Capsicum chinense Jacq.-derived glutaredoxin (CcGRXS12) alters redox status of the cells to confer resistance against pepper mild mottle virus (PMMoV-I).

KEY MESSAGE: The CcGRXS12 gene protects plants from cellular oxidative damage that are caused by both biotic and abiotic stresses. The protein possesses GSH-disulphide oxidoreductase property but lacks Fe-S cluster assembly mechanism. Glutaredoxins (Grxs) are small, ubiquitous and multi-functional proteins. They are present in different compartments of plant cells. A chloroplast targeted Class I GRX (CcGRXS12) gene was isolated from Capsicum chinense during the pepper mild mottle virus (PMMoV) infection. Functional characterization of the gene was performed in Nicotiana benthamiana transgenic plants transformed with native C. chinense GRX (Nb:GRX), GRX-fused with GFP (Nb:GRX-GFP) and GRX-truncated for chloroplast sequences fused with GFP (Nb:Δ2MGRX-GFP). Overexpression of CcGRXS12 inhibited the PMMoV-I accumulation at the later stage of infection, accompanied with the activation of salicylic acid (SA) pathway pathogenesis-related (PR) transcripts and suppression of JA/ET pathway transcripts. Further, the reduced accumulation of auxin-induced Glutathione-S-Transferase (pCNT103) in CcGRXS12 overexpressing lines indicated that the protein could protect the plants from the oxidative stress caused by the virus. PMMoV-I infection increased the accumulation of pyridine nucleotides (PNs) mainly due to the reduced form of PNs (NAD(P)H), and it was high in Nb:GRX-GFP lines compared to other transgenic lines. Apart from biotic stress, CcGRXS12 protects the plants from abiotic stress conditions caused by H2O2 and herbicide paraquat. CcGRXS12 exhibited GSH-disulphide oxidoreductase activity in vitro; however, it was devoid of complementary Fe-S cluster assembly mechanism found in yeast. Overall, this study proves that CcGRXS12 plays a crucial role during biotic and abiotic stress in plants.

Over-expression of a grafting-responsive gene from hickory increases abiotic stress tolerance in Arabidopsis.

KEY MESSAGE: A grafting response gene CcPIP1;2 was cloned from hickory plant, further functional characterization of the gene for water transport activity and abiotic stress tolerances were carried out through heterologous expression in Xenopus and Arabidopsis. Plasma membrane intrinsic proteins (PIPs) are multifunctional channel proteins belonging to the membrane intrinsic protein (MIP) family. In this study, a grafting-responsive gene from hickory (CcPIP1;2) was cloned and functionally characterized. Application of non-selective water inhibitors (HgCl2 and phloretin) led to the death of grafted hickory plants at 30 days after grafting (DAG). Furthermore, the transcript accumulation of the selected CcPIP1;2 gene was gradually decreased from 0 to 14 DAG in the grafted samples under inhibitor treatment conditions. Transient expression analysis of the GFP-CcPIP1;2 fusion protein showed that CcPIP1;2 was located at plasma membrane. Heterologous expression of CcPIP1;2 protein in the Xenopus oocyte system helped the access of water into the cells. Over-expression of CcPIP1;2 in Arabidopsis improved the percentage of seed germination when the seeds were grown in H2O2-, ABA-, and mannitol-containing media, but had no effect when grown in the salt containing media. CcPIP1;2 transgenic plants grew better under drought conditions. The expression of various ABA-related stress marker genes as well as cell wall expansin marker genes was significantly higher in CcPIP1;2 over-expression Arabidopsis lines than in the wild type (WT).

Transcriptomic and metabolomic analyses reveal the importance of ethylene networks in mulberry fruit ripening.

Mulberry (Morus alba L.) is a climacteric and highly perishable fruit. Ethylene has been considered to be an important trigger of fruit ripening process. However, the role of ethylene in the mulberry fruit ripening process remains unclear. In this study, we performed a comprehensive analysis of metabolomic and transcriptomic data of mulberry fruit and the physiological changes accompanying the fruit ripening process. Our study revealed that changes in the accumulation of specific metabolites at different stages of fruit development and ripening were closely correlated to transcriptional changes as well as underlying physiological changes and the development of taste biomolecules. The ripening of mulberry fruits was highly associated with the production of endogenous ethylene, and further application of exogenous ethylene assisted the ripening process. Transcriptomic analysis revealed that differential expression of diverse ripening-related genes was involved in sugar metabolism, anthocyanin biosynthesis, and cell wall modification pathways. Network analysis of transcriptomics and metabolomics data revealed that many transcription factors and ripening-related genes were involved, among which ethylene-responsive transcription factor 3 (MaERF3) plays a crucial role in the ripening process. The role of MaERF3 in ripening was experimentally proven in a transient overexpression assay in apples. Our study indicates that ethylene plays a vital role in modulating mulberry fruit ripening. The results provide a basis for guiding the genetic manipulation of mulberry fruits towards sustainable agricultural practices and improve post-harvest management, potentially enhancing the quality and shelf life of mulberry fruits for sustainable agriculture and forestry.

Gut Enterobacteriaceae and uraemic toxins - Perpetrators for ageing.

Ageing is a complex process that is associated with changes in the composition and functions of gut microbiota. Reduction of gut commensals is the hallmarks of ageing, which favours the expansion of pathogens even in healthy centenarians. Interestingly, gut Enterobacteriaceae have been found to be increased with age and also consistently observed in the patients with metabolic diseases. Thus, they are associated with all-cause mortality, regardless of genetic origin, lifestyle, and fatality rate. Moreover, Enterobacteriaceae are also implicated in accelerating the ageing process through telomere attrition, cellular senescence, inflammasome activation and impairing the functions of mitochondria. However, acceleration of ageing is likely to be determined by intrinsic interactions between Enterobacteriaceae and other associated gut bacteria. Several studies suggested that Enterobacteriaceae possess genes for the synthesis of uraemic toxins. In addition to intestine, Enterobacteriaceae and their toxic metabolites have also been found in other organs, such as adipose tissue and liver and that are implicated in multiorgan dysfunction and age-related diseases. Therefore, targeting Enterobacteriaceae is a nuance approach for reducing inflammaging and enhancing the longevity of older people. This review is intended to highlight the current knowledge of Enterobacteriaceae-mediated acceleration of ageing process.