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l -Tryptophan (Trp) is a substrate for the biosynthesis of melatonin, and melatonin is a signal molecule that alters the secondary metabolite profile; whether Trp treatments promote the biosynthesis of melatonin to regulate aroma compounds in grape berries and wine remains unclear. Here, the content of melatonin was higher in Marselan grapes and wine than that in other grape cultivars. Marselan grapes were subjected to 30 different Trp treatments. The content of melatonin and aroma compounds in Marselan grapes was increased by several treatments. Increases in the content of volatiles were mainly driven by increases in aldehydes. Hexanal, the most abundant aldehyde compound, was the main contributor to increases in aldehydes following Trp treatment. The results of our study indicate that the root application of 250 mg/L l -tryptophan during the fruiting expansion stage and the spraying application of 50 mg/L l -tryptophan spray during the veraison stage were the optimal treatments because the content of melatonin and aroma compounds, as well as other basic quality parameters, were highest in Trp-treated grape berries and wine in these treatments. Overall, these two effective Trp treatments could be used to enhance the content of melatonin and aroma compounds in Marselan grapes, and this could increase the economic value of this cultivar. [ABSTRACT FROM AUTHOR]

Anthropogenic and extreme climate disasters cause ecological changes in natural rivers and lakes, increasing the risk of starvation in yellowcheek (Elopichthys bambusa). Therefore, the impact of starvation on the metabolism and wild population of yellowcheek should be explored. In this study, we used transcriptome sequencing technology to analyze the effects of short (8 d) and long-term (28 d) starvation on the liver transcriptome, growth, and serum indicators of yellowcheek. Our results showed that short-term starvation significantly reduced the visceral weight and viscera index of yellowcheek. Long-term starvation significantly reduced the body weight and Fulton's condition factor, and it maintained significant reductions in visceral weight and viscera index. These results indicate that glycogen is the preferred energy source, rather than muscle protein, under starvation. Short-term starvation limited N-glycan and fatty acid biosynthesis, fatty acid elongation in the endoplasmic reticulum in the liver, and upregulated fatty acid degradation. However, long-term starvation alleviated the reduction in N-glycan and fatty acid biosynthesis caused by early starvation, and it significantly reduced fatty acid elongation in the mitochondria, as well as fatty acid degradation. These results provide important experiment information for assessing the starvation levels and nutritional status of wild yellowcheek. [ABSTRACT FROM AUTHOR]

Background: Organic acid secretion is a widespread physiological response of plants to alkalinity. However, the characteristics and underlying mechanism of the alkali-induced secretion of organic acids are poorly understood. Results: Oxalate was the main organic acid synthesized and secreted in grapevine (a hybrid of Vitis amurensis, V. berlandieri and V. riparia) roots, while acetate synthesis and malate secretion were also promoted under NaHCO3 stress. NaHCO3 stress enhanced the H+ efflux rate of grapevine roots, which is related to the plasma membrane H+-ATPase activity. Transcriptomic profiling revealed that carbohydrate metabolism was the most significantly altered biological process under NaHCO3 stress; a total of seven genes related to organic acid metabolism were significantly altered, including two phosphoenolpyruvate carboxylases and phosphoenolpyruvate carboxylase kinases. Additionally, the expression levels of five ATP-binding cassette transporters, particularly ATP-binding cassette B19, and two Al-activated malate transporter 2 s were substantially upregulated by NaHCO3 stress. Phosphoproteomic profiling demonstrated that the altered phosphoproteins were primarily related to binding, catalytic activity and transporter activity in the context of their molecular functions. The phosphorylation levels of phosphoenolpyruvate carboxylase 3, two plasma membrane H+-ATPases 4 and ATP-binding cassette B19 and pleiotropic drug resistance 12 were significantly increased. Additionally, the inhibition of ethylene synthesis and perception completely blocked NaHCO3-induced organic acid secretion, while the inhibition of indoleacetic acid synthesis reduced NaHCO3-induced organic acid secretion. Conclusions: Our results demonstrated that oxalate was the main organic acid produced under alkali stress and revealed the necessity of ethylene in mediating organic acid secretion. Additionally, we further identified several candidate genes and phosphoproteins responsible for organic acid metabolism and secretion. [ABSTRACT FROM AUTHOR]

