Genetic mapping and survey of powdery mildew resistance in the wild Central Asian ancestor of cultivated grapevines in Central Asia

Abstract

Cultivated grapevines (Vitis vinifera) lack resistance to powdery mildew (PM) with few exceptions. Resistance to this pathogen within V. vinifera has been reported in earlier studies and identified as the Ren1 locus in two Central Asian table grape accessions. Other PM-resistant cultivated varieties and accessions of the wild ancestor V. vinifera subsp. sylvestris were soon identified raising questions regarding the origin of the resistance. In this study, F1 breeding populations were developed with a PM susceptible V. vinifera subsp. vinifera breeding line and a PM-resistant subsp. sylvestris accession. Genotyping was carried out with five Ren1 locus linked SSR markers. A PM resistance locus explaining up to 96% of the phenotypic variation was identified in the same genomic position, where the Ren1 locus was previously reported. New SSR marker alleles linked with the resistance locus were identified. We report results of PM resistance in multiple accessions of subsp. sylvestris collected as seed lots or cuttings from five countries in the Caucasus and Central Asia. A total of 20 females from 11 seed lots and 19 males from nine seed lots collected from Georgia, Armenia, and Azerbaijan were resistant to PM. Three male and one female plant collected as cuttings from Afghanistan and Iran were also resistant to PM. Allelic analysis of markers linked with the Ren1 locus in conjunction with disease evaluation data found a high diversity of allelic haplotypes, which are only possible via recombination events occurring over a long time period. Sequence analysis of two alleles of the SSR marker that cosegregates with the resistance found SNPs that were present in the wild progenitor and in cultivated forms. Variable levels of PM resistance among the tested accessions were also observed. These lines of evidence suggest that the powdery mildew fungus may have been present in Asia for a longer time than currently thought, giving the wild progenitor V. vinifera subsp. sylvestris time to coevolve with and develop resistance to this pathogen.

Construction of A High-Density Genetic Map And Detection of A Major QTL of Resistance To Powdery Mildew (Erysiphe Necator Sch.) In Caucasian Grapes (Vitis Vinifera L.)

“…However, only an extended phenotypic survey in the same experimental conditions, together with the collected molecular data, could provide clearer insights into the spread of resistance to E. necator in the Caucasian cultivated germplasm. Currently, our genetic ndings are consistent with the Riaz et al [50] study, which identi ed in the same genomic region of chr 13 of a Caucasian V. vinifera subsp. sylvestris a resistance QTL to E. necator.…”

“…Our research, in addition to other studies, identi ed the resistance to E. necator in many V. vinifera grapevines of different geographic areas (Caucasus and Central Asia) and collected evidence that its inheritance is shared by wild and cultivated V. vinifera subspecies [18, 19,24,50]. This information and the long history of grapes isolation in the Caucasus region [51,52] suggests that the resistance trait might have been inherited from a V. vinifera progenitor thousands of years ago and conserved in Caucasian cultivars until today.…”

“…This hypothesis could explain the presence of resistance to E. necator in V. vinifera, and also in other Asian Vitis spp. [18, 19,24,50], with the co-evolution theory. However, the Gur et al [57] suggestion is in contrast to common notions on E. necator origin and centres of differentiation [e.g.…”

“…Phenotypic information collected in our research often showed distinct responses to E. necator of Caucasian grapevines (in particular 'Shavtsitska') and 'Kishmish vatkana'. However, the phenotypic resistance of the Caucasian and Central Asian grape accessions, due to the trait variations associated to the genes [24,39,50], does not allow to clearly con rm whether the genetic basis of resistances is different or not.…”

Comprehensive analysis of SSRs and database construction using all complete gene-coding sequences in major horticultural and representative plants

“…The development of bioinformatics technology has enabled the development of SSR markers for many species 29 – 31 . Recently, there have been many reports on SSR development and application 32 – 38 . These studies have confirmed that SSRs are the classic, popular molecular markers used in plant science.…”