Expression of a GDP-L-galactose phosphorylase-like gene in a Chinese wild Vitis species induces responses to Erysiphe necator and defense signaling molecules.

Using rapid amplification of cDNA ends, a full-length cDNA sequence of a GDP-L-galactose phosphorylase-like gene was isolated from leaves infected by Erysiphe necator in the Chinese wild (Vitis pseudoreticulata) clone, 'Baihe-35-1', an E. necator-resistant genotype. The full-length cDNA, designated as VpVTC, comprised 1943 bp and putatively encodes a 453-amino acid polypeptide containing an HIT motif. The deduced amino acid sequence showed high similarity with that of VTC genes from other plants. The expression of VpVTC, determined by reverse transcriptase-polymerase chain reaction, was induced by E. necator and defense signaling molecules, including salicylic acid, methyl jasmonate, and ethephon, in 'Baihe-35-1', the V. quinquangularis genotype 'Shang-24', and the E. necator-susceptible V. pseudoreticulata genotype, 'Hunan-1'. Transcript levels of VpVTC correlated well with the degree of disease resistance in the 3 genotypes. Maximum induction of VpVTC by E. necator (>7-fold at 96 h post-inoculation) occurred in 'Baihe-35-1', which also showed the fastest response to signaling molecules. Upregulating the expression of VpVTC in 'Baihe-35-1' resulted in a gradual increase in the ascorbic acid concentration of leaves inoculated with E. necator. Furthermore, VpVTC was expressed in leaves, stems, inflorescence, tendrils, and fruit at all developmental stages, with the highest level occurring in fruit 35 days after flowering.

Analysis of genetic diversity among Chinese wild Vitis species revealed with SSR and SRAP markers.

The genetic diversity among 80 Vitis materials including 62 indigenous accessions of 17 wild Vitis species in China and 7 interspecific hybrids, 10 V. vinifera L. cultivars, and 1 V. riparia Michaux were evaluated by simple sequence repeat and sequence-related amplified polymorphism markers. A total of 10 simple sequence repeat primers and 11 sequence-related amplified polymorphism primer combinations were amplified, and 260 bands were generated, of which 252 were polymorphic with an average polymorphism rate of 97.02%. Genetic relationships among the different Vitis species indicated that V. ficifolia and V. yeshanensis could be considered a separate species. As for the 4 major ecogeographic regions of Chinese wild Vitis species, the genetic diversities of Chinese wild Vitis species from the Qinling Mountain region (H = 0.1947, I = 0.3067) and the mid-downstream Yangtze River region (H = 0.1834, I = 0.2925) were higher, with results suggesting that these regions may be one of the major centers of Vitis origin. An understanding of the genetic diversity of these Chinese wild Vitis species could provide the theoretical foundation for further protection and reasonable utilization in grape breeding.