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Barakat M.N.,Plant Genetic Manipulation and Genomic Breeding Group | Al-Doss A.A.,Plant Genetic Manipulation and Genomic Breeding Group | Al-Doss A.A.,King Saud University | Elshafei A.A.,Plant Genetic Manipulation and Genomic Breeding Group | Moustafa K.A.,King Saud University
Australian Journal of Crop Science

The objective of this study was to estimate inheritance of the grain filling rate as indicator for heat tolerant genes. The minimum number of genes for the trait in bread wheat was also assessed by combining quantitative genetic estimates and SSR marker analyses. Two cultivars, Debra (heat-tolerant) and Yecora Rojo (heat-sensitive) crossed and F1 and F2 populations generated. The parents, F1 and 162 F2 plants were planted in winter season 2009 to evaluate heat tolerance during the grain-filling period. The sowing date in the present investigation represents the heat stress conditions in Saudi Arabia. The minimum number of genes or factors controlling heat tolerance was estimated (1.5) and the broad sense heritability was estimated as 47.7 %. The results revealed that three SSR markers; Xgwm132, Xgwm577 and Xgwm617 were linked to grain filling rate (GFR) by quantitative trait loci (QTL) analysis of the F2 population. The results showed that regression analysis for the relationship between the three markers (Xgwm132, Xgwm577 and Xgwm617) and the phenotypes of F2 plants were highly significant and the coefficients of determination (R2) were 0.07, 0.25 and 0.03, respectively. This indicates that these three markers were associated with the grain filling rate as indicator for heat tolerant genes. The adjusted R2 values suggested that the Xgwm132, Xgwm577 and Xgwm617 accounted for 7%, 25% and 3% of the total phenotypic variation of heat tolerance in the F2 population, respectively. The results demonstrated that SSR markers, combined with bulked segregant analysis, could be used to identify molecular markers linked to the grain filling rate as indicator for heat tolerance in wheat. Source

Al-Doss A.A.,Plant Genetic Manipulation and Genomic Breeding Group | Al-Doss A.A.,King Saud University | Saleh M.,King Saud University | Moustafa K.A.,King Saud University | And 2 more authors.
African Journal of Agricultural Research

The objectives of the present study are to determine the performance of six promising durum wheat genotypes for yield stability under heat stress conditions and to compare the application and utility of SRAP (Sequence-Related Amplified Polymorphism) and TRAP (Target Region Amplified Polymorphism) marker techniques, for analysis of genetic diversity among durum wheat genotypes under heat stress. Field experiments were conducted for four sowing dates, over two seasons, to expose genotypes to different levels of heat stress during the grain-filling period. Grain yield and yield attributes during the grain filling period were investigated. Results indicated that significant variations were observed among different durum wheat genotypes in respect of all yield attributes. The effect of sowing date on the relative grain yield of durum genotypes was of greater magnitude than the effect of year. On the other hand, under the fourth sowing date (20th January), where heat stress was imposed, line KSUDW104 was the best performing line (3.26 ton/ha) out yielding Benysowef (2.21 ton/ha) by 47.5% and Kronos (2.41ton/ha) by 35.3%. This line should be recognized as heat tolerant germplasm. The regression coefficients were significant for the six durum genotypes which indicated that they were highly responsive to the change in the average productivity of the growing season. SRAP and TRAP markers, were assayed to determine the genetic diversity of 6 durum wheat genotypes. In SRAP analysis, 45 out of 128 bands (35.16%) were polymorphic while in TRAP analysis, 22 out of 55 bands (40.0%) were polymorphic. The dendrogram based on SRAP markers differed from that based on TRAP markers. © 2010 Academic Journals. Source

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