Ethephon Activates the Transcription of Senescence-Associated Genes and Nitrogen Mobilization in Grapevine Leaves (Vitis vinifera cv. Riesling)

Nitrogen (N) remobilization in the context of leaf senescence is of considerable importance for the viability of perennial plants. In late-ripening crops, such as Vitis vinifera, it may also affect berry ripening and fruit quality. Numerous studies on the model plant Arabidopsis thaliana have confirmed an involvement of the plant hormone ethylene in the regulation of senescence. However, ethylene research on grapevine was mostly focused on its involvement in berry ripening and stress tolerance until now. To investigate the effect of ethylene on the initiation, regulation, and progress of senescence-dependent N mobilization in grapevine leaves, we treated field-grown Vitis vinifera cv. Riesling vines with 25 mM ethephon at the end of berry ripening. Ethephon induced premature chlorophyll degradation and caused a shift of the leaf transcriptome equivalent to developmental leaf senescence. The upregulated metabolic processes covered the entire N remobilization process chain, altered the amino acid composition in the leaves, and resulted in an average 60% decrease in leaf N. Our findings increase the fundamental knowledge about the initiation and manipulation of leaf N remobilization in perennial woody plants by ethephon. This offers a methodological approach to the targeted induction of senescence and thus to an improvement in the N supply of grapes.

In silico identification and expression analysis of Metal-nicotianamine transporter (YSL3) and Oligopeptide transporter 3 (OPT3) under Cd stress in Brassica oleracea var. acephala

Background: Metal-nicotianamine transporter (YSL) family protein belongs to the oligopeptide heavy metal transporter group, as characterized in Arabidopsis thaliana. Oligopeptide transporters (OPTs) are a group of membrane-localized proteins, involved in different transport mechanisms, contributing to nitrogen mobilization, glutathione transport and long-distance metal distribution. Metal-nicotianamine transporter gene 3 (YSL3) incorporates the oligopeptide transporter domain, found to transfer several heavy metals in diverse plant species, and among them cadmium transport in Brassica oleracea. Objective: To evaluate and confirm the expression of Metal-nicotianamine transporter (YSL3) under cadmium stress. Studied species: Brassica oleracea var. acephala Study site and dates: Brassica oleracea var. acephala samples were collected from Blagaj region, Bosnia and Herzegovina. Methods: Through a simple bioinformatic approach the interactome partner of Metal-nicotianamine transporter (YSL3) was discovered and annotated. Oligopeptide transporter 3 (OPT3) and Metal-nicotianamine transporter (YSL3) genes were checked for expression levels under cadmium stress. Results: We have identified a strong interacting partner of YSL3, later confirmed as Oligopeptide transporter 3 (OPT3) protein in Brassica oleracea. The in vitro expression analysis by using a qRT-PCR revealed a significant upregulation of YSL3 and OPT3, during Cd stress. Conclusions: These findings indicate that the represented in-silico approach, followed by in vitro gene expression study, successfully confirmed YSL3 and identified OPT3 as a new gene, in correlation to cadmium stress.

Transcriptomic and Metabolomic Changes Triggered by Fusarium solani in Common Bean (Phaseolus vulgaris L.)

Common bean (Phaseolus vulgaris L.) is a major legume and is frequently attacked by fungal pathogens, including Fusarium solani f. sp. phaseoli (FSP), which cause Fusarium root rot. FSP substantially reduces common bean yields across the world, including China, but little is known about how common bean plants defend themselves against this fungal pathogen. In the current study, we combined next-generation RNA sequencing and metabolomics techniques to investigate the changes in gene expression and metabolomic processes in common bean infected with FSP. There were 29,722 differentially regulated genes and 300 differentially regulated metabolites between control and infected plants. The combined omics approach revealed that FSP is perceived by PAMP-triggered immunity and effector-triggered immunity. Infected seedlings showed that common bean responded by cell wall modification, ROS generation, and a synergistic hormone-driven defense response. Further analysis showed that FSP induced energy metabolism, nitrogen mobilization, accumulation of sugars, and arginine and proline metabolism. Importantly, metabolic pathways were most significantly enriched, which resulted in increased levels of metabolites that were involved in the plant defense response. A correspondence between the transcript pattern and metabolite profile was observed in the discussed pathways. The combined omics approach enhances our understanding of the less explored pathosystem and will provide clues for the development of common bean cultivars’ resistant to FSP.

Combined De Novo Transcriptome and Metabolome Analysis of Common Bean Response to Fusarium oxysporum f. sp. phaseoli Infection

Molecular changes elicited by common bean (Phaseolus vulgaris L.) in response to Fusarium oxysproum f. sp. Phaseoli (FOP) remain elusive. We studied the changes in root metabolism during common bean–FOP interactions using a combined de novo transcriptome and metabolome approach. Our results demonstrated alterations of transcript levels and metabolite concentrations in common bean roots 24 h post infection as compared to control. The transcriptome and metabolome responses in common bean roots revealed significant changes in structural defense i.e., cell-wall loosening and weakening characterized by hyper accumulation of cell-wall loosening and degradation related transcripts. The levels of pathogenesis related genes were significantly higher upon FOP inoculation. Interestingly, we found the involvement of glycosylphosphatidylinositol- anchored proteins (GPI-APs) in signal transduction in response to FOP infection. Our results confirmed that hormones have strong role in signaling pathways i.e., salicylic acid, jasmonate, and ethylene pathways. FOP induced energy metabolism and nitrogen mobilization in infected common bean roots as compared to control. Importantly, the flavonoid biosynthesis pathway was the most significantly enriched pathway in response to FOP infection as revealed by the combined transcriptome and metabolome analysis. Overall, the observed modulations in the transcriptome and metabolome flux as outcome of several orchestrated molecular events are determinant of host’s role in common bean–FOP interactions.