Neighbour signals perceived by phytochrome B increase thermotolerance in Arabidopsis

ARICO DENISE; LEGRIS MARTINA; CASTRO LUCIANA; GARCIA, CARLOS FERNANDO; A LAINO; CASAL JORGE; MAZZELLA MARIA JOSE

PLANT, CELL AND ENVIRONMENT (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0140-7791

Due to the preeminence of reductionist approaches, understanding of plant responsesto combined stresses is limited.Wespeculated that light‐quality signals of neighbouringvegetation might increase susceptibility to heat shocks because shade reduces tissuetemperature and hence the likeness of heat shocks. In contrast, plants of Arabidopsisthaliana grown under low‐red/far‐red ratios typical of shade were less damaged by heatstress than plants grown under simulated sunlight. Neighbour signals reduce the activityof phytochrome B (phyB), increasing the abundance of PHYTOCHROMEINTERACTINGFACTORS (PIFs). The phyB mutant showed high tolerance to heat stresseven under simulated sunlight, and a pif multiple mutant showed low tolerance undersimulated shade. phyB and red/far‐red ratio had no effects on seedlings acclimatedwith nonstressful warm temperatures before the heat shock. The phyB mutant showedreduced expression of several fatty acid desaturase (FAD) genes and less proportion offully unsaturated fatty acids and electrolyte leakage of membranes exposed to heatshocks. Red‐light‐activated phyB also reduced thermotolerance of dark‐grown seedlingsbut not via changes in FADs expression and membrane stability. We propose thatthe reduced photosynthetic capacity linked to thermotolerant membranes would beless costly under shade, where the light input limits photosynthesis.