Transient overexpression and silencing of tomato SlGLP11-1 gene reveal its crucial role in mediating ROS homeostasis driven disease resistance

Abstract Germin and germin- like proteins (GLPs) are known to play various roles in plant development and in response to biotic and abiotic stress. Many GLPs have been reported to show differential expression in response to pathogen infections, indicating their direct roles in host- pathogen interactions. Despite their significant roles in plant immunity, the tomato ( Solanum lycopersicum L.) GLP members have not been studied comprehensively at the genome- wide scale. Also, very few reports exist on the functions and activities of tomato GLP gene family members. In this study, GLP family members in tomato were analysed and a standardised nomenclature for tomato GLP genes was defined. The chromosomal distribution of GLP genes in tomato was determined, and a phylogenetic analysis was performed. In addition, the in silico subcellular localization of GLPs in tomato was predicted, and gene expression was examined in response to different phytohormone treatments and pathogen infection. Finally, we identified candidate pathogen- responsive SlGLPs and functionally characterized SlGLP11-1 . Transient overexpression of SlGLP11-1 in Nicotiana leaves enhanced resistance against Botrytis cinerea . Similarly transient silencing of SlGLP11-1 by virus induced gene silencing (VIGS) in tomato leaves increased susceptibility to Botrytis cinerea infection. We also, estimated endogenous H 2 O 2 levels and catalase activity in the transient SlGLP11- 1 overexpressed and silenced leaves of Nicotiana benthamiana and tomato respectively, all with and without Botrytis infection. Our results establish that SlGLP11 -1 functions as a positive regulator of ROS-mediated plant defence by promoting H 2 O 2 accumulation during both basal and pathogen challenged conditions, with catalase activity tracking H 2 O 2 levels as a secondary antioxidant response. This study will serve as a foundation for future functional investigations of tomato GLP family members playing role in the plant immunity.