• Improving the annotation file to identify more alternative splicing (AS) events. • A total of 1,466 AS events responded to salt stress in grapevine roots. • Salt-responsive AS events affect protein products and miRNA binding. • Salt-induced spliceosomal proteins were identified. • An innovative pipeline to discover the interactions between AS and alternative polyadenylation. Alternative splicing (AS) can enhance the adaptive capacity of organisms to respond to abiotic stresses via transcriptome plasticity; however, the mechanism underlying the responses of AS events to salt remains unclear in grapevine roots. In this study, an optimized genome annotation file was generated using Iso-Seq and RNA-seq data of grapevine roots. Based on the updated file, a total of 8,453 AS events across five types were identified in A17 grapevine roots, of which retained intron (RI) was the most dominant type. A total of 1,466 AS events affiliated with 1,113 genes responded to salt stress in grapevine roots. A global decrease in the proportion of inclusion isoforms was demonstrated, indicating that salt stress promoted the production of shorter isoforms. Only 206 salt-responsive AS events were affiliated with differentially expressed genes, indicating little overlap between transcriptional regulation and post-transcriptional regulation. A total of 672 and 410 AS events affected the length of protein products and miRNA binding, respectively. Differentially spliced genes were primarily related to RNA processing, nucleic acid binding, and ion channel activity. In addition, the salt-induced spliceosomal protein genes LSM2 and SRSF1 were identified, and their possible roles in regulating AS events were inferred. Moreover, we drafted an approach to explore possible interactions between AS and alternative polyadenylation (APA) using Iso-Seq data. Overall, these findings provide a comprehensive understanding of salt-responsive AS events in grapevine roots, providing insight into the molecular mechanism of salt tolerance in grapevine. [ABSTRACT FROM AUTHOR]

• Accumulation of organic acids in grapevine roots under NaHCO3 stress. • Analysis of signal transduction caused by acetic acid via split-root grapevines. • Acetic acid enhances NaHCO3 tolerance via salicylic acid. To demonstrate the role of acetic acid in increasing the tolerance of grapevines to NaHCO3 and reveal the underlying mechanism, the alkali-tolerant rootstock AB11, planted in a split-root system, was used in this study. The content of acetic acid was largely increased in the NaHCO3-treated half and nontreated half of split-root grapevines. When 25 mM acetic acid was applied to half the roots and the other half was treated with NaHCO3, acetic acid decreased the injury of the NaHCO3-treated roots and increased the grapevine tolerance to NaHCO3. Both acetic acid and NaHCO3 treatments largely increased the content of salicylic acid (SA) in roots, and additionally, the two treatments generated additive effects on SA accumulation. The application of the SA biosynthesis inhibitor 1-aminobenzotriazole decreased the grapevine tolerance to NaHCO3 induced by acetic acid. Taken together, the synthesis of acetic acid was induced by NaHCO3, and acetic acid treatment enhanced grapevine tolerance to NaHCO3 via SA. [ABSTRACT FROM AUTHOR]

Gene expression profile, phenolic composition, and antioxidant capacity were evaluated in red-fleshed berries and their wines (RF berries and wines) from new grape genotypes. Transcriptomic analysis revealed that ten metabolic pathways involved in polyphenol synthesis and catabolism were significantly altered, and 13 genes related to the biosynthesis and transport of phenolics were largely upregulated in RF berries compared to that of Cabernet Sauvignon (CS). Expression of MybA1 was associated with anthocyanin accumulation in red flesh. Additionally, RF berries and wines contained higher concentrations of total anthocyanins, phenols, flavonoids, and proanthocyanidins than those in CS berries and wine. Particularly, diglucosides of malvidin, peonidin, delphinidin, and cyanidin were present in red flesh and RF wines, but they were undetectable or present at very low concentrations in CS flesh and wine. Cinnamic acid and ferulic acid were clearly increased in the RF wines compared to those in the CS wine. Additionally, the RF wines had higher antioxidant capacity than that in the CS wine, and total anthocyanin content was significantly correlated to antioxidant capacity. This research provides insight into the mechanisms underlying grape flesh coloration and the composition of phenolic compounds in RF berries and wines.