Light‐ and temperature‐entrainable circadian clock in soybean development

Abstract

In plants, the spatiotemporal expression of circadian oscillators provides adaptive advantages in diverse species. However, the molecular basis of circadian clock in soybean is not known. In this study, we used soybean hairy roots expression system to monitor endogenous circadian rhythms and the sensitivity of circadian clock to environmental stimuli. We discovered in experiments with constant light and temperature conditions that the promoters of clock genes GmLCLb2 and GmPRR9b1 drive a self‐sustained, robust oscillation of about 24‐h in soybean hairy roots. Moreover, we demonstrate that circadian clock is entrainable by ambient light/dark or temperature cycles. Specifically, we show that light and cold temperature pulses can induce phase shifts of circadian rhythm, and we found that the magnitude and direction of phase responses depends on the specific time of these two zeitgeber stimuli. We obtained a quadruple mutant lacking the soybean gene GmLCLa1, LCLa2, LCLb1, and LCLb2 using CRISPR, and found that loss‐of‐function of these four GmLCL orthologs leads to an extreme short‐period circadian rhythm and late‐flowering phenotype in transgenic soybean. Our study establishes that the morning‐phased GmLCLs genes act constitutively to maintain circadian rhythmicity and demonstrates that their absence delays the transition from vegetative growth to reproductive development.

Diurnal metabolic regulation of isoflavones and soyasaponins in soybean roots

“…For each sample, color corresponds to the z-score given by the sample's TPM. ZT, hours after dawn.TPM, transcripts per million et al, 2013;Liew et al, 2017;Locke et al, 2018;Marcolino-Gomes et al, 2014;Wang et al, 2020) (Figure 2).…”

“…). The circadian clock-related transcription factors in soybeans include Late elongated hypocotyl/circadian clock associated (LCL), TOC1, PRR, GIGANTEA (GI), LUX ARRHYTHMO (LUX), and Early flowering 4 (ELF4)(Cheng et al, 2019;Li et al, 2013;Liew et al, 2017;Wang et al, 2020). The expression of these key circadian clock-related genes showed diurnal changes both in the leaves and roots and displayed a similar expression tendency as observed in previous studies(Cheng et al, 2019; Li F I G U R E 3 Phase sorted heatmap showing diurnally oscillating gene expressions in leaves (a) and roots (b).…”

The regulatory pathways of distinct flowering characteristics in Chinese jujube

“…In general, the circadian rhythm pathway is associated with the photoperiod pathway, and endogenous circadian rhythms are sensitive to light/dark stimuli 15,16 . The expression patterns of most genes involved in these two pathways showed sequential expression in this study (Fig.…”

GmLCLs negatively regulate ABA perception and signalling genes in soybean leaf dehydration response

“…As a facultative short‐day plant, soybeans exhibit unique photoperiod sensitivity and geographical adaptation (Lu et al, 2017; Lu et al, 2020; Wang, Sun, et al, 2020). Recent studies have shown that a large proportion of the soybean transcriptome is directly regulated by the circadian clock (Li et al, 2019; Li et al, 2020; Wang, Sun, et al, 2020). Our previous research found that the expression of LHY‐CCA1‐LIKE orthologs, GmLCLa1 , GmLCLa2 , GmLCLb1 and GmLCLb2 , showed a nearly 24‐hr rhythm under free‐running conditions, with a peak around dawn, and mutation of GmLCLs caused a shortened circadian period and late flowering phenotype (Wang, Yuan, et al, 2020).…”