Rice Glycosyltransferase Gene UGT85E1 Is Involved in Drought Stress Tolerance Through Enhancing Abscisic Acid Response

Drought is one of the most important environmental constraints affecting plant growth and development and ultimately leads to yield loss. Uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs) are believed to play key roles in coping with environmental stresses. In rice, it is estimated that there are more than 200 UGT genes. However, most of them have not been identified as their physiological significance. In this study, we reported the characterization of a putative glycosyltransferase gene UGT85E1 in rice. UGT85E1 gene is significantly upregulated by drought stress and abscisic acid (ABA) treatment. The overexpression of UGT85E1 led to an enhanced tolerance in transgenic rice plants to drought stress, while the ugt85e1 mutants of rice showed a more sensitive phenotype to drought stress. Further studies indicated that UGT85E1 overexpression induced ABA accumulation, stomatal closure, enhanced reactive oxygen species (ROS) scavenging capacity, increased proline and sugar contents, and upregulated expression of stress-related genes under drought stress conditions. Moreover, when UGT85E1 was ectopically overexpressed in Arabidopsis, the transgenic plants showed increased tolerance to drought as well as in rice. Our findings suggest that UGT85E1 plays an important role in mediating plant response to drought and oxidative stresses. This work may provide a promising candidate gene for cultivating drought-tolerant crops both in dicots and monocots.

Molecular mechanism behind the involvement of apple flavonoid glycosyltransferase gene MdGT1 in the color of apple leaves

SummaryFlavonoids are a class of polyphenol compounds that are widespread in plants. They play an important role in plant growth and development. In this study, we found a mutant strain of M. baccata with yellow leaves (YL). Transcriptome sequencing revealed that it exhibited significant changes in the flavonoid metabolism pathway, which screening revealed was associated with a glycosyltransferase gene, MD09G1064900 (MdGT1). Analysis of its spatiotemporal expression showed that MdGT1 was mainly expressed in the stem and leaves, it means that MdGT1 may have a functional role in these parts. Real-time PCR and HPLC showed that MdGT1 was significantly upregulated by anthocyanin and exhibited strong anthocyaninase activity in vitro, respectively. An MdGT1 plant expression vector was constructed and overexpressed in apple fruit callus, resulting in a significant decrease of anthocyanin. Phenotypic observation also revealed that the MdGT1-overexpressing lines exhibited worse growth than the wild type after NaCl treatment, while they grew better upon the addition of exogenous anthocyanins. Moreover, real-time PCR and physiological data showed that MdGT1 is involved in salt stress and closely related to antioxidant pathways. Electrophoretic mobility shift assays (EMSA) and yeast one-hybrid experiments also proved that the transcription factor MdMYB88 is an upstream regulatory factor of MdGT1. The sequencing results revealed an amino acid insertion in an MdMYB88 HTH domain (between 77-131 amino acids) in the YL mutant strain. In conclusion, we identified a new apple glycosyltransferase gene, MdGT1, which may affect the color of apple leaves by glycosylating anthocyanins, and be regulated by the upstream transcription factor MdMYB88.Significance statementThe glycosyltransferases and their physiological significance in apple are largely unknown. Here we revealed that the MdMYB88-regulated apple glycosyltransferase gene MdGT1 plays a crucial role in the color of apple leaves and enhances plant tolerance to salt by antioxidant pathways via anthocyanin metabolism.

Comparative genomics of human Lactobacillus crispatus isolates reveals genes for glycosylation and glycogen degradation: Implications for in vivo dominance of the vaginal microbiota

Background: A vaginal microbiota dominated by lactobacilli (particularly Lactobacillus crispatus) is associated with vaginal health, whereas a vaginal microbiota not dominated by lactobacilli is considered dysbiotic. Here we investigated whether L. crispatus strains isolated from the vaginal tract of women with Lactobacillus-dominated vaginal microbiota (LVM) are pheno- or genotypically distinct from L. crispatus strains isolated from vaginal samples with dysbiotic vaginal microbiota (DVM). Results: We studied 33 L. crispatus strains (n=16 from LVM; n=17 from DVM). Comparison of these two groups of strains showed that, although strain differences existed, both groups were heterofermentative, produced similar amounts of organic acids, inhibited Neisseria gonorrhoeae growth and did not produce biofilms. Comparative genomics analyses of 28 strains (n=12 LVM; n=16 DVM) revealed a novel, 3-fragmented glycosyltransferase gene that was more prevalent among strains isolated from DVM. Most L. crispatus strains showed growth on glycogen-supplemented growth media. Strains that showed less efficient (n=6) or no (n=1) growth on glycogen all carried N-terminal deletions (respectively, 29 and 37 amino acid-deletions) in a putative pullulanase type I gene. Discussion: L. crispatus strains isolated from LVM were not phenotypically distinct from L. crispatus strains isolated from DVM, however, the finding that the latter were more likely to carry a 3-fragmented glycosyltransferase gene may indicate a role for cell surface glycoconjugates, which may shape vaginal microbiota-host interactions. Furthermore, the observation that variation in the pullulanase type I gene associated with growth on glycogen discourages previous claims that L. crispatus cannot directly utilize glycogen.