Elevated ambient temperature has wide effects on plant growth and development. ELF3, a proposed thermosensor, negatively regulates protein activity of the growth-promoting factor PIF4, and such an inhibitory effect is subjected to attenuation at warm temperature. However, how ELF3 stability is regulated at warm temperature remains enigmatic. Here, we report the identification of XBAT31 as the E3 ligase that mediates ELF3 degradation in response to warm temperature in Arabidopsis. XBAT31 interacts with ELF3, ubiquitinates ELF3, and promotes ELF3 degradation via the 26S proteasome. Mutation of XBAT31 results in enhanced accumulation of ELF3 and reduced hypocotyl elongation at warm temperature. In contrast, overexpression of XBAT31 accelerates ELF3 degradation and promotes hypocotyl growth. Furthermore, XBAT31 interacts with the B-box protein BBX18, and the XBAT31-mediated ELF3 degradation is dependent on BBX18. Thus, our findings reveal that XBAT31-mediated destruction of ELF3 represents an additional regulatory layer of complexity in temperature signaling during plant thermomorphogenesis.

Summary: Global warming has profound impact on growth and development, and plants constantly adjust their internal circadian clock to cope with external environment. However, how clock‐associated genes fine‐tune thermoresponsive growth in plants is little understood. We found that loss‐of‐function mutation of REVEILLE5 (RVE5) reduces the expression of circadian gene EARLY FLOWERING 4 (ELF4) in Arabidopsis, and confers accelerated hypocotyl growth under warm‐temperature conditions. Both RVE5 and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) accumulate at warm temperatures and bind to the same EE cis‐element presented on ELF4 promoter, but the transcriptional repression activity of RVE5 is weaker than that of CCA1. The binding of CCA1 to ELF4 promoter is enhanced in the rve5‐2 mutant at warm temperatures, and overexpression of ELF4 in the rve5‐2 mutant background suppresses the rve5‐2 mutant phenotype at warm temperatures. Therefore, the transcriptional repressor RVE5 finetunes ELF4 expression via competing at a cis‐element with the stronger transcriptional repressor CCA1 at warm temperatures. Such a competition–attenuation mechanism provides a balancing system for modulating the level of ELF4 and thermoresponsive hypocotyl growth under warm‐temperature conditions.

Four rotor unmanned aerial vehicle (UAV) control of the bottom of society, this article is based on the cascade PID algorithm with the improved design and double closed-loop position controller and attitude controller, the outer ring of position and attitude controller adopts hyperbolic tangent function as the position loop, position controller of the PID as the inner ring speed ring, inner ring USES the intelligent PID control algorithm as angular velocity loop. In this paper, detailed steps of UAV modelling are given, and experiments are carried out on ROS, PX4 and Prometheus. In the experiments, the algorithm is verified and compared with traditional PID and cascade PID control algorithms. The experimental results show that the double closed-loop intelligent controller designed in this paper can ensure the flight stability of the quadrotor UAV and the accuracy of the trajectory tracking, and has a certain anti-interference ability.