Effect of Salicylic Acid priming on the expression of Susceptible genes in Zingiber–Pythium interactions

Ginger soft rot, caused by the soilborne oomycete pathogen Pythium myriotylum, is a devastating disease that poses a major threat to commercial ginger production in India. P. myriotylum infects all parts of the ginger, including the roots, rhizomes, pseudostems and sprouts, leading to huge economic loss. Previous research works have identified several candidate genes in host plants that are differentially expressed during such pathogen attacks, and which eventually exacerbate disease severity. At present, the management of such diseases caused by phytopathogens in commercial crops mainly relies on the use of chemical agents. These offer several drawbacks, including the hazardous nature of chemical agents, resulting in detrimental effects on nature and human health. These limitations shed light on the evaluation of prospects for novel eco-friendly approaches in combating this pathogen. However, to address these concerns, it is necessary to identify the exact molecular mechanisms that drive host plants prone to P. myriotylum ingression and subsequent infection. In this study, one-month-old healthy ginger plants were primed by the foliar application of Salicylic Acid (SA) at optimized concentrations. The Disease Severity Index was calculated to examine the impact of pathogen inoculation. Biochemical investigations evaluated carotenoid, lignin and total phenolic content in plants, which play a pivotal role in pathogen resistance. Furthermore, the temporal gene expression analysis was carried out to assess the effect of SA on susceptibility genes. Results revealed that the SA-primed plants were more susceptible to infection upon pathogen inoculation. This was accompanied by altered levels of carotenoids, total phenolics and lignin contents in treated plants. Moreover, a real-time analysis of the susceptibility genes depicted enhanced expression levels in treated plants compared to control plants. This study will help to identify the expression of susceptible genes during P. myriotylum attack, which can be silenced using gene silencing methods in future to induce resistance in cultivable ginger.