Mengru Dou ^1,2,3 Yuhang Li ^1,2,3 Yu Hao ^1,2,3 Kangzhuang Zhang ^1,2,3 Xiao Yin ^1,2,3 Zinuo Feng ^1,2,3 Xi Xu ^1,2,3 Qi Zhang ^1,2,3 Wenwu Bao ^1,2 Xi Chen ^1,2,3 Guotian LIU ^1,2,3 Yuejin Wang ^1,2,3 Ling Tian ^4* Yan Xu ^1,2,3*

• ¹ College of Horticulture, Northwest A&F University, Xianyang, China
• ² State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A and F University, Xianyang, Shaanxi Province, China
• ³ Key Laboratory of Horticultural Plant Biology and Germplasm Innovation, College of Horticulture, Northwest A&F University, Xianyang, Shaanxi, China
• ⁴ School of Management, Shenzhen Polytechnic, Shenzhen, Guangdong, China

Grape is of high economic value. Colletotrichum viniferum, a pathogen causing grape ripe rot and leaf spot, threatens grape production and quality. This study investigates the interplay between C. viniferum and different grapevine germplasms, V. vinifera cv. Thompson Seedless (TS), V. labrusca accession Beaumont (B) and V. piasezkii Liuba-8 (LB-8) were classified as high sensitive, moderate resistant and resistant to C. viniferum, respectively. Cytological study analysis reveals distinct differences between susceptible and resistant grapes post-inoculation, including faster pathogen development, longer germination tubes, normal appressoria of C. viniferum and absence of white secretions in the susceptible host grapevine. To understand the pathogenic mechanisms of C. viniferum, transcriptome sequencing was performed on the susceptible grapevine “TS” identifying 236 differentially expressed C. viniferum genes. These included 56 effectors, 36 carbohydrate genes, 5 P450 genes, and 10 genes involved in secondary metabolism. Fungal effectors are known as pivotal pathogenic factors that modulate plant immunity and affect disease development. Agrobacterium-mediated transient transformation in Nicotiana benthamiana screened 10 effectors (CvA13877, CvA01508, CvA05621, CvA00229, CvA07043, CvA05569, CvA12648, CvA02698, CvA14071 and CvA10999) that inhibited INF1 (infestans 1, P. infestans PAMP elicitor) induced cell death and 2 effectors (CvA02641 and CvA11478) that induced cell death. Additionally, transcriptome analysis of “TS” in response to C. viniferum identified differentially expressed grape genes related to plant hormone signaling (TGA, PR1, ETR, and ERF1/2), resveratrol biosynthesis genes (STS), phenylpropanoid biosynthesis genes (PAL and COMT), photosynthetic antenna proteins (Lhca and Lhcb), transcription factors (WRKY, NAC, MYB, ERF, GATA, bHLH and SBP), ROS (reactive oxygen species) clearance genes (CAT, GSH, POD and SOD), and disease-related genes (LRR, RPS2 and GST). This study highlights the potential functional diversity of C. viniferum effectors. Our findings lay a foundation for further research of infection mechanisms in Colletotrichum and identification of disease response targets in grape.