Salicylic acid signaling pathway as key player in the early activation of immune responses in maize

AGOSTINI, R.B.; POSTIGO, A.; RIUS, S.P.; CAMPOS BERMUDEZ, V.A.; VARGAS, W.A.

Paraná

Congreso; 54th Annual Meeting Agentine Society for Biochemistry and Molecular Biology; 2018

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The fungus Fusarium verticillioides is the main causal agent of maize ear rot and also produces massive amounts of the fumonisins, which have deleterious effects on humans and farm animals. One of the strategies to control this pathogen is biological control, through the use of non-pathogenic fungal species, such as members of Trichoderma genus. These fungus have been proved to be antagonist agents able to control fungal pathogens, to be plant growth promoters, improving and maintaining soil productivity, and can also stimulate local and distant immune responses (Induced Systemic Resistance, ISR) to prevent future pathogenic attacks.Thus, the focus of our research was to globally explore the early regulatory events modulated by ISR in silks from maize plants inoculated with Trichoderma atroviride and challenged with F. verticillioides, through a transcriptional and hormonal approach. For this, we carried out comparative tests of transcriptional expression using the RNA-seq technique and quantified the hormonal levels of salicylic acid (SA), abscisic acid and jasmonic acid through HPLC/MS in maize silks.Our transcriptome analysis, together with the hormone quantitative determinations performed, also shed some light on the role of hormones in the regulation of immune responses in maize silks after ISR activation. The results show a decrease in the SA levels during the pathogen infection in inoculated plants with Trichoderma and also an increase in the gene expression involved in the SA signaling pathway in maize silks. It is likely that, in maize silks, SA acts as a central signaling element to mediate local and systemic activation of defenses.