Protein subunit

Enzyme

Transcription factor

Biology

Gene

Abiotic component

Ecology

Paclobutrazol

Botany

Cell biology

Calmodulin

Genetics

Biochemistry

Locus (genetics)

Nature Plants

Global warming threatens crop production. G proteins mediate plant responses to multiple abiotic stresses. Here we identified a natural quantitative trait locus, TT2 (THERMOTOLERANCE 2), encoding a Gγ subunit, that confers thermotolerance in rice during both vegetative and reproductive growth without a yield penalty. A natural allele with loss of TT2 function was associated with greater retention of wax at high temperatures and increased thermotolerance. Mechanistically, we found that a transcription factor, SCT1 (Sensing Ca2+ Transcription factor 1), functions to decode Ca2+ through Ca2+-enhanced interaction with calmodulin and acts as a negative regulator of its target genes (for example, Wax Synthesis Regulatory 2 (OsWR2)). The calmodulin–SCT1 interaction was attenuated by reduced heat-triggered Ca2+ caused by disrupted TT2, thus explaining the observed heat-induced changes in wax content. Beyond establishing a bridge linking G protein, Ca2+ sensing and wax metabolism, our study illustrates innovative approaches for developing potentially yield-penalty-free thermotolerant crop varieties. TT2 is identified as a negative regulator of thermotolerance. It triggers Ca2+ signalling upon heat stress, which is then decoded by SCT1–CaM interaction. SCT1 reduces the transcription of its target OsWR2, thereby causing reduction in wax biosynthesis.

TT2 controls rice thermotolerance through SCT1-dependent alteration of wax biosynthesis