The Vitis yeshanensis U-box E3 ubiquitin ligase VyPUB21 enhances resistance to powdery mildew by targeting degradation of NIM1-interacting (NIMIN) protein.

KEY MESSAGE: VyPUB21 plays a key role during the defense against powdery mildew in grapes. Ubiquitin-ligating enzyme (E3), a type of protein widely found in plants, plays a key role in their resistance to disease. Yet how E3 participates in the disease-resistant response of Chinese wild grapevine (Vitis yeshanensis) remains unclear. Here we isolated and identified a U-box type E3 ubiquitin ligase, VyPUB21, from V. yeshanensis. This gene's expression level rose rapidly after induction by exogenous salicylic acid (SA), jasmonic acid (JA), and ethylene (ETH) and powdery mildew. In vitro ubiquitination assay results revealed VyPUB21 could produce ubiquitination bands after co-incubation with ubiquitin, ubiquitin-activating enzyme (E1), and ubiquitin-conjugating enzyme (E2); further, mutation of the conserved amino acid site in the U-box can inhibit the ubiquitination. Transgenic VyPUB21 Arabidopsis had low susceptibility to powdery mildew, and significantly fewer conidiophores and spores on its leaves. Expression levels of disease resistance-related genes were also augmented in transgenic Arabidopsis, and its SA concentration also significantly increased. VyPUB21 interacts with VyNIMIN and targets VyNIMIN protein hydrolysis through the 26S proteasome system. Thus, the repressive effect of the NIMIN-NPR complex on the late systemic acquired resistance (SAR) gene was attenuated, resulting in enhanced resistance to powdery mildew. These results indicate that VyPUB21 encoding ubiquitin ligase U-box E3 activates the SA signaling pathway, and VyPUB21 promotes the expression of late SAR gene by degrading the important protein VyNIMIN of SA signaling pathway, thus enhancing grape resistance to powdery mildew.

Transcription factor VviWOX13C regulates fruit set by directly activating VviEXPA37/38/39 in grape (Vitis vinifera L).

KEY MESSAGE: VviWOX13C plays a key regulatory role in the expansin during fruit set. Expansins as a type of non-enzymatic cell wall proteins, are responsible for the loosening and extension in cell walls leading to the enlargement of the plant cells. However, the current studies are still lacking in expansin genes associated with promoting fruit set. Here, 29 members of the expansin gene family were identified in the whole genome of grapes (Vitis vinifera L.), and the functional prediction of expansins was based on the gene annotated information. Results showed that the 29 members of grape expansin gene family could be mainly divided into four subfamilies (EXPA, EXPB, LIKE A, and LIKE B), distributed on 16 chromosomes. Replication analysis showed that there were four segmental duplications and two tandem duplications. Each expansins sequence contained two conserved domain features of grape EXPs (DPBB_1 and Expansin_C) through protein sequence analysis. The transcriptome sequencing results revealed that VviEXPA37, VviEXPA38, and VviEXPA39 were induced and upregulated by CPPU. Furthermore, transcriptional regulatory prediction network indicated that VviWOX13C targeted regulates VviEXPA37, VviEXPA38, and VviEXPA39 simultaneously. EMSA and dual luciferase assays demonstrated that VviWOX13C directly activated the expression of VviEXPA37, VviEXPA38, and VviEXPA39 by directly binding to its promoter. These results provide a basis for further studies on the function and regulatory mechanisms of expansin genes in fruit set.

First-principles study on the catalytic performance of transition metal atom-doped CrSe2 for the oxygen reduction reaction.

Since the oxygen reduction reaction (ORR) is the cathodic reaction of energy storage and conversion devices such as fuel cells and metal-air batteries, the search for catalysts with high-performance toward ORR has become the focus of attention. Transition metal dichalcogenides (TMDs) have the advantages of easy integration, inexpensive, harmless, good stability, and have vast application prospects in stabilizing the single atom. Hence, in this study, we investigated the feasibility of several 4d/5d single transition metals (TM = Rh, Pd, Ag, Ir, Pt, and Au) doped with CrSe2 for ORR electrocatalysis on the basis of density functional theory (DFT) calculations. Our results demonstrated that most of the TM-doped systems are stable, exhibiting metal conductivity, and can well activate the adsorbed O2. Interestingly, compared with end-on adsorption configuration, O2 is more likely to be adsorbed on the catalysts by a side-on adsorption configuration. Among all the candidate ORR catalysts, Pd-doped and Pt-doped CrSe2 have the best catalytic performance with a low overpotential of 0.43 and 0.50 V, respectively, making them good ORR candidate high performance catalysts. Our DFT work helps to understand the interaction between the O2 molecule and transition metal single atoms on CrSe2 supports and provides ideas for designing stable and efficient ORR catalysts.