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Integration of light and jasmonate perception in the control of growth and defense

Carlos Ballare: IFEVA, University of Buenos Aires-CONICET

<div>Light signals, perceived through informational photoreceptors, are used by plants to detect and respond to the proximity of competitors. Low red:far-ratios (R:FR) in the canopy light reduce the proportion of phytochrome B (phyB) molecules that are in the active form, and promote the synthesis of growth-related hormones, including auxin and gibberellins, which in turn stimulate shoot elongation and other shade-avoidance responses. At the same time, recent research demonstrates that phyB is an important modulator of the two principal hormonal pathways that regulate plant immunity against herbivores and pathogens, i.e. the jasmonic-acid (JA) and the salicylic-acid pathways (SA). Low R:FR ratios down-regulate JA- and SA-induced defense responses. This down-regulation is thought to help the plant to efficiently redirect resources from defense to rapid growth under conditions of intense competition. In this presentation, I will discuss recent advances in the understanding of the mechanisms that link phyB with JA signaling, and explore the consequences for direct and indirect defenses. Unveiling the molecular links between photoreceptors and the regulators of plant immunity is important to generate a mechanistic framework to understand how plants deal with resource allocation trade-offs under natural conditions. This mechanistic understanding can be very useful to guide breeding programs aimed at increasing plant resistance to pests and pathogens in cultivated species.</div>