Search

Key message: Our results confirmed that SlERF.F5 can directly regulate the promoter activity of ACS6 and interact with SlMYC2 to regulate tomato leaf senescence. The process of plant senescence is complex and highly coordinated, and is regulated by many endogenous and environmental signals. Ethylene and jasmonic acid are well-known senescence inducers, but their molecular mechanisms for inducing leaf senescence have not been fully elucidated. Here, we isolated an ETHYLENE RESPONSE FACTOR F5 (SlERF.F5) from tomato. Silencing of SlERF.F5 causes accelerated senescence induced by age, darkness, ethylene, and jasmonic acid. However, overexpression of SlERF.F5 would not promote senescence. Moreover, SlERF.F5 can regulate the promoter activity of ACS6 in vitro and in vivo. Suppression of SlERF.F5 resulted in increased sensitivity to ethylene and jasmonic acid, decreased accumulation of chlorophyll content, and inhibited the expression of chlorophyll- and light response-related genes. Compared with the wild type, the qRT-PCR analysis showed the expression levels of genes related to the ethylene biosynthesis pathway and the jasmonic acid signaling pathway in SlERF.F5-RNAi lines increased. Yeast two-hybrid experiments showed that SlERF.F5 and SlMYC2 (a transcription factor downstream of the JA receptor) can interact physically, thereby mediating the role of SlERF.F5 in jasmonic acid-induced leaf senescence. Collectively, our research provides new insights into how ethylene and jasmonic acid promote leaf senescence in tomato. [ABSTRACT FROM AUTHOR]

MADS-box genes have been demonstrated to participate in a number of processes in tomato development, especially fruit ripening. In this study, we reported a novel MADS-box gene, SlMBP15, which is implicated in fruit ripening. Based on statistical analysis, the ripening time of SlMBP15-silenced tomato was delayed by 2–4 days compared with that of the wild-type (WT). The accumulation of carotenoids and biosynthesis of ethylene in fruits were decreased in SlMBP15-silenced tomato. Genes related to carotenoid and ethylene biosynthesis were greatly repressed. SlMBP15 can interact with RIN, a MADS-box regulator affecting the carotenoid accumulation and ethylene biosynthesis in tomato. In addition, SlMBP15-silenced tomato produced dark green leaves, and its plant height was reduced. The gibberellin (GA) content of transgenic plants was lower than that of the WT and GA biosynthesis genes were repressed. These results demonstrated that SlMBP15 not only positively regulated tomato fruit ripening but also affected the morphogenesis of the vegetative organs. [ABSTRACT FROM AUTHOR]

The tomato is a research model for fruit-ripening, however, its fruit-ripening mechanism still needs more extensive and in-depth exploration. Here, using TMT and LC-MS, the proteome and phosphoproteome of AC++ (wild type) and rin (ripening-inhibitor) mutant fruits were studied to investigate the translation and post-translational regulation mechanisms of tomato fruit-ripening. A total of 6141 proteins and 4011 phosphorylation sites contained quantitative information. One-hundred proteins were identified in both omics' profiles, which were mainly found in ethylene biosynthesis and signal transduction, photosynthesis regulation, carotenoid and flavonoid biosynthesis, chlorophyll degradation, ribosomal subunit expression changes, MAPK pathway, transcription factors and kinases. The affected protein levels were correlated with their corresponding gene transcript levels, such as NAC-NOR, MADS-RIN, IMA, TAGL1, MADS-MC and TