of genotypes for crosses. Based on Area Under Disease Progress Curve (AUDPC), Euclidean dis� similarity coefficient matrix (not shown) was con� structed for 45 wheat accessions and phenogram ISSN 0564–3783. Цитология и генетика. 2009 № 428 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak Table 3 Grouping based on different clusters for 45 Bread wheat accessions evaluated during 2003 Cluster 1 2 3 Mean/SD Accessions with Euclidean Distances Frequ� ency 9 11 13 20 24.44 28.88 104.49 ± 14.31 133.88 ± 13.66 73.57 ± 18.84 % age Group A Group B Saleem� 2K (6.63) CB�171 (4.83) B�92 (7.51) DRRM 03 (7.14) Frontana (13.68) CT� 02204 (3.38) CT� 02248 (4.34) CT� 02306 (5.89) CM�03� 04 (5.44) Tatara (7.34) CT� 02390 (5.54) CT� 01183 (6.65) CT� 01084 (4.19) V�2156 (6.65) F�Sarhad (7.76) Karwan (2.81) CB�61 (8.43) Metal Tail (5.90) CT� 02009 (5.54) CT� 99022 (4.98) CB�185 (8.62 CB�82 (6.21) CT� 02019 (6.48) V�03007 (8.46) AS�2002 (7.84) CB�148 (4.64) CT� 02081 (6.48) CB�145 (10.61) CB�195 (9.77) CT� 02266 (2.44) BANA�4 (16.16) UQAB (6.40) CT� 02267 (3.45) 4 5 9 3 20 6.67 178.65 ± 12.94 244.40 ± 6.61 CT�02192 (5.18) E�29 (5.91) Inqilab�91 (6.46) V�84051 (7.10) CB�197 (9.79) Soleman (4.37) CB�289 (5.80) CB�179 (6.92) CB�196 (6.50) CB�325 (4.44) E�41 (4.24) Mango (6.28) Note. In Parentheses is the Euclidian distance representing the repartition/closeness among the lines including in the same cluster. ІSSN 0564–3783. Цитология и генетика. 2009. № 4 29 Assessment of genes controlling Area Under Disease Progreess Curve (AUDPC) for stripe rust T a b le 4 Fr eq ue nc y di st ri bu ti on o f p la nt s po pu la ti on u nd er A U D P C le ve l i n P 1, F 1, B C 1, B C 2 an d F 2 ge ne ra ti on o f t w o br ea d w he at ( Tr it ic um ae st iv um L .) c ro ss es G e n e ra � ti o n P 1 F 1 P 2 B C 1 B C 2 F 2 3 2 5 � 0 � 8 1 1 7 8 2 0 2 7 2 0 1 7 2 0 2 9 2 0 2 5 1 1 5 2 4 2 0 2 1 1 2 9 1 8 2 1 1 4 2 5 1 4 1 9 5 2 4 9 1 8 3 2 1 8 2 2 2 0 1 9 6 2 1 1 9 1 3 4 2 0 1 4 7 1 5 4 7 7 6 0 9 0 6 0 1 5 0 1 5 0 2 1 0 2 3 3 .2 8 1 5 5 .0 0 6 5 .9 8 3 6 9 9 .5 0 2 5 0 4 .1 0 5 7 6 9 .5 0 5 4 5 .1 6 ± 2 3 .3 5 1 4 4 .9 1 ± 1 2 .0 4 5 6 5 .7 2 ± 6 5 .9 8 3 6 9 9 .5 0 ± 6 0 .8 2 2 5 0 4 .0 8 ± 5 0 .0 4 5 7 6 9 .5 3 ± 7 5 .9 6 P 1 F 1 P 2 B C 1 B C 2 F 2 5 1 0 6 2 2 5 8 1 2 2 2 8 1 2 1 5 7 2 3 2 1 2 0 6 4 1 5 2 3 1 8 1 2 1 5 2 4 1 9 4 9 1 4 2 3 1 9 2 3 1 5 1 8 1 8 2 1 5 1 1 1 9 5 1 2 2 1 1 7 1 2 2 1 2 1 7 1 4 1 5 9 8 6 0 9 0 6 0 1 5 0 1 5 0 2 1 0 2 3 3 .2 8 1 5 5 .0 0 6 5 .9 8 3 6 9 9 .5 0 2 5 0 4 .1 0 5 7 6 9 .5 0 5 4 5 .1 6 ± 2 3 .3 5 1 4 4 .9 1 ± 1 2 .0 4 5 6 5 .7 2 ± 6 5 .9 8 3 6 9 9 .5 0 ± 6 0 .8 2 2 5 0 4 .0 8 ± 5 0 .0 4 5 7 6 9 .5 3 ± 7 5 .9 6 2 5 � 5 0 � 7 5 � 1 0 0 � 1 5 0 � 1 2 5 � 1 7 5 � 2 0 0 � 2 2 5 � 2 5 0 � 2 7 5 � 3 0 0 � S a m p le S iz e M e a n P h e n o ty p ic V a ri a n c e /S D R a n g e o f A re a U n d e r D is e a se P ro g re ss C u rv e ( A U D P C ) C ro ss 1 ( B a k h ta w a r� 9 2 � F ro n ta n a ) C ro ss 2 ( In q il a b �9 1 � F a k h re �S a rh a d ) constructed is presented in Fig. 1. The dissimilarity range was from 2.44 to 16.16 among all the acces� sions. The dendrogram showed two groups and five clusters. Group A consisted on three clusters and B on two ones. Since the cluster analysis is based on AUDPC therefore, the clusters were obtained on the basis of linkage distance and related traits. Grouping based on different clusters along with Euclidean distances, means and standard devia� tion is presented in Table 3. In group A, nine geno� types i.e. Saleem�2k, CT�02248, CT�01183, CB� 61, CB�185, AS�2002, CB�145 and BANA�4 were in cluster 1 which presents 20 percent of the total material (Table 4). The accessions in cluster 1 (9 % of the total material) showed AUDPC in acceptable range (104.49 ± 14.31) < (182). Cluster 2 (Table 3) accounts for 24.44 percent of the total material and consists of eleven accessions (Bakhtawar�92, CT� 02306, CT�01084, Metal Tail, CB�82, CB�148, DRRM�03–04, CM�03–04, V�2156). Cluster 3 is consisted of 28.88 % of the total population and comprised of thirteen accessions (Frontana, Tatara, Fakhre�Sarhad, CT�02009, CT�02019, CT�02081, CT�02266, CT�02267, CT�02204, CT�02390, Karwan, CT�99022 and V� 03007). Having very low AUDPC (73.57 ± 18.8), the accessions included in this cluster showed high level of resistance to the disease and can be utilized as source of resistance for stripe rust. Clusters 4 and 5 representing 20 and 7 % of the total materi� ISSN 0564–3783. Цитология и генетика. 2009. № 430 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak Fig. 1. Phonogram based on eleven quantitative traits in 45 wheat genotypes used as germplasm ІSSN 0564–3783. Цитология и генетика. 2009. № 4 31 Assessment of genes controlling Area Under Disease Progreess Curve (AUDPC) for stripe rust Fig. 2. Frequency distribution of plant population: a – under AUDPC level of F2, P1 and P2 in cross 1; b – under AUDPC level in F2, BC1 and BC2 for cross 1; c – under AUDPC level in F1, P1 and P2 for cross 3; d – under AUDPC F2, BC1, and BC2 for cross 3 al and with AUDPC of 178.65 and 244.0 respec� tively were lying in susceptible and highly suscepti� ble range. On the basis of susceptibility and high level of resistance to stripe rust, the crosses were performed between highly susceptible and highly resistant parents so as to determine the gene action on the control of the disease. Genetic control of stripe rust resistance (AUDPC). The frequency distribution and the mean values (Table 3), show the tendency of F1 and BC2 towards the resistant parents (Frontana, and Fakhre� Sarhad) which were used as the pollen donor par� ents in the crosses. Normal distribution of F2 and occurrence of transgressive segregants of resistant as well as susceptible types indicate the quantita� tively controlled nature of AUDPC. Transgressive segregation for resistant plants refers to the pres� ence of resistant genes in the parents for control� ling stripe rust. The susceptible transgressive segre� gants refer to the fact that some negative genes were also dispersed in the parents which affected the resistance when came in accumulation in indi� vidual of F2 or those of subsequent generations. The frequency distribution represented as linear bar chart for six generations (Fig. 2) clarify the behaviour and tendency of each generation in the crosses. Highest phenotypic variances ranged between 2504.08 and 6658.02 for the segregating progenies (Table 4) indicate that the trait was high� ly influenced by the environmental conditions. Genes pattern and selection of suitable genetic models for controlling AUDPC. Using the criterion of the maximum log of likelihood estimates and smaller AIC values (Table 5), Model E, E�1 and B� 1 were most suitable for controlling AUDPC in ISSN 0564–3783. Цитология и генетика. 2009. № 432 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak Fig. 2. Finish Table 5 Maximum likelihood estimates and AIC values for AUDPC under various genetic models estimated through the IECM* algorithm Model A�1 A�2 A�3 A�4 B�1 B�2 B�3 B�4 B�5 B�6 C C�1 D D�1 D�2 D�3 D�4 E E�1 E�2 E�3 E�4 E�5 E�6 Maximum log of likeli� hood –3862.55 –3874.50 –3992.06 –3922.90 –3727.13 –3807.06 –3858.87 –3911.65 –3991.57 –3991.57 –3771.80 –3813.54 –3737.84 –3759.35 –3759.35 –3807.42 –3785.38 –3701.76 –3722.78 –3765.82 –3729.67 –3781.47 –3800.74 –3771.56 AIC 7733.10 7755.00 7990.12 7851.80 7474.26 7626.12 7725.74 7829.32 7991.15 7989.15 7563.60 7641.08 7499.68 7536.71 7534.71 7630.84 7586.77 7439.53 7475.57 7553.64 7477.34 7578.94 7619.48 7559.12 Model A�1 A�2 A�3 A�4 B�1 B�2 B�3 B�4 B�5 B�6 C C�1 D D�1 D�2 D�3 D�4 E E�1 E�2 E�3 E�4 E�5 E�6 Maximum log of like� lihood –3900.42 –3913.78 –4086.09 –4038.12 –3769.34 –3852.96 –3945.91 –3929.03 –4074.69 –4074.69 –3788.73 –3828.23 –3768.41 –3778.32 –3778.32 –3813.94 –3793.32 –3756.51 –3760.58 –3790.63 –3778.03 –3796.56 –3816.85 –3781.50 AIC 7808.83 7833.56 8178.18 8082.24 7558.69 7717.92 7899.82 7864.05 8157.38 8155.38 7597.46 7670.46 7560.83 7574.65 7572.65 7643.88 7602.65 7549.02 7551.16 7603.26 7574.06 7609.13 7651.71 7579.00 Cross 1: Bakhtawar�92 � Frontana Cross 2: Inqilab�91 � Fakhre�Sarhad *IECM: Iterated Expectation and Conditional Maximiza� tion (Gai and Wang, 1998) cross 1 while models E�1, D�2 and B�1 were suitable for cross�2. Further selection of the best fit model for each cross was made on the basis of least num� ber of significant values of the five statistics pre� sented in Table 6, clearly showing that E and E�1 were the best fit models for cross 1 and cross 2 respectively. Using the component parameters given in Table 7 the first and second order genetic param� eters for corresponding best fit genetic model for the two crosses were calcu lated (Table 8). ІSSN 0564–3783. Цитология и генетика. 2009. № 4 33 Assessment of genes controlling Area Under Disease Progreess Curve (AUDPC) for stripe rust Table 6 Tests for goodness�of�fit regarding AUDPC of model B�1, E and E�1 for crosses Bakhtawar�92 � Frontana and Inqilab�91 � Fakhre�Sarhad Cross 2: Inqilab�91 � Fakhre�Sarhad Model E B�1 E�1 E E�1 B�1 P1 F1 P2 B1 B2 F2 P1 F1 P2 B1 B2 F2 P1 F1 P2 B1 B2 F2 P1 F1 P2 B1 B2 F2 P1 F1 P2 B1 B2 F2 P1 F1 P2 B1 B2 F2 0.08(0.77) 0.01 (0.92) 0.67 (0.41) 0.82(0.36) 0.02(0.89) 0.60 (0.43) 0.51 (0.47) 12.59 *** 0.17(0.68) 0.00 (0.95) 0.01(0.92) 35.21 *** 0.07 (0.79) 0.00(0.94) 0.84(0.36) 0.75 (0.38) 0.67 (0.41) 6.86** 0.00(0.99) 0.00 (1.0) 0.00 (1.0) 2.75 * 0.01(0.93) 1.22(0.27) 0.12(0.73) 0.00(0.98) 0.12(0.73) 3.57(0.59) 3.02(0.08) 1.20(0.27) 0.12(0.73) 0.12(0.73) 0.14(0.70) 6.77 ** 0.40(0.52) 2.25(0.13) 0.33 (0.57) 1.42 (0.23) 2.52 (0.11) 0.06(0.80) 0.15(0.70) 0.69(0.40) 1.58 (0.21) 19.51 *** 0.82 (0.36) 0.03 (0.86) 0.00 (0.96) 46.81 *** 0.28 (0.59) 1.18(0.28) 2.66 (0.10) 0.80 (0.37) 0.59 (0.44) 8.11*** 0.57(0.45) 0.54(0.46) 0.79 (0.37) 2.16(0.14) 0.00(0.98) 2.07(0.15) 0.18(0.67) 0.52 (0.43) 1.49(0.22) 3.63(0.06) 2.83(0. 09) 2.77(0.09) 0.03(0.84) 0.85(0.35) 0.00(0.94) 6.15 ** 1.75(0.19) 4.23* 11.59 *** 19.00 *** 10.08 *** 6.37 ** 0.96(0.32) 0.11(0.73) 5.10 ** 15.42 *** 4.12 ** 0.24 (0.62) 0.03 (0.86) 19.23 (0.15) 9.77*** 21.15 *** 8.87 *** 0.06(0.81) 0.10(0.90) 1.56 (0.21) 9.15*** 8.65 *** 12.62*** 0.30(0.58) 0.20(0.65) 2.16(0.14) 9.11*** 8.71 *** 12.57 *** 0.09(0.76) 0.00(0.99) 5.83** 0.38 (0.54 25.52*** 1.28(0.26) 0.03 (0.87) 8.00*** 5.82** 0.28 (>0.05) 0.43 (>0.05) 0.10 (>0.05) 0.25(>0.05) 0.05 * 0.11 (>0.05) 0.18* 1.85 (>0.05) 0.22 (>0.05) 0.04 ** 0.04*** 3.77 (>0.05) 0.24 (>0.05) 0.49 (>0.05) 0.39 (>0.05) 0.19 (>0.05) 0.09 ** 0.69 (>0.05) 0.23 (>0.05) 0.19 (>0.05) 0.24 (>0.05) 0.34 (>0.05) 0.03 ** 0.23 (>0.05) 0.24 (>0.05) 0.19 (>0.05) 0.31 (>0.05) 0.38 (>0.05) 0.28 (>0.05) 0.28 (>0.05) 0.07 * 0.60 (>0.05) 0.09 ** 0.77 (>0.05) 0.33 (>0.05) 0.36 (>0.05) 0.13 * 0.13 * 0.13 * 0.07 * 0.05* 0.05 * 0.11 * 0.23 (>0.05) 0.12** 0.04 ** 0.05*** 0.21 (>0.05) 0.11** 0.14* 0.13** 0.08 ** 0.06* 0.09** 0.09** 0.11*** 0.11 *** 0.08** 0.04** 0.07** 0.11** 0.11** 0.12** 0.09** 0.07* 0.07* 0.07** 0.17(>0.05) 0.07** 0.12(>0.05) 0.10*** 0.09** Generation U1 2 U2 2 U2 3 nW2 Dn Cross 1: Bakhtawar 92 � Frontana Note. In parenthesis is the probability value. *, **, *** represents the 0.05, 0.01, 0.001 significance levels respectively U1 2 , U2 2 , U2 3 : χ2 statistics with 1 degree of freedom; nW 2 : Smirnov’s statistics; Dn : Kolmogorov’s statistics. Genetic model E for cross 1 determines mixed additive�dominant�epistatic effect of major genes plus additive – dominant�epistasis of polygenes. The additive (da, db) and dominant (ha, hb) effects contributed by two major genes (A & B) to the control of AUDPC were estimated to be 83.65, 24.83 and –25.19, –6.37 respectively. The positive signs of the additive effect with respect to major genes in the cross indicated that AUDPC was con� trolled by the positive additive action of the major genes where as the negative signs of the dominant components of the major genes indicate that resistance to stripe rust was adversely affected by the dominant action of the major genes. The dom� inant ratios (ha/da and hb/db) of the gene A and B was –0.30 and –0.26 respectively, representing the predominance of the additive gene action due to major genes rather then the dominant effect. The negative signs of non allelic dominant interaction of the two major genes as well as of additive � addi� tive effect (i) in the cross indicate the dispersion of some negative genes in parents (Bakhtawar�92 and Frontana), which adversely affected resistance to stripe rust. Therefore, selection for resistance should be delayed to subsequent generations till maximum resistant polygenes are accumulated in the individual plants. The additive � dominant effect of gene A over gene B (Jab) and that of B over A (Jba) was 14.67 and 24.08 respectively. The dom� inant � dominant type of non allelic interaction (l) was recorded as 10. Genetic control of AUDPC in cross 2. Model E� 1(best fit for cross 2), representing mixed action of two major additive�dominance epistatic genes plus additive�dominant polygenes. The population mean (242.98) (Table 8) refers to the average AUDPC equal to the mean of F2 generation. The negative signs of the dominant effect (–74.29& –100.56) due to first and second major genes (A & B) in these crosses represent that resistance to stripe rust is controlled by negative dominant effect of the major genes. Additive effect due to the two major genes (A & B) was conspicuous in controlling AUDPC in cross Inqilab�91 � Fakhre Sarhad with higher effect due to gene A (28.32) then that of gene B (4.34). The negative sign under mixed additive � additive (i) type of genetic effect repre� sents the dispersion of some negative polygenes between the parents (Inqilab and Fakhre Sarhad) which adversely affect the AUDPC when come in combination in the segregating progenies. However, the over all additive effect due to polygene was higher and positive (91.29) representing the conspic� uous favourable effect of polygene on AUDPC. The dominant � dominant (l) type effect was the highest (101.63) representing the favurability of ISSN 0564–3783. Цитология и генетика. 2009. № 434 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak Table 7 Maximum likelihood estimates of component parameters regarding AUDPC for four Bread wheat crosses in their respective best fit models Cross 2: Inqilab 91 � Fakhre�Sarahad (Model E�1) Parameter μ1 μ2 μ3 μ41 μ42 μ43 μ1 μ2 μ3 μ41 μ42 μ43 233.28 155.00 65.98 249.10 233.42 175.38 309.53 185.32 78.23 287.82 124.80 124.54 μ44 μ51 μ52 μ53 μ54 μ61 μ44 μ51 μ52 μ53 μ54 μ61 130.23 154.00 101.33 60.55 55.91 256.63 207.04 148.04 228.41 175.61 115.52 258.32 μ62 μ63 μ64 μ65 μ66 μ67 μ62 μ63 μ64 μ65 μ66 μ67 240.96 208.67 182.91 137.76 85.10 91.03 95.29 299.87 95.04 177.54 257.91 299.87 μ68 μ69 σ2 σ4 2 σ5 2 σ6 2 μ68 μ69 σ2 σ4 2 σ5 2 σ6 2 44.31 39.67 355.65 931.67 759.40 355.65 205.12 145.02 276.12 1083.18 1560.68 963.41 Estimate Parameter Estimate Parameter Estimate Parameter Estimate Cross 1: Bakhtawar 92 � Frontana (Model E) mixed epistasis due to major genes and polygenes in controlling AUDPC in Inqilab�91 � Fakhre� Sarhad. Dominance due to polygenes though small� er (15.57) but was favourable because of its positive sign value for controlling the trait (Table 8). Under the second order genetic parameters (Table 7), the phenotypic variation (σp2) is parti� tioned into genetic and environmental variation (σe2) for the two crosses. The genetic component of vari� ation in turn is subdivided into variation due to major genes (σmg2) and polygenes (σpg2). Since resist� ance to stripe rust is controlled by two major genes plus polygenes therefore, the phenotypic variance (σp2) in BC1, BC2 and F2 was higher in both the crosses. The major�gene heritability (hmg2) which is the most important second order parameter was 73.49, 48.99 and 87.12 in BC1, BC2 and F2 respec� tively for cross 1. The polygene heritability (hpg2) which is less important component was estimated as 16.90, 36.80 and 6.71 for BC1, BC2 and F2 respec� tively in cross Bakhtawar�92 � Frontana. For cross 2, the major gene heritability was 72.76, 63.06 and 86.25 where as the polygene heritability was 22.51, 28.14 and 9.61 for BC1, BC2 and F2 respectively. Discussion and conclusions. Using AUDPC as the measure of stripe rust resistance in wheat, the data analysis of the present paper was made under the procedures outlined by [15, 19] with the advantage over the method suggested by [20] as the former has the power to determine the number of major genes, individual effects due to the major genes as well as collective effect of the polygenes involved in the controlling of the trait. Moreover, the data is subjected to twenty�four different genetic models as suggested by [16]. According to the procedure, individual effects of the major genes were also determined under the second order genetic parameters (Table 8). In contrast the later procedure measures the trait only as the poly� genic system without measuring the effect of indi� vidual genes [19]. The crosses were between resistant and suscep� tible parents using the resistant one as the pollen donor parent in F1. Frequency distribution of plant population for AUDPC revealed transgressive seg� regation with respect to susceptibility and resist� ance in the segregating generations (F2) of all the crosses. Susceptible transgressive segregants have ІSSN 0564–3783. Цитология и генетика. 