Genome-Wide Association Study Unravels as a Dark Respiration Regulator in Rice ( L.).

Respiration is a major plant physiological process that generates adenosine triphosphate (ATP) to support the various pathways involved in the plant growth and development. After decades of focused research on basic mechanisms of respiration, the processes and major proteins involved in respiration are well elucidated. However, much less is known about the natural variation of respiration. Here we conducted a survey on the natural variation of leaf dark respiration () in a global rice minicore diversity panel and applied a genome-wide association study (GWAS) in rice ( L.) to determine candidate loci associated with . This rice minicore diversity panel consists of 206 accessions, which were grown under both growth room (GR) and field conditions. We found that shows high single-nucleotide polymorphism (SNP) heritability under GR and it is significantly affected by genotype-environment interactions. also exhibits strong positive correlation to the leaf thickness and chlorophyll content. GWAS results of collected under GR and field show an overlapped genomic region in the chromosome 3 (Chr.3), which contains a lead SNP (3m29440628). There are 12 candidate genes within this region; among them, three genes show significantly higher expression levels in accessions with high . Particularly, we observed that the gene, annotated as leucine rich repeat receptor kinase, was up-regulated four times. We further found that a single significantly associated SNPs at the promoter region of , was strongly correlated with the mean annual temperature of the regions from where minicore accessions were collected. A rice mutant shows only ~37% of that of WT and retarded growth following exposure to 35 °C for 30 days, but only 24% reduction in growth was recorded under normal temperature (25 °C). This study demonstrates a substantial natural variation of in rice and that the gene can regulate leaf dark respiratory fluxes, especially under high temperature.