SlWRKY30, a positive regulator of resistance to Meloidogyne incognita in Solanum lycopersicum

WRKY transcription factors play important roles in plant biological stress responses. Through RNA-seq, SlWRKY30 was shown to be differentially expressed in Mi-1- and Mi-3-resistant tomato lines after inoculation with Meloidogyne incognita. Bioinformatics analysis and expression profiling of roots from different lines revealed that this gene may serve as a key node for disease resistance regulation. This study employed VIGS to investigate whether the silencing of SlWRKY30 could affect the susceptibility of ‘AC’ (mi-1/mi-1) susceptible line and ‘18,060′ (Mi-1/Mi-1) resistant line to M. incognita. Subcellular localization analysis indicated that the protein encoded by this gene is located in the nucleus. Its overexpression in tomato significantly increased disease resistance, and the tomato plant’s resistance level increased from highly susceptible to resistant. Indirectly, these findings suggested that the regulation of resistance by SlWRKY30 might occur downstream of the Mi-mediated process or that the signal pathway involved by SlWRKY30 was different from that mediated by Mi. Combined with the measurement of growth (plant height, stem diameter, leaf area, etc.) and physiological (soluble sugars and proteins, root activity, etc.) indicators, these findings further clarify the role of SlWRKY30 as a positive regulatory factor in tomato defense against M. incognita. A preliminary exploration of metabolic signals revealed that SlWRKY30 may stimulate different types of signaling, such as salicylic acid, jasmonic acid and brassinosteroid signaling, etc., and may synergistically regulate reactive oxygen species accumulation through influencing scavenging enzyme activity, hindering the formation of feeding sites and ultimately leading to a reduction in root galls growth. To our knowledge, SlWRKY30 exhibits significant potential for enhancing tomato resistance to root-knot nematodes and holds great value in breeding applications.