CCA1 is a regulator of ABA-mediated abiotic stress tolerance in rice (Plant Physiol)

In rice, the circadian clock component gene Circadian Clock Associated 1 (OsCCA1) regulates flowering and nitrogen use efficiency. CCA1 is a MYB family transcription factor that follows a rhythmic expression pattern. Wei et al. confirmed the role of CCA1as a key hub in coordinating plant growth and abiotic stress adaptation. Transcript abundance of OsCCA1 was repressed by salt and drought stresses. Among the 692 target genes bound by CCA1 identified in DNA-affinity purification (DAP)-seq library, components of ABA signaling including clade A PP2cs and bZIP46 were particularly enriched. It was also confirmed that OsCCA1 could bind to the promoter regions of OsPP108 and bZIP46 and activate their expression. The Oscca1 mutants were short in stature and hypersensitive to salt and osmotic stresses, with reduced survival and reduced yield. Oscca1 mutants were also hypersensitive to ABA and showed comparatively lower survival than wild type after two weeks of ABA treatment. Thus, it is clear that under stress conditions OsCCA1 negatively modulates ABA signaling and by promoting the expression of negative regulators. The superior alleles or haplotypes of CCA1 and other circadian clock components are important targets for multiple stress tolerance in crop plants.  (Summary by Lekshmy Sathee @lekshmysnair) Plant Physiol. 10.1093/plphys/kiac196