Heat-induced RING/U-BOX E3 ligase, TaUHS, is a negative regulator by facilitating TaLSD degradation during the grain filling period in wheat

Heat stress accelerates abnormal maturation and leads to numerous defects in wheat. Temperature determines the duration of plant growth and heat stress accelerates crop development, resulting in premature initiation of phenological stages. The grain filling period is sensitive and is easily exposed to heat stress, which reduces the grain weight and shortens the period. In this study, from anthesis through early spike maturity, we observed decreased grain weight and accelerated maturation under heat stress, resulting in poor grain development. Furthermore, the maturation of spikes was accelerated to shorten the grain filling and ripening periods under high temperatures. Triticum aestivum L. UBOX responding Heat Stress gene (TaUHS) (TraesCS1D02G145900, UBOX response heat stress) was highly expressed in grains located at the basal positions of the spike under high-temperature stress. TaUHS is an E3 ligase found in the nucleus and plasma membrane. We demonstrated that TaUHS interacts with Triticum aestivum L. LEA containing seed development gene (TaLSD) (TraesCS5A02G385600, LEA-containing seed development). TaLSD, which played stress resistance and desiccation tolerance at grain filling period, mediates ubiquitination and proteasomal degradation by 26S proteasome with TaUHS under high-temperature conditions. Proteolysis of TaLSD in conjugate with E3 ligase might occur to maintain cellular homeostasis and stability in response to unfavorable environmental conditions. Wheat RING/U-BOX E3 ligase negatively regulates late embryogenesis-abundant proteins during the grain filling period under heat stress.