The world's rapidly increasing population and the urgent need to increase food production necessitate the production of highly adapted and high-yielding wheat cultivars.Vernalization genes determine the winter versus spring growth habit in wheat and play a decisive role in its adaptation to a wide range of environments.Early flowering lets plants fill their grains before the onset of late-season drought or heat stress,which can cause considerable yield losses.Due to predicted global temperature increases in future early-flowering cultivars may increase yield and stabilize food production.Wild relatives of wheat have proven to be valuable source of new genes and desirable traits.This study describes the ability of added chromosomes from wheat wild relative Leymus racemosus to eliminate the vernalization requirement and promote early flowering.We evaluated wheat–Leymus chromosome introgression lines under field conditions in Sudan and Japan and under growth chamber conditions.In Sudan,two chromosome addition lines flowered four weeks earlier than their wheat background,'Chinese Spring',whereas they were comparable to Chinese Spring in Japan.One substitution line flowered later than all tested genotypes in Sudan and Japan.Under long-day conditions in the growth chamber,the two addition lines and the substitution line flowered significantly earlier than Chinese Spring.Screening of allelic variations of vernalization and photoperiod genes indicated that Chinese Spring harbors only the dominants allele Vrn-D1 whereas the three lines had the dominant allele Vrn-D1in addition to an insertion at the Vrn-A1 1ocus.No allelic variation at the other Vrn and Ppd loci was detected.The early flowering of the three lines is attributed to the presence of an insertion at the Vrn-A1locus.Identification of such allele for promoting a spring growth habit will contribute to breeding cultivars for specific environments and to developing spring populations that lack vernalization requirements.
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