Jiangsu Normal University

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) has shown a high incidence rate in rice fields in recent years. Rice resistance breeding is considered as the most effective method for achieving economical and sustainable management of BLB disease. The essential basis for resistance breeding is rooted in the exploration of rice resistance genes and the clarification of the molecular mechanisms that underlie Xoo resistance. In our previous research, we showed that Xanthomonas outer protein XopZ and rice oxysterol-binding related protein ORP1C collaboratively regulate the compatible interaction between Xoo strain PXO99 and Nipponbare rice, but the deeper regulatory mechanisms remain unknown. In this study, we successfully constructed ORP1C overexpression rice using the plant binary expression vector pCAMBIA1301. Through a series of virulence and effector translocation detections in Xoo-rice interactions, we revealed that overexpression of the ORP1C gene largely increases rice resistance to multiple Xoo strains from different countries and regions. Mechanistically, ORP1C plays a Xoo resistant role through negatively regulating transcription activator-like effectors (TALEs) translocation, ORP1C has become a potential candidate gene resource for disease-resistant breeding in rice. Further studies also indicated that XopZ and ORP1C collaboratively regulate the compatible interaction of PXO99-Nipponbare by modulating TALEs translocation.

Resistance exercise leads to improved muscle function and metabolic homeostasis. Yet how circadian rhythm impacts exercise outcomes and its molecular transduction remains elusive.

Human volunteers were subjected to 4 weeks of resistance training protocols at different times of day to assess training outcomes and their associations with myokine irisin. Based on rhythmicity of Fibronectin type III domain containing 5 (FNDC5/irisin), we trained wild type and FNDC5 knockout mice at late active phase (high FNDC5/irisin level) or late rest phase (low FNDC5/irisin level) to analyze exercise benefits on muscle function and metabolic homeostasis. Molecular analysis was performed to understand the regulatory mechanisms of FNDC5 rhythmicity and downstream signaling transduction in skeletal muscle.

In this study, we showed that regular resistance exercises performed at different times of day resulted in distinct training outcomes in humans, including exercise benefits and altered plasma metabolomics. We found that muscle FNDC5/irisin levels exhibit rhythmicity. Consistent with human data, compared to late rest phase (low irisin level), mice trained chronically at late active phase (high irisin level) gained more muscle capacity along with improved metabolic fitness and metabolomics/lipidomics profiles under a high-fat diet, whereas these differences were lost in FNDC5 knockout mice. Mechanistically, Basic helix-loop-helix ARNT like 1 (BMAL1) and Peroxisome proliferative activated receptor, gamma, coactivator 1 alpha 4 (PGC1α4) induce FNDC5/irisin transcription and rhythmicity, and the signaling is transduced via αV integrin in muscle.

Together, our results offered novel insights that exercise performed at distinct times of day determines training outcomes and metabolic benefits through the rhythmic regulation of the BMAL1/PGC1α4-FNDC5/irisin axis.

Drought is the main environmental factor limiting global crop yield in various abiotic stresses. Improving drought resistence of sweetpotato is necessary to ensure food security in the future climate scenarios. In this study, for Yanshu25 (Yan25, drought-tolerant cultivar), the genes related to jasmonic acid (JA) biosynthesis were significantly up-regulated by drought with relative higer endogenous JA content, while for Xushu32 (Xu32, drought-sensitive cultivar), the genes related to abscisic acid (ABA) biosynthesis were up-regulated by drought with relative higer endogenous ABA content. The coordinated regulation between JA and ABA on drought tolerance of sweetpotato was further carried using JA and ABA biosynthesis inhibitors--nordihydroguaiaretic acid (NDGA) or fluridone (FLU). Application of FLU or NDGA to drought-treated sweetpotato plants led to lower photosynthetic parameters and the activities of superoxide dismutase and peroxidase, and higher cell membrane damage under drought stress (D). For Xu32, under drought stress, FLU induced endogenous JA accumulation with lower expression level of JA signal transduction gene IbJAZ7, while NDGA did not affect ABA accumulation. FLU + JA recovered drought tolerance, as indicated by a significant increase of ABA content from D-FLU treatment, speculating that exogenous JA could promote endogenous ABA production. NDGA + ABA restored drought tolerance, as indicated by a significant up-regulation of JA and ABA contend from D treatment, speculating that endogenous ABA could also promote JA production and weaken NDGA inhibition. These results were in accordance with the expression trends of genes related to biosynthesis and signal transduction of JA and ABA. For Yan25, NDGA treatment increased leaf endogenous ABA content, and FLU treatment did not affect leaf JA accumulation. However, FLU + JA restored drought tolerance with higer ABA content and expressions of ABA-related genes. These results suggested that drought-sensitive sweetpotato was more dependent on ABA regulation pathway, and drought-tolerant sweetpotato was more dependent on JA regulation pathway under drought stress. In addition, there were positive feedback mechanisms of JA and ABA in sweetpotato in response to drought stress. Moreover, the function of IbAOS in sweetpotato roots was investigated and the results showed that IbAOS might improve drought tolerance by regulating JA biosynthesis. These results provided key information for further study of its role in tuberous root differentiation.