2009. № 4 35 Assessment of genes controlling Area Under Disease Progreess Curve (AUDPC) for stripe rust Table 8 Estimates of first and second order genetic parameters for Stripe rust resistance (AUDPC) in four bread wheat crosses Cross 2: Inqilab�91 � Fakhre�Sarhad (Model E�1) 1 st order parameter m1 m2 m3 m4 m5 m6 da db m da db ha hb ha/da hb/db 242.98 28.32 4.34 –74.29 –100.56 –2.62 –23.17 i jab jba l [d] [h] –49.10 –83.24 –109.76 101.63 91.29 15.57 σp 2 σmg 2 σe 2 σpg 2 hmg 2 (%) hpg 2 (%) 5833.14 4244.2 276.12 1312.80 72.76 22.51 3138.64 1979.20 276.12 883.32 63.06 28.14 6658.02 5742.29 276.12 639.62 86.25 9.61 125.65 166.24 175.31 141.47 165.24 145.98 83.65 24.83 ha hb ha/da hb/db i jab jba l –25.19 –6.37 –0.30 –0.26 –0.85 14.67 24.08 10.12 3699.50 2718.6 355.65 625.26 73.49 16.90 2504.1 1226.82 355.65 921.63 48.99 36.80 5769.5 5026.59 355.65 387.29 87.12 6.71 σp 2 σmg 2 σe 2 σpg 2 hmg 2 (%) hpg 2 (%) Estimate 1 st order parameter Estimate 2 nd order parameter BC1 BC2 F2 Estimate Cross 1: Bakhtawar�92 � Frontana (Model E) also been reported by Bjarko and Line [21] for leaf rust and Ma et al. [22] for stripe rust in wheat. Transgressive segregants in half diallel wheat crosses have also been mentioned in case of Septoria tritici blotch resistant [23]. Both susceptible and resistant type of transgressive segregants for stripe rust were reported by [8] in F2 and F3 generations of some wheat crosses. The fitness of the two different models (model E for cross1 and model E�1 for cross 2) in the two crosses is because of the difference in the genetic background of the parents involved in the two crosses. However, AUDPC in both the crosses was under the control of two major genes plus poly� genes. The ratios of dominance to additive effect (h/d) for both the major genes in the two crosses have negative sign valves, referring to the recessive� ly controlled nature of AUDPC in both the cross� es. The positive sign and higher values of the addi� tive effects due to the major genes show pre domi� nance of the additive effect on AUDPC in both the crosses. The estimated additive effects due to major gene A and B in the crosses were ranging from 28.32 to 83.65 and 4.34 to 24.83 respectively (Table 8). The negative and positive signs of the additive as well as dominant effect due to the major genes and polygenes in different crosses may occur due to the difference in the genetic background of the parents involved in the crosses [19]. Generally, the dominant and additive effects exerted by poly� genes were less than those of the major genes. It is because the polygenes contributed very low frac� tion to the phenotypic variation (σp2) with very low values of polygene heritability (16.90, 36.80, 6.71 % in cross 1 and 22.51, 28.14, 9.61 % in cross 2 for BC1, BC2 and F2 respectively). The present results are in accordance to those found by [19] regarding resistance to bean fly in soybean with respect to heritability values due to major genes as well as polygenes. Under the mix epistasis effect of both major as well as polygenes for cross 1, nega� tive genes for controlling AUDPC were present among the two parents which means that selection for resistance should be delayed to subsequent gen� erations till maximum resistant polygenes are accumulated in more or less homozygous form in the individual