Supplemental Red light to cope with salt stress in pepper (Capsicum annuum L.) plants

Abstract

The use of complementary light spectra is a potential new approach to studying theincrease in plant resilience under stress conditions. In this work, the effect of R LED onthe plant response to salinity was studied. For that, pepper plants were treated with 50mM NaCl, during 2 weeks, with and without previous R LED pulse (GH CSSRM5.24OSLON ® Square model). Thus, the studied treatments were CON, R LED NaCl andLED+NaCl. Plant growth, antioxidant capacity of the plants, stomata opening, gasexchanges parameters and the expression of different intrinsic membrane proteins,aquaporin (AQPs) isoforms involved in water and CO2 transport, were determined.LED+NaCl treated plants showed higher shoot biomass, stomata conductance,transpiration and photosynthesis rate with regard NaCl treated plants, alleviatingtoxicity symptoms of salt stress. This increase in biomass and photosynthesis can berelated to enhanced stomata opening and the higher expression of PIP1;2 isoformsin LED+NaCl treated plants with regard NaCl treated plants, since this isoformis involved in water and CO2 transport. In roots, PIP2;7 expression was lower inLED+NaCl treated plants compared to NaCl plants, according to the PIP downregulation that might limit water loss and create a hydraulic signal that may inducestomatal regulation. Total flavonoids and phenolic compounds involved in plantprotection against salt stress as well as antioxidant ABTS capacity were higher inLED+NaCl treated plants regarding NaCl plants. Therefore, R LED may alleviatesalinity damage in pepper plants through an improved water and CO2 uptake and antioxidant capacity.