Identification of mildew resistance in wild and cultivated Central Asian grape germplasm

Summaira Riaz,Thierry Lacombe,Alan C Tenscher,Valerie Laucou,Jean-Michel Boursiquot,M Andrew Walker,Gerald S Dangl

doi:10.1186/1471-2229-13-149

Abstract

BackgroundCultivated grapevines, Vitis vinifera subsp. sativa, evolved from their wild relative, V. vinifera subsp. sylvestris. They were domesticated in Central Asia in the absence of the powdery mildew fungus, Erysiphe necator, which is thought to have originated in North America. However, powdery mildew resistance has previously been discovered in two Central Asian cultivars and in Chinese Vitis species.ResultsA set of 380 unique genotypes were evaluated with data generated from 34 simple sequence repeat (SSR) markers. The set included 306 V. vinifera cultivars, 40 accessions of V. vinifera subsp. sylvestris, and 34 accessions of Vitis species from northern Pakistan, Afghanistan and China. Based on the presence of four SSR alleles previously identified as linked to the powdery mildew resistance locus, Ren1, 10 new mildew resistant genotypes were identified in the test set: eight were V. vinifera cultivars and two were V. vinifera subsp. sylvestris based on flower and seed morphology. Sequence comparison of a 620 bp region that includes the Ren1-linked allele (143 bp) of the co-segregating SSR marker SC8-0071-014, revealed that the ten newly identified genotypes have sequences that are essentially identical to the previously identified mildew resistant V. vinifera cultivars: ‘Kishmish vatkana’ and ‘Karadzhandal’. Kinship analysis determined that three of the newly identified powdery mildew resistant accessions had a relationship with ‘Kishmish vatkana’ and ‘Karadzhandal’, and that six were not related to any other accession in this study set. Clustering procedures assigned accessions into three groups: 1) Chinese species; 2) a mixed group of cultivated and wild V. vinifera; and 3) table grape cultivars, including nine of the powdery mildew resistant accessions. Gene flow was detected among the groups.ConclusionsThis study provides evidence that powdery mildew resistance is present in V. vinifera subsp. sylvestris, the dioecious wild progenitor of the cultivated grape. Four first-degree parent progeny relationships were discovered among the hermaphroditic powdery mildew resistant cultivars, supporting the existence of intentional grape breeding efforts. Although several Chinese grape species are resistant to powdery mildew, no direct genetic link to the resistance found in V. vinifera could be established.

Highlights

Cultivated grapevines, Vitis vinifera subsp. sativa, evolved from their wild relative, V. vinifera subsp. sylvestris
It is widely accepted that the cultivated form of V. vinifera subsp. sativa derived from its wild form V. vinifera subsp. sylvestris [5,6], which was once spread widely across Western Europe, the Mediterranean, the Caucasus, Himalaya and Hindu Kush mountain ranges, and Central Asia [7,8,9,10]
We discovered that powdery mildew resistance is present in two V. vinifera subsp. sylvestris accessions, a taxon considered to be the progenitor of the cultivated form sativa

Summary

Introduction

Cultivated grapevines, Vitis vinifera subsp. sativa, evolved from their wild relative, V. vinifera subsp. sylvestris. The detection of resistance to Erysiphe necator, the causal agent of grape powdery mildew, in two cultivars of Vitis vinifera from Central Asia [1,2] was intriguing given that this fungus was thought to have co-evolved with North American grape species, and that all V. vinifera cultivars were considered to be susceptible to this fungus. This discovery suggests that powdery mildew resistance is. Seeds may have been the more common means of propagation early in the cultivation of grapes as they were easier to transport over large distances and intentional and unintentional crosses generated great diversity within the cultivated types [21]

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