plants. Additive effect with respect to stripe rust resistance has also been reported by some recent investigators in some wheat crosses [17]. The additive � dominant effect (J) due to the second major gene and dominant � dominant effect (l) under epistasis was positive for cross 1. Additive � dominant as well as dominant � domi� nant epistasis for leaf rust in some wheat crosses has also been reported by [21] which coincides with the present results in case of cross 1. An addi� tive/modifying action of two genes for stripe rust in a segregating generation resulted from a cross between susceptible and resistant cultivars of wheat have also been suggested [4]. In another study [8], segregation ratio of 1: 2: 5, has been reported suggesting the involvement of three genes with epistasis for resistance to stripe rust at seedling stage. In a cross between highly resistant and susceptible parents, two genes were suggested with additive effect to be responsible for stripe rust resistance in wheat [22]. Based on a joint scaling test, while conducting studies on gene action regarding durable, high� temperature, adult�plant (HTAP) resistance for stripe rust in parental, F1, F2 and backcross popu� lations for some crosses in wheat, [24] reported the involvement of epistasis in controlling AUDPC with significant additive � additive component. Using generation mean analysis, [25] has reported additive�dominance model (absence of epistasis) digenic epistasis with predominant additive gene effect, significant «i» type and «l» type of epistatic interaction for powdery mildew in different cross� es of wheat. The previous results are more or less in correspondence with the two crosses of the present study. However, the contradictions between the pres� ent and the previous results might because all these previous investigators used either diallel or genera� tion mean analysis as the statistical approach which measure the genetic effect as the polygenic system and have no power to determine the effect of the individual major genes and aggregate effect of the polygene. The first author acknowledges the award of schol� arship by Higher Education Commission of Pakistan (HEC) as a visiting Scientist to Institute of Biotech� nology, Jiangsu Academy of Agricultural Science, Nanjing, China. The statistical procedures adapted in the present study were suggested by Prof. Dr. Hongxiang Ma, Head, Institute of Biotechnology, Jiangsu Academy of Agricultural Science, Nanjing, China for which the author acknowledges his efforts. ISSN 0564–3783. Цитология и генетика. 2009. № 436 M. Irfaq, Mir Ajab, Ma Hongxiang, GSS Khattak M. Irfag, Mir Ajab, Ma Hongxiang, GSS Khattak ASSESSMENT OF GENES CONTROLLING AREA UNDER DISEASE PROGREESS CURVE (AUDPC) FOR STRIPE RUST Генетические эффекты контроля устойчивости к желтой ржавчине злаков были определены в двух скрещиваниях пшеницы Bakhtawar�92 � Frontana (скрещивание 1) и Inquilab�91 � Fakhre�Sarhad (скре� щивание 2) с использованием Area Under Disease Progress Curve (AUDPC) для измерения устойчивости. Устойчивые и чувствительные генотипы в этих скре� щиваниях были определены с помощью начальной оценки на устойчивость к желтой ржавчине 45 образ� цов пшеницы. Модель смешанного наследования бы� ла применена к анализу данных шести основных по� пуляций P1, F1, P2, B1, B2 и F2 в скрещиваниях. Резуль� таты показали, что AUDPC в скрещивании 1 контро� лируется двумя основными генами с аддитивно�до� минантным