Genetic diversity and breeding value of synthetic hexaploid wheat introduced into the VIR collection

Abstract

For the successful development of wheat breeding in Russia, a genetically diverse and well-characterized starting material, mainly stored at the VIR collection, is needed. To replenish the collection, 36 lines (accessions) of synthetic hexaploid wheat (SHWs) developed at CIMMYT by crossing Triticum durum with Aegilops tauschii were studied. Our research was aimed at studying the SHWs using a complex of morphological and economically valuable traits in the environments of European Russia’s northwestern part (E30°, N59°), evaluating the reaction of the SHWs to a photoperiod and determining their genetic heterogeneity and similarities by gliadins as biochemical markers. The results showed that the variability of different traits for SHWs fits into the framework of the genus Triticum, and so SHWs can be classified as poorly domesticated forms. Their distinctive feature, valuable for wheat breeding, is a large weight of a thousand grains (up to 60.6 g). This trait was characterized by a low degree of variability and a low correlation with other traits. The reaction of wheat plants to the length of the day is crucial for their transition from vegetative to reproductive development. The SHWs studied differed from common wheat and one another by responses to the short day and by the length of the ‘emergence-heading’ phase if they grew under the conditions of a long day. The delay in the development of plants with a short photoperiod ranged from 5.4 to 53.8 days. On a long day, the duration of the ‘emergence-heading’ phase varied from 39.5 to 53.9 days. A possible genetic basis for the differences identified is discussed. To assess the diversity of SHWs, we also used gliadin proteins as informative biochemical markers. It was revealed that 21 SHWs were homogeneous, and the rest, heterogeneous. Forty-four different biotypes were found for the SHWs studied, from which 36 were unique. Relationships between biotypes have been demonstrated using cluster analysis. It should be noted that 13 SHWs were unstable. In each of them, some plants differed from the others in terms of a complex of morphological characters, reaction to a photoperiod, and gliadin patterns. It is possible that the instability of accessions is the result of genome rearrangement in SHWs. SHW accessions and the forms isolated from them are considered as sources of new genetic variability to improve common wheat.