Phytochrome B regulates systemic signaling of defense response in Arabidopsis

MORENO JE; ETCHEVERS L

Cordoba

Congreso; SAIB 2016; 2016

SAIB

Phytochromes are a conserved group of photoreceptors that control multiple aspects of plant architecture and health. Phytochromes (Phy) oscillate between an active and inactive state depending on the red (R, 680 nm) to far red (FR, 730 nm) ratio of the incoming light. The R:FR ratio is translated into information by Phy to let the plant perceive and outcompete future competitors through the initiation of the shade avoidance syndrome (SAS). PhyB is the main phytochrome controlling SAS. Interestingly, PhyB inactivation or mutation in Arabidopsis is accompanied by suppression of immune responses leading to enhanced susceptibility to insect damage and fungal infection. Given that PhyB controls the systemic differentiation of stomata and systemic development of the photosynthesis apparatus, we wondered if PhyB might also regulate the systemic induction of the defense response controlled by the phytohormone jasmonate (JA). To address this question we used a set of transgenic lines with tissue-specific expression of PhyB or inducible expression of PhyB. In order to establish the PhyB contribution to the systemic defense response, we performed bioassays based on the infectionof the necrotrophic fungi Botrytis cinerea and monitored total phenolic contents and the expression of marker genes in leaves. The results will be discussed in the context of the current knowledge of the field.