Cold exposure transiently increases resistance ofArabidopsis thalianaagainst the fungal pathogenBotrytis cinerea

Abstract

ABSTRACTA sudden cold exposure (4°C, 24 h) primes resistance ofArabidopsis thalianaagainst the virulent biotrophic pathogenPseudomonas syringaepv.tomatoDC3000 (Pst) for several days. This effect is mediated by chloroplast cold sensing and the activity of stromal and thylakoid-bound ascorbate peroxidases (sAPX/tAPX). In this study, we investigated the impact of such cold exposure on plant defence against the necrotrophic fungusBotrytis cinerea. Plant resistance was transiently enhanced if theB. cinereainfection occurred immediately after the cold exposure, but this cold-enhancedB. cinerearesistance was absent when the cold treatment and the infection were separated by 5 days at normal growth conditions. Plastid ascorbate peroxidases partially contributed to the transient cold-enhanced resistance against the necrotrophic fungus. In response toB. cinerea, the levels of reactive oxygen species (ROS) were significantly higher in cold-pretreated Arabidopsis leaves. Pathogen-triggered ROS levels varied in the absence of sAPX, highlighting the strong capacity for sAPX-dependent ROS regulation in the chloroplast stroma. The cold-enhanced resistance againstB. cinereawas associated with cold-induced plant cell wall modifications, including sAPX-dependent callose formation and significant lignification in cold-treated Arabidopsis leaves.FundingThis work was supported by the German Research Foundation (CRC973/C4) and the FU Berlin.