The Arabidopsis UDP‐glycosyltransferases UGT79B2 and UGT79B3, contribute to cold, salt and drought stress tolerance via modulating anthocyanin accumulation

Abstract

These authors contributed equally to this work. SUMMARYThe plant family 1 UDP-glycosyltransferases (UGTs) are the biggest GT family in plants, which are responsible for transferring sugar moieties onto a variety of small molecules, and control many metabolic processes; however, their physiological significance in planta is largely unknown. Here, we revealed that two Arabidopsis glycosyltransferase genes, UGT79B2 and UGT79B3, could be strongly induced by various abiotic stresses, including cold, salt and drought stresses. Overexpression of UGT79B2/B3 significantly enhanced plant tolerance to low temperatures as well as drought and salt stresses, whereas the ugt79b2/b3 double mutants generated by RNAi (RNA interference) and CRISPR-Cas9 strategies were more susceptible to adverse conditions. Interestingly, the expression of UGT79B2 and UGT79B3 is directly controlled by CBF1 (CRT/DRE-binding factor 1, also named DREB1B) in response to low temperatures. Furthermore, we identified the enzyme activities of UGT79B2/B3 in adding UDP-rhamnose to cyanidin and cyanidin 3-O-glucoside. Ectopic expression of UGT79B2/B3 significantly increased the anthocyanin accumulation, and enhanced the antioxidant activity in coping with abiotic stresses, whereas the ugt79b2/b3 double mutants showed reduced anthocyanin levels. When overexpressing UGT79B2/B3 in tt18 (transparent testa 18), a mutant that cannot synthesize anthocyanins, both genes fail to improve plant adaptation to stress. Taken together, we demonstrate that UGT79B2 and UGT79B3, identified as anthocyanin rhamnosyltransferases, are regulated by CBF1 and confer abiotic stress tolerance via modulating anthocyanin accumulation.

An atypical R2R3 MYB transcription factor increases cold hardiness by CBF‐dependent and CBF‐independent pathways in apple

“…The cold induction of CBF genes by MdMYB88 and MdMYB124 prompted us to investigate their roles in anthocyanin accumulation, because CBF1 was shown to positively regulate anthocyanin accumulation (Li et al ., ). To test this, we examined anthocyanin accumulation in leaves of the transgenic plants after cold treatment.…”

“…Anthocyanins could protect plants from abiotic stresses including low temperature by serving as antioxidants (Li et al ., ). We tested H 2 O 2 accumulation of the WT, and MdMYB88 and MdMYB124 transgenic plants under cold stress.…”

“…Numerous studies have shown that cold‐induced anthocyanin biosynthesis is required for reactive oxygen species (ROS) scavenging and cold acclimation (Havaux & Kloppstech, ). For example, the anthocyanin biosynthesis genes UGT79B2 and UGT79B3 were shown to positively regulate anthocyanin production and ROS scavenging under cold (Li et al ., ). pfd mutant plants are more tolerant to low temperature by accumulating more anthocyanin after cold acclimation (Perea‐Resa et al ., ).…”

“…UGT79B2 and UGT79B3, responsible for overproduction of anthocyanin, also were found to be directly regulated by C‐REPEAT BINDING FACTOR (CBF)1 and play critical roles in plant cold tolerance (Li et al ., ). Ectopic expression of PpCBF1 in M26, a rootstock of apple, accumulated more anthocyanin in major and minor veins in transgenic lines after cold acclimation (Wisniewski et al ., ).…”

“…Anthocyanins, a main class of flavonoids, serve as protectants against biotic and abiotic stress, in addition to their roles in plant ecology and development (Van den Ende & El‐Esawe, ). Two Arabidopsis glycosyltransferases, UGT79B2 and UGT79B3, responsible for production of anthocyanin, are directly regulated by CBF1 and play critical roles in plant cold tolerance (Li et al ., ).…”