SlWRKY22 and SlWRKY25 are positives regulators of plant immunity

RAMOS, ROMINA N.; NING ZHANG ; MARTIN, GREGORY B.; POMBO, MARINA A.; ROSLI, HERNAN G.

Santa Fe

Congreso; XXXIII Argentinian meeting of plant physiology; 2021

Plants defend themselves against pathogens using a two layered immune system. Pattern-triggered immunity (PTI) is activated upon recognition of microbe-associated molecular patterns (MAMPs). Particularly in tomato, the detection of bacterial flagellin relies on the perception of two MAMPs: flg22, that is recognized by the receptor flagellin sensing 2 (FLS2) and flgII-28, by flagellin sensing 3 (FLS3). Virulent bacteria as Pseudomonas syringae pv. tomato (Pst), can deliver effector proteins into the plant cell to promote susceptibility. However, some plants posses resistance (R) proteins that recognize specific effectors leading to the activation of effector-triggered immunity (ETI). Resistant tomatoes such as Río Grande-PtoR (RG-PtoR) recognize two Pst effectors (AvrPto and AvrPtoB) through Pto/Prf complex and then activate ETI.In a previous study, we confirmed that SlWRKY22 and SlWRKY25 transcription factors (TF) are positives regulators of plant immunity against bacterial and potentially non-bacterial pathogens in Nicotiana benthamiana (Nb). Using CRISPR-Cas technique, three knock out tomato lines were generated for both TF. These plants showed more symptoms of disease when challenged with Pst DC3000 ∆avrPto∆avrPtoB. To confirm these results, we evaluated bacterial growth in leaf tissue and observed higher bacterial titer in ∆SlWRKY22/25 plants. Also we performed a callose deposition assay and fewer callose deposits was observed when these TF are knock out. Also, to probe the subcellular localization properties of these TF their CDSs were cloned fusion to GFP and RFP respectively. Microscopic observation showed a co-localization of SlWRKY22 and SlWRKY25 at the nuclei in Nb. Together, our results indicate the participation of both WRKY TFs as positive regulators of plant immunity.