A maize viviparous 1 gene increases seed dormancy and preharvest sprouting tolerance in transgenic wheat

The viviparous-1 (Vp1) gene from maize encodes a transcription factor involved in abscisic acid (ABA) signaling that is associated with seed dormancy and preharvest sprouting (PHS). Mis-splicing of wheat homologous Vp1 transcripts has been considered the main factor causing PHS sensitivity in wheat. A maize Vp1 gene including its promoter and coding sequence was used for Agrobacterium tumefaciens mediated transformation of an elite wheat cultivar, Zheng9023. Plants expressing the Vp1 gene displayed a genetically stable, significantly enhanced seed dormancy and PHS tolerance. A significant reduction of α-amylase activity of mature grains was detected in all the transgenic wheat plants. Furthermore, quantitative real-time polymerase chain reactions revealed that more transcripts for the genes involved in VP1/ABA signaling, such as the genes coding for wheat ABA-insensitivity, malate oxidoreductase, peroxiredoxin, and late embryogenesis abundant proteins, were concomitantly accumulated during seed development in the transgenic wheat plants compared with the non-transgenic Zheng9023. These results indicated a highly functional compensation of the Vp1 gene in wheat by an alien homolog from maize, providing a promising approach to breed wheat cultivars with improved tolerance for PHS through a genetic engineering process.

► Heterologous expression of a maize Vp1 gene regulated by its own promoter in wheat.
► Enhancement of seed dormancy and PHS tolerance in wheat by genetic engineering.
► Seed dormancy and PHS tolerance closely correlated with α-amylase activity and expression of ABA signaling genes in transgenic wheat.
► Functional compensation of wheat Vp1 by a maize homolog.
► Generation of transgenic wheat using Pmi gene as selection marker mediated by Agrobacterium.