The autophagy‐related gene BcATG1 is involved in fungal development and pathogenesis in Botrytis cinerea

Abstract

Autophagy, a ubiquitous intracellular degradation process, is conserved from yeasts to humans. It serves as a major survival function during nutrient depletion stress and is crucial for correct growth and differentiation. In this study, we characterized an atg1 orthologue Bcatg1 in the necrotrophic plant pathogen Botrytis cinerea. Quantitative real-time polymerase chain reaction (qRT-PCR) assays showed that the expression of BcATG1 was up-regulated under carbon or nitrogen starvation conditions. BcATG1 could functionally restore the survival defects of the yeast ATG1 mutant during nitrogen starvation. Deletion of BcATG1 (ΔBcatg1) inhibited autophagosome accumulation in the vacuoles of nitrogen-starved cells. ΔBcatg1 was dramatically impaired in vegetative growth, conidiation and sclerotial formation. In addition, most conidia of ΔBcatg1 lost the capacity to form the appressorium infection structure and failed to penetrate onion epidermis. Pathogenicity assays showed that the virulence of ΔBcatg1 on different host plant tissues was drastically impaired, which was consistent with its inability to form an appressorium. Moreover, lipid droplet accumulation was significantly reduced in the conidia of ΔBcatg1, but the glycerol content was increased. All of the defects of ΔBcatg1 were complemented by re-introduction of an intact copy of the wild-type BcATG1 into the mutant. These results indicate that BcATG1 plays a critical role in numerous developmental processes and is essential to the pathogenesis of B. cinerea.

Transcriptome analysis and functional validation reveal a novel gene, BcCGF1, that enhances fungal virulence by promoting infection‐related development and host penetration

“…We then generated gene knockout (KO) mutants as previously described (Feng et al, 2017) and conducted pathogenicity assays. Consistent with previous findings (Schumacher et al, 2015;Ren et al, 2017), the mutants lacking BcATG1, BcLAE1, or BcVEL1 lost their virulence ( Figure S5). However, loss of individ-…”

“…The involvement of B. cinerea autophagy in securing a successful infection is likely via mediating its nutrition acquisition and development. These data also support the recent findings about the roles of autophagy in B. cinerea pathogenesis (Ren et al, 2017(Ren et al, , 2018a(Ren et al, , 2018bLiu et al, 2019a).…”

The Subtilisin-Like Protease Bcser2 Affects the Sclerotial Formation, Conidiation and Virulence of Botrytis cinerea

“…Autophagy has been shown to be involved in many life processes of fungi, including cellular differentiation, development, and virulence to host plants [46][47][48][49]. In B. cinerea, the autophagy-related genes BcATG1, BcATG4 and BcATG8 were also involved in the development and virulence [50][51][52]. Interestingly, we found that the phenotype of ∆Bcser2 is very similar to that of these autophagy-related genes in B. cinerea.…”

The Autophagy Gene BcATG8 Regulates the Vegetative Differentiation and Pathogenicity of Botrytis cinerea

“…in which autophagy has been verified to be blocked (25). The strain transformed with only the GFP gene showed an evenly diffused GFP signal in the cytoplasm of mycelia.…”

“…. The previous study we made in B. cinerea suggests that BcATG1 is involved in fungal development and pathogenesis (25). To further understand autophagy in B. cinerea, we isolated BcATG8, a yeast ATG8 homologue in B. cinerea, visualized the autophagy process using a fluorescent fusion protein, and further analyzed its function by a reverse genetic approach.…”