Interactive Effects of Vernalization and Photoperiod Loci on Phenological Traits and Grain Yield and Differentiation of Iranian Wheat Landraces and Cultivars

Abstract

Phenological stages and allelic variation of vernalization and photoperiod response genes play an important role in wheat environmental adaptation and grain yield. In the present study, phenological stages of 260 Iranian wheat landraces and cultivars were studied during two cropping years. In addition, allelic variation of vernalization and photoperiod markers were also investigated to identify the genetic basis of different phenological stages. Ppd-D1 and then Ppd-B1 were highly variable in cultivars and landraces, while Ppd-A1 showed lower variation. Distribution patterns of allele frequency in Vrn-B1b, Ppd-D1b-D001, and Ppd-D1 markers were remarkably different in cultivars and landraces. About 98% and 96% of landraces showed photoperiod-sensitive allele of Ppd-D1b-D001 and Ppd-D1 markers, respectively, while most of cultivars had photoperiod-insensitive alleles. The frequency of Vrn-B1a was 82.2% in cultivars and 100% in landraces. However, Vrn-A1a-E4 was 43% and 79% in cultivar and landraces, respectively. We have found that Ppd-D1, Ppd-B1, and Vrn-A1 have a decisive effect on phenological stages and the combination of Ppd-B1a, Ppd-D1b, and Vrn-A1b is the most abundant allelic compound. The combination of aaa, bbb, and aab alleles for these three loci led to increased yield, thousand kernel weight (TKW), and grain filling period and shortening of phenological stages. Cluster analysis based on phenological stages and growing degree-days (GDD) of phenological stages clearly separated cultivars from landraces. This clustering pattern was consistent with marker data. The findings of this study provide a comprehensive insight into the basis of genetic control of the phenological stages of Iranian wheat landraces and cultivars. Therefore, this information can be used to select desirable genotypes in future breeding programs.