Navigating through the plant immune signaling network: Search for hormonal crosstalk regulators

Abstract

In nature, plants are continuously exposed to various pathogens and herbivorous insects. Although plants have evolved specific mechanisms to defend themselves against these attackers, the global crop losses due to these attackers corresponds to billions of euros annually. It is of great importance to identify genes that underlie the induction of plant defenses to provide novel strategies for disease-resistant crop breeding. Two major players in induced plant defenses are the phytohormones salicylic acid (SA) and jasmonic acid (JA). Recently, growth hormones like ethylene and abscisic acid (ABA) have been recognized as modulators of SA- and JA-mediated defenses in the plant immune signaling network. The signaling pathways of growth and defense are interconnected in a complex signaling network. Antagonistic and synergistic interactions, also known as crosstalk, between the various hormones has been well studied. However, the molecular mechanisms by which hormone signaling pathways interact to promote crosstalk remains largely unclear. It is assumed that crosstalk supports the plant to minimize fitness costs when defense is activated. However, evidence for this role of crosstalk in trade-off between defense and growth is lacking. Therefore, the aims of this proposal are (1) to identify genes that regulate crosstalk on JA signaling with the use of natural accessions of Arabidopsis thaliana as “resource” for genetic and phenotypic variation and (2) to analyze the effect of crosstalk, with the use of mutant and overexpressors, on (a) plant resistance and (b) plant fitness when facing single and multiple attackers.