Arabidopsis thaliana natural variation in temperature-modulated immunity uncovers transcription factor UNE12 as a thermoresponsive regulator

Temperature impacts plant immunity and growth but how temperature intersects with endogenous pathways remains unclear. Here we uncover variation between Arabidopsis thaliana natural accessions in response to two non-stress temperatures (22°C and 16°C) affecting accumulation of the thermoresponsive stress hormone salicylic acid (SA) and plant growth. Analysis of differentially responding A. thaliana accessions shows that pre-existing SA provides a benefit in limiting bacterial pathogen infection at both temperatures. Several A. thaliana genotypes display a capacity to mitigate negative effects of high SA on growth, indicating within-species plasticity in SA - growth tradeoffs. An association study of temperature x SA variation, followed by physiological and immunity phenotyping of mutant and over-expression lines, identifies the transcription factor unfertilized embryo sac 12 ( UNE12 ) as a temperature-responsive SA immunity regulator. Here we reveal previously untapped diversity in plant responses to temperature and a way forward in understanding the genetic architecture of plant adaptation to changing environments.