Identification And Expression Characteristics Of Viviparous -1 In Triticum Urartu

Pre-harvest sprouting (PHS) reduces the quality of wheat (Trilicum aestirum L.) and the economic value of the grain. Our previous studies have characterized the haplotypes of Vixiparous-1 A (Vp-lA) and its association with PHS resistance in both Chinese and CIMMYT wheats. As a potential A genome donor of common wheat, the diploid wheat related species Triticum urartu is an important genetic resource widely used in wheat improvement and breeding. The objective of this study was to identify and characterize the haplotypes of Vp-IA in Tritivum urartu and their phylogenetic relationship with other wheat related species. In total,4 novel Vp-lA haplotypes were explored among a collection of 20 Triticum urartu genotypes and designated as TuVp-lAbgi. TuVp-lAcgh,TuVp-lAdfi and TuVp-lAefi. respectively. The main differences between Vp-lAa and the newly identified haplotypes were the numbers of TTC repeat in third intron, and the deletions and SNPs in second and fifth introns.Semi-quantitative RT-PCR analysis showed that the expression levels of Vp-lA homologues were different in genotypes harboring these 4 haplotypes such as TuVp-lAbgi, TuVp-lAcgh, TuVp-lAdfi and TuVp-lAefi. of which TuVp-lAdfi had the most abundance of correctly spliced transcripts, while TuVp-lAbgi and TuVp-lAcgh had the least. Furthermore. the differences in transcript levels of the four genotypes were observed after ABA treatment. indicating their different responsiveness to ABA exposure. These results indicated that the indels in second, third and fifth intron regions Vp-IA affected its expression and its sensitivity to ABA. and thus seed dormancy,and identified a novel haplotype TuVp-lAdfi which might be useful in wheat improvement for PHS resistance. The phylogenetic tree analysis showed that the Vp-lA haplotypes from bread wheat and elite wheat had closer relationship with T.urartu than with T.monococcum and T. Bocoucum.