Abstract
Botrytis cinerea is a major grapevine (Vitis spp.) pathogen, but some genotypes differ in their degree of resistance. For example, the Vitis vinifera cultivar Red Globe (RG) is highly susceptible, but V. amurensis Rupr Shuangyou (SY) is highly resistant. Here, we used RNA sequencing analysis to characterize the transcriptome responses of these two genotypes to B. cinerea inoculation at an early infection stage. Approximately a quarter of the genes in RG presented significant changes in transcript levels during infection, the number of which was greater than that in the SY leaves. The genes differentially expressed between infected leaves of SY and RG included those associated with cell surface structure, oxidation, cell death and C/N metabolism. We found evidence that an imbalance in the levels of reactive oxygen species (ROS) and redox homeostasis probably contributed to the susceptibility of RG to B. cinerea. SY leaves had strong antioxidant capacities and improved ROS homeostasis following infection. Regulatory network prediction suggested that WRKY and MYB transcription factors are associated with the abscisic acid pathway. Weighted gene correlation network analysis highlighted preinfection features of SY that might contribute to its increased resistance. Moreover, overexpression of VaWRKY10 in Arabidopsis thaliana and V. vinifera Thompson Seedless enhanced resistance to B. cinerea. Collectively, our study provides a high-resolution view of the transcriptional changes of grapevine in response to B. cinerea infection and novel insights into the underlying resistance mechanisms.
Highlights
Introduction The necrotrophic fungusBotrytis cinerea is the causal agent of gray mold disease in grape (Vitis vinifera), which causes major losses in quality, yield and economic value[1]
On Red Globe (RG) leaves inoculated with B. cinerea, conidial germination occurred at 4 hpi, and their numbers subsequently continued to increase, with appressoria penetrating the leaf surface followed by successful infection occurring from 8 hpi onward (Fig. 1b)
Lesions were observed from 18 hpi and spread rapidly from 36 hpi on RG-infected leaves (Fig. 1c); more than half of the B. cinerea conidia had germinated at 18 hpi, and the infection rate reached 48% at 36 hpi (Fig. 1b and Supplemental Table 1A); in contrast, there were almost no lesions and much lower rates of germination and infection on the SY leaves at 36 hpi (Fig. 1b, c and Supplemental Table 1A)
Summary
Botrytis cinerea is the causal agent of gray mold disease in grape (Vitis vinifera), which causes major losses in quality, yield and economic value[1]. The primary contact of B. cinerea with its host takes place at the cell surface, where plant responses are initiated. Factors that affect host resistance include the capacity to maintain cell wall integrity and the generation and accumulation of reactive oxygen species (ROS)[2]. (hours post-inoculation)), host cell death and necrotic host tissue will occur[6]. Leaves of different Vitis genotypes that are classified as resistant to B. cinerea have been reported to display increased antioxidant capacity and exhibit increased tolerance to oxidative stress caused by B. cinerea[7,8]
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