Drought tolerance related traits in bread wheat and its association with AFLP marker

To identify markers associated with drought tolerance related traits under two different moisture conditions including rainfed (drought stress) and supplementary irrigation, an experiment was conducted in two consecutive years (2013-2015). Among the AFLP primers used in this study, eight EcoRI/MseI primer combinations produced a total of 119 polymorphic bands with an average of 14.88 bands per marker. The average polymorphic information content (PIC) for all markers was calculated 0.298. Based on PIC, Shannon's index (I), expected heterozygosity (He) and effective allele (EA), the combination of E-ACT/M-CTT was identified as the best primer combination in distinguish of the studied genotypes. The relationship between agro-physiological traits as dependent variables and molecular data as independent variables was investigated using stepwise multiple regression analysis method and 76 and 98 markers associated with traits were identified under rainfed and supplementary irrigation conditions, respectively. Under supplementary irrigation conditions, the highest coefficient of determination (R2) was allocated for E-ACT/M-CTC-11 marker with more than 60% explanation of variations in peduncle weight, peduncle length, spike dry weight and grain weight per spike and E-ACT/M-CTT-8 with explanation of 62% variation of 1000 grain weight. Under rainfed conditions, the markers E-ACT/M-CTT-8 with 70%, E-ACG/M-CTG-2 with 57% and E-ACG/M-CAA-2 with 51%, explained the highest variation of 1000 grain weight, relative water lose and relative water content, respectively. The markers E-ACT/M-CTC-11 and E-ACG/M-CAA-20 explained 32% and 41% of the grain yield variance under supplemental irrigation and rainfed conditions, respectively. In this study, the marker E-ACT/M-CTT-8 explained more than 60% of the variation in 1000 grain weight under both experimental conditions. The results of this study can be useful in providing basic information for indirect selection of wheat traits using associated markers under rainfed conditions.