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Article|01 Aug 2020|OPEN
CRISPR/Cas9-mediated mutagenesis of VvMLO3 results in enhanced resistance to powdery mildew in grapevine (Vitis vinifera)
Dong-Yan Wan1,2, Ye Guo1,2, Yuan Cheng1,2, Yang Hu1,2, Shunyuan Xiao3, Yuejin Wang1,2 & Ying-Qiang Wen1,2,
1State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100 Shaanxi, China
2Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling 712100 Shaanxi, China
3Institute for Bioscience and Biotechnology Research & Department of Plant Sciences and Landscape Architecture, University of Maryland College Park, Rockville, MD 20850, USA

Horticulture Research 7,
Article number: 20116 (2020)
doi: 10.1038/hortres.2020.116
Views: 114

Received: 24 Apr 2020
Revised: 08 May 2020
Accepted: 12 May 2020
Published online: 01 Aug 2020

Abstract

Grapevine (Vitis vinifera), one of the most economically important fruit crops in the world, suffers significant yield losses from powdery mildew, a major fungal disease caused by Erysiphe necator. In addition to suppressing host immunity, phytopathogens modulate host proteins termed susceptibility (S) factors to promote their proliferation in plants. In this study, CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) technology was used to enable the targeted mutagenesis of MLO (mildew resistance Locus O) family genes that are thought to serve as S factors for powdery mildew fungi. Small deletions or insertions were induced in one or both alleles of two grapevine MLO genes, VvMLO3 and VvMLO4, in the transgenic plantlets of the powdery mildew-susceptible cultivar Thompson Seedless. The editing efficiency achieved with different CRISPR/Cas9 constructs varied from 0 to 38.5%. Among the 20 VvMLO3/4-edited lines obtained, one was homozygous for a single mutation, three harbored biallelic mutations, seven were heterozygous for the mutations, and nine were chimeric, as indicated by the presence of more than two mutated alleles in each line. Six of the 20 VvMLO3/4-edited grapevine lines showed normal growth, while the remaining lines exhibited senescence-like chlorosis and necrosis. Importantly, four VvMLO3-edited lines showed enhanced resistance to powdery mildew, which was associated with host cell death, cell wall apposition (CWA) and H2O2 accumulation. Taken together, our results demonstrate that CRISPR/Cas9 genome-editing technology can be successfully used to induce targeted mutations in genes of interest to improve traits of economic importance, such as disease resistance in grapevines.