Isolation and characterization of Viviparous-1 genes in wheat cultivars with distinct ABA sensitivity and pre-harvest sprouting tolerance

Abstract

Pre-harvest sprouting (PHS) of wheat reduces the quality and economic value of grain, and increasing PHS tolerance is one of the most important traits in wheat breeding. Two new Vp-1B alleles related to PHS tolerance were identified on the 3BL chromosome of bread wheat and were designated Vp-1Bb and Vp-1Bc. Sequence analysis showed that Vp-1Bb has a 193 bp insertion and Vp-1Bc has a 83 bp deletion located in the third intron region of the Vp-1B gene, and that they shared 95.43% and 97.89% similarity, respectively, with the sequence of AJ400713 (Vp-1Ba) at the nucleotide level. Their sequences were deposited in the GenBank under the accession numbers DQ517493 and DQ517494. Semi-quantitative RT-PCR analysis showed that alternatively spliced transcripts of the Vp-1A, Vp-1B, and Vp-1D homologues were present and there were no differences in the splicing patterns or abundances of Vp-1A and Vp-1D from embryos 35 d after pollination between PHS-tolerant and -susceptible cultivars. Although Vp-1Ba, Vp-1Bb, and Vp-1Bc could each produce a set of transcripts, only one was correctly spliced and had the capacity to encode the full-length VP1 protein and was more highly expressed with Vp-1Bb and Vp-1Bc than with Vp-1Ba. Comparison of the expression patterns of Vp-1Ba, Vp-1Bb, and Vp-1Bc on different days after pollination also revealed that the expression of these genes was developmentally regulated. Furthermore, genotypes with different levels of tolerance to PHS respond differently to ABA exposure and differences in transcript levels of Vp-1Ba, Vp-1Bb, and Vp-1Bc were observed after ABA treatment. The results indicated that insertion or deletion in the third intron region might affect the expression of the Vp-1B gene and its sensitivity to ABA, and thus resistance to PHS.

What can the Viviparous-1 gene tell us about wheat pre-harvest sprouting?

“…Three white-grained genotypes with different levels of PHS tolerance were selected and used for PCR amplification of Vp-1A, Vp-1B and Vp-1D; Zhongyou 9507, a PHS susceptible cultivar, Yongchuanbaimai, a typical PHS tolerant Chinese landrace, and Xinong 979, a PHS tolerant cultivar (Zhang et al 2006a;Yang et al 2007a).…”

“…Twelve pairs of primers were designed to amplify the fragments of the Vp-1A, Vp-1B and Vp-1D genes, respectively (Yang et al 2007b), among them, only one polymorphic primer Vp-1BF 3 /R 3 was used in this study (Table 1). Another three pairs of genome-specific primers, RTVp-1AF/R, RTVp-1BF/R and RTVp-1DF/R, were designed to amplify the Vp-1A, Vp-1B and Vp-1D cDNA, respectively (Yang et al 2007a), among them, only RTVp-1BF/R was used in this study (Table 1). The expected size of the PCR product of 'functional transcript' is 672 bp as indicated in Table 1.…”

Differential expression of three ABA-insensitive five binding protein (AFP)-like genes in wheat

“…According to studies investigating the chromosomal location and the quantitative trait loci (QTL) of the dormancy genes of wheat, many genes that act positively or negatively in the formation of dormancy have been reported and located on the chromosomes of homoeologous groups 2, 3, 4 and 5 Flintham et al 2002;Noda et al, 2002). Wheat Vp1 genes on the chromosomes of homoeologous group 3, orthologs of AtABI3, have been isolated and might function as a positive regulator for the development of grain dormancy (Nakamura and Toyama 2001;Wilkinson et al 2005;Yang et al 2007). TaABF, an ortholog of AtABI5, was also reported to be involved in the maintenance of grain dormancy during imbibition (Johnson et al 2002).…”

Approaches to improve wheat grain quality: breeding for falling number

“…У мягкой пшеницы установлен множественный алле-лизм Vp-1-генов (Yang et al, 2007;Xia et al, 2009;Chang et al, 2010;Yang et al, 2014а, b). Периоды покоя семян и УкПП наиболее тесно ассоциированы с рядом аллелей Vp-1B (Xia et al, 2009;Chang et al, 2010), а также с Vp-1A-локусом (Chang et al, 2011).…”