The woody plant-degrading pathogen Lasiodiplodia theobromae effector LtCre1 targets the grapevine sugar signaling protein VvRHIP1 to suppress host immunity.

Lasiodiplodia theobromae is a causal agent of Botryosphaeria dieback, which seriously threatens grapevine production worldwide. Plant pathogens secrete diverse effectors to suppress host immune responses and promote infection progression. However, the mechanisms underlying the manipulation of host immunity by L. theobromae effectors are poorly understood. We characterized LtCre1, a L. theobromae effector that suppresses BAX-triggered cell death in Nicotiana benthamiana. RNAi silencing or overexpression of LtCre1 in L. theobromae showed either impaired or increased virulence, respectively. Ectopic expression of LtCre1 increased N. benthamiana susceptibility. These results suggest that LtCre1 is as an essential virulence factor for L. theobromae. Protein-protein interaction studies revealed that LtCre1 interacts with grapevine RGS1-HXK1-interacting protein 1 (VvRHIP1). Ectopic overexpression of VvRHIP1 reduced L. theobromae infection, suggesting that VvRHIP1 enhances plant immunity against L. theobromae. LtCre1 disrupts the formation of the VvRHIP1-VvRGS1 complex and participates in regulating the plant sugar signaling pathway. Thus, our results suggest that L. theobromae LtCre1 targets the grapevine VvRHIP1 to manipulate the sugar signaling pathway, probably by disrupting the association of the VvRHIP1-VvRGS1 complex.