эпистатическим эффектом и полигенами с аддитивно�доминантными эпистатическими эф� фектами (модель Е). В случае скрещивания 2 – под контролем двух основных генов с аддитивно�доми� нантным эпистатическим эффектом плюс аддитивно� доминантных полигенов (модель Е�1). Аддитивный эффект был преобладающим над всеми остальными типами генетических эффектов, что позволяет пред� положить задержку селекции на устойчивость до тех пор, пока максимальное количество позитивных ге� нов накапливается у особей последующих поколений. Наличие трансгрессивных сегрегантов на чувстви� тельность и устойчивость показало наличие как генов устойчивости, так и неких негативных генов у родите� лей. Наследуемость основного гена было выше, чем наследуемость полигенов для B1, B2 и F2 в скрещива� ниях. Наследуемость основного гена так же, как и по� лигенов, была в пределах от 48,99 до 87,12 % и от 2,26 до 36,80 % для двух скрещиваний соответствен� но. Наибольшая фенотипическая вариабельность в AUDPC (от 2504.10 до 5833,14) в сегрегирующих по� колениях (ВС1, ВС2 и F2) показывает, что на проявле� ние признака влияют факторы окружающей среды. M. Irfag, Mir Ajab, Mа Hongxiang, GSS Khattak ASSESSMENT OF GENES CONTROLLING AREA UNDER DISEASE PROGREESS CURVE (AUDPC) FOR STRIPE RUST Генетичні ефекти контролю стійкості до жовтої ір� жі злаків були визначені в двох схрещуваннях пшени� ці Bakhtawar�92 � Frontana (схрещування 1) и Inquilab� 91 � Fakhre�Sarhad (схрещування 2) з використанням Area Under Disease Progress Curve (AUDPC) для вимі� рювання стійкості. Стійкі та чутливі генотипи в цих схрещуваннях були визначені за допомогою початко� вої оцінки на стійкість до жовтої іржі 45 зразків пше� ниці. Модель змішуваного спадкування була застосо� вана до аналізу даних шести основних популяцій P1, F1, P2, B1, B2 та F2 в схрещуваннях. Результати показа� ли, що AUDPC у схрещуванні 1 контролюється двома основними генами з адитивно�домінантним епіста� тичним ефектом і полігенами з аддитивно�домінант� ними епістатичним ефектами (модель Е). У випадку схрещування 2 – під контролем двох основних генів з адитивно�домінантним епістатичним ефектом плюс адитивно�домінантних полігенів (модель Е�1). Ади� тивний ефект був переважаючим над всіма іншими типами генетичних ефектів, що дозволяє припустити затримку селекції на стійкість до того часу, поки мак� симальна кількість позитивних генів накопичується у особин наступних поколінь. Наявність трансгресив� них сегрегантів на чутливість та стійкість показала на� явність як генів стійкості, так і деяких негативних ге� нів у батьків. Успадковування основного гена було ви� ще, ніж успадкування полігенів B1, B2 та F2 в схрещу� ваннях. Успадковування основного гена, також як і полігенів була в межах від 48,99 до 87,12 % та від 2,26 до 36,80 % для двох схрещувань, відповідно. Най� більша фенотипічна варіабельність в AUDPC (від 2504.10 до 5833.14) в сегрегуючих поколіннях (BС1, BС2 та F2) показує, що на виявлення ознаки вплива� ють фактори оточуючого середовища. REFERENCES 1. Jing Feng, Zhongjun Zhang, Guohui Li, Yu Zhou1, Haihong Wang, Qinggang Guo and Jian Sun. 2007. Inheritance of resistance to stripe rust in winter wheat cultivars Aquileja and Xian Nong 4. J Appl Genet. 48(1):43–46. 2. Imtiaz M., Cromey M.G., Hampton J.G., Ogbonnaya F.C. 2005. Genetics of stripe rust resistance in `Karamuґ wheat. Australian Journal of Agricultural research, Vol. 56:619–624. 3. 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