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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]