Abstract
Highlight Circadian clock robustness to high temperature is controlled by nuclear and plasmotype quantitative trait loci in wild barley (Hordeum vulgare ssp. spontaneum) reciprocal doubled haploid population
Abstract Temperature compensation, the ability to maintain the clock characteristics (mainly period) in face of temperature changes, is a considered a key feature of circadian clock systems. In this study, we explore the genetic basis for the circadian clock plasticity under high temperature by utilizing a new doubled haploid (DH) population derived from two reciprocal Hordeum vulgare sps. spontaneum hybrids genotypes (B1K-50-04 and B1K-09-07). Genotyping by sequencing of DH lines indicate a rich recombination landscape with minor fixation (less than 8%) for one of the parental allele, yet with prevalent and varied segregation distortion across seven barley chromosomes. Phenotyping this population was conducted with a high-throughput platform under optimal and high temperature environments. Genetic analysis by different ways, including QxE and binary-threshold models, identified significant influence of the maternal organelle genome (the plasmotype), as well as few nuclear quantitative trait loci (QTL), on clock phenotypes (free-running period and amplitude). Moreover, it showed a differential contribution of cytoplasmic genomes to buffering of the clock rhythm against high temperature. Resequencing of the parental chloroplast indicate the presence of few candidate genes underlying these significant effects. This first reported plasmotype-driven clock plasticity paves the way for identifying hitherto unknown role of nuclear and plasmotype variations on clock robustness and on plant adaptation to changing environments.