两种富含甘氨酸的RNA结合蛋白参与选择性剪接实现对水稻耐热性的昼夜节律调控

Rice(Oryza sativa L.)production is threatened by global warming associated with extreme high temperatures,and rice heat sensitivity is differed when stress occurs between daytime and nighttime.However,the underlying molecular mechanism are largely unknown.We show here that two glycine-rich RNA binding proteins,Os GRP3 and Os GRP162,are required for thermotolerance in rice,especially at nighttime.The rhythmic expression of Os GRP3/Os GRP162 peaks at midnight,and at these coincident times,is increased by heat stress.This is largely dependent on the evening complex component Os ELF3-2.We next found that the double mutant of Os GRP3/Os GRP162 is strikingly more sensitive to heat stress in terms of survival rate and seed setting rate when comparing to the wild-type plants.Interestingly,the defect in thermotolerance is more evident when heat stress occurred in nighttime than that in daytime.Upon heat stress,the double mutant of Os GRP3/Os GRP162 displays globally reduced expression of heat-stress responsive genes,and increases of m RNA alternative splicing dominated by exon-skipping.This study thus reveals the important role of Os GRP3/Os GRP162 in thermotolerance in rice,and unravels the mechanism on how Os GRP3/Os GRP162 regulate thermotolerance in a diurnal manner.

The E3 ligase XBAT35 mediates thermoresponsive hypocotyl growth by targeting ELF3 for degradation in Arabidopsis

Plants are capable of coordination of their growth and development with ambient temperatures.EARLY FLOWERING3(ELF3), an essential component of the plant circadian clock, is also involved in ambient temperature sensing, as well as in inhibiting the expression and protein activity of the thermoresponsive regulator phytochrome interacting factor4(PIF4). The ELF3 activity is subjected to attenuation in response to warm temperature;however,how the protein level of ELF3 is regulated at warm temperature remains less understood. Here, we report that the E3 ligase XB3 ORTHOLOG 5 IN ARABIDOPSIS THALIANA, XBAT35, mediates ELF3 degradation. XBAT35 interacts with ELF3 and ubiquitinates ELF3. Loss-of-function mutation of XBAT35 increases the protein level of ELF3 and confers a short-hypocotyl phenotype under warm temperature conditions. Thus, our findings establish that XBAT35 mediates ELF3 degradation to lift the inhibition of ELF3 on PIF4 for promoting thermoresponsive hypocotyl growth in plants.

REVEILLE 7 inhibits the expression of the circadian clock gene EARLY FLOWERING 4 to fine-tune hypocotyl growth in response to warm temperatures

The circadian clock maintains the daily rhythms of plant growth and anticipates predictable ambient temperature cycles.The evening complex(EC),comprising EARLY FLOWERING 3(ELF3),ELF4,and LUX ARRHYTHMO,plays an essential role in suppressing thermoresponsive hypocotyl growth by negatively regulating PHYTOCHROME INTERACTING FACTOR 4(PIF4)activity and its downstream targets in Arabidopsis thaliana.However,how EC activity is attenuated by warm temperatures remains unclear.Here,we demonstrate that warm temperature-induced REVEILLE7(RVE7)fine-tunes thermoresponsive growth in Arabidopsis by repressing ELF4 expression.RVE7 transcript and RVE7 protein levels increased in response to warm temperatures.Under warm temperature conditions,an rve7 loss-of-function mutant had shorter hypocotyls,while overexpressing RVE7 promoted hypocotyl elongation.PIF4 accumulation and downstream transcriptional effects were reduced in the rve7 mutant but enhanced in RVE7 overexpression plants under warm conditions.RVE7 associates with the Evening Element in the ELF4 promoter and directly represses its transcription.ELF4 is epistatic to RVE7,and overexpressing ELF4 suppressed the phenotype of the RVE7 overexpression line under warm temperature conditions.Together,our results identify RVE7 as an important regulator of thermoresponsive growth that functions(in part)by controlling ELF4 transcription,highlighting the importance of ELF4 for thermomorphogenesis in plants.

Phytochrome-lnteracting Factors （PIFs） as Bridges between Environmental Signals and the Circadian Clock： Diurnal Regulation of Growth and Development

The rotation of the Earth around its axis results in distinct changes in light and temperature during a 24-h day/ night cycle. Plants being sessile are constantly and predictably exposed to these environmental changes. It is therefore critical for them to properly perceive environmental signals in order to effectively manage growth and development.

GIGANTEA Integrates Photoperiodic and Temperature Signals to Time when Growth Occurs

Circadian clocks synchronize internal physiological responses to occur at the most optimal time of the day.In plants,hormone signaling is under the control of this clock.It has been previously shown that the circadian clock moderates the plant’s sensitivity to gibberellin(GA)by regulating the expression of GA receptors.Recently,two papers by Nohales and Kay(2019)and Park et al.(2020)revealed that post-translational regulation of DELLA proteins by the circadian clock also contributes to timing when the plant is most sensitive to GA.