Streamlining the defense mechanism involving miRNA/mRNA and phytohormones during mycorrhiza-fusarium infecting tomato roots

Simplificando o mecanismo de defesa envolvendo miRNA/mRNA e fito-hormônios durante infecção por micorriza-Fusarium em raízes de tomateiro

Abstract

This study was carried out to identify the relationship between miRNAs/ targets and phytohormone-related genes associated with Rhizophagus irregularis/ F. oxysporum f. sp. lycopersici (Fol) interaction through post-infection of tomato roots at different stages. Furthermore, to address the role of miRNA-mediated families in regulating plant hormone crosstalk during plant-microbe interactions, including salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), auxin (AUX) and 5 ethylene (ET). In this study, Expression levels of ethylene-responsive genes reflect antagonism between arbuscular mycorrhizal fungi (AMF) and ET, re-modulating immunoregulatory capacity in tomato. On the other hand, our data reinforce that overexpression of AP2 and ERF1 delay senescence in Fol-infected tomato plants by downregulating the expression level of SPL3. Moreover, a balance between TCP4, miR164, and miR319b transcript levels suggests that their interaction attenuates senescence under AMF infection.

Measurements of phytohormone production under AMF/Fol infection at 30 days post-inoculation (dpi) showed significantly lower hormone production in the resistant genotype (Heinz 'Hz') compared to the susceptible genotype (Castle Rock 'CR') by 36, 17, and 14% for ET, ABA, and JA, respectively. These findings potentially imply that modifications in Heinz’s hormonal signaling are prompting host changes, which lead to decreased phytohormone levels. This study provides an applied basis for further research on the molecular mechanism and challenges associated with the continuous cropping of tomato by R. irregulari under the deleterious effects of Fusarium on late stages of root infection.

Keywords:
Rhizophagus irregulari; Fusarium oxysporum; small RNAs (miRNAs); jasmonic acid; salicylic acid; Solananum lycopersicum