EARLY MATURITY 7modifies the circadian clock and photoperiod sensitivity in barley

Abstract

AbstractBreeding for variation in photoperiod response is crucial to adapt crop plants to novel environments. Plants measure changes in day length by the circadian clock, an endogenous timekeeper that allows plants to anticipate changes in diurnal and seasonal light-dark cycles. Here, we describe theearly maturity 7(eam7) mutation in barley, which interacts with natural variation atPHOTOPERIOD 1(Ppd-H1) to cause early flowering independent of the photoperiod. We identifyLIGHT-REGULATED WD 1 (LWD1)as a putative candidate to underly theeam7locus in barley as supported by genetic mapping and CRISPR-Cas9 generatedlwd1mutants. Mutations ineam7cause a significant phase advance and a misregulation of core clock and clock output genes under diurnal conditions. Early flowering correlated with an upregulation ofPpd-H1during the night and consequent induction of the florigenFLOWERING LOCUS T1under short days. We propose thatEAM7controls photoperiodic flowering in barley by controlling the light input into the clock and diurnal expression patterns of the major photoperiod response genePpd-H1.