Allelic variation at the VERNALIZATION-A1, VRN-B1, VRN-B3, and PHOTOPERIOD-A1 genes in cultivars of Triticum durum Desf.

Abstract

The durum wheat varieties from Ukraine, Russia, and Kazakhstan are characterized by the specific allelic composition of the VRN genes that sharply distinguish them from the Triticum durum varieties from other countries. For numerous varieties, the VRN alleles which previously were not found in tetraploid wheat were identified. The ability of wheat to adapt to a wide range of environmental conditions is mostly determined by the allelic diversity within genes regulating the vernalization requirement (VRN) and photoperiod response (PPD). In the present study, allelic variation in the VRN1, VRN3, and PPD-A1 genes was investigated for 134 varieties of Triticum durum from different eco-geographic areas. It was shown that varieties from Russia and Ukraine have a specific allelic composition at the VRN genes, which in quantity and quality differed from European and American cultivars. A large number of varieties of T. durum from Russia carry the dominant Vrn-A1a.1 allele, previously identified mainly in hexaploid wheat. For some varieties from Eastern Europe and Asia, Vrn-A1i and vrn-A1b.3 recently revealed in wheat were also identified. Polymorphism of the VRN-B1 promoter region, distinguishing all three variants of this sequence (VRN-B1.f, VRN-B1.s, and VRN-B1.m), was detected. It was found that the dominant Vrn-B1c allele is commonly found in varieties of T. durum from Russia and Ukraine, but not Europe or USA. Furthermore, many Ukrainian and Russian varieties carry the dominant alleles of the both VRN-A1 and VRN-B1 genes simultaneously, while varieties from Europe and America carry the dominant allele of VRN-A1 alone. Finally, a high frequency of the Vrn-B3a allele, which previously was found only in some accessions of hexaploid wheat, was observed for varieties from Ukraine and Russia. It was revealed that the Ukrainian pool of T. durum varieties is currently the largest genetic source of the dominant Vrn-B3a allele in wheat in the worldwide.

Allelic Variation at the Vernalization Response (Vrn-1) and Photoperiod Sensitivity (Ppd-1) Genes and Their Association With the Development of Durum Wheat Landraces and Modern Cultivars

“…This result is in agreement with the clear preponderance of spring dominant alleles at the Vrn-A1 gene found previously in improved durum wheat varieties from Argentina, CIMMYT, France, Italy, and Hungary (Basualdo et al, 2015). The allele Vrn-A1a, found previously in durum wheat varieties from Russia (Muterko et al, 2016b) was not present in the germplasm analyzed here. In our study, all modern varieties except cv 'Claudio' carried the spring allele Vrn-A1c, while the allele Vrn-A1b was present in about half of the landraces, thus suggesting that breeding programs represented here have selected for the allele Vrn-A1c against Vrn-A1b.…”

“…Our results are not consistent with this hypothesis because the near fixation of the winter allele vrn-B1 in the two germplasm panels analyzed here suggests that mutations in the Vrn-A1 gene should have been the genetic basis underlying the spring growth habit of Mediterranean landraces and modern durum cultivars. The dominant allele Vrn-B1c, commonly found in durum wheats from Russia and Ukraine, but not from Europe or the United States (Muterko et al, 2016b), was also absent in our germplasm.…”

The Effect of Photoperiod Genes and Flowering Time on Yield and Yield Stability in Durum Wheat

“…Photoperiod sensitivity may be considered a mechanism for fine-tuning the optimal flowering time in a given environment within some mega-environments. In durum wheat, most varieties have the Vrn-A1c allele [29], corresponding to the spring growth habit, called the 'Langdon type', with rather rare alleles existing in genotypes from Russia, Ukraine, Azerbaijan and Hungary [30]. Therefore, once the appropriate Vrn alleles have been defined, a good strategy for adjusting flowering time to a given target environment would be to use a suitable combination of photoperiod sensitivity alleles.…”

Identification of Quantitative Trait Loci Relating to Flowering Time, Flag Leaf and Awn Characteristics in a Novel Triticum dicoccum Mapping Population

“…The physical position of the 7B QTL in Würschum et al [48] fell within the physical 1-LOD support interval of the QTL mapped on 7B in the present study. Variation in Vrn-B3 has been found to be prolific in durum wheat [50] and in T. dicoccum [51]. Vrn-B3 is considered to be linked exactly to the gene in Arabidopsis Flowering Locus T (FT) and is known to have some control on flowering time [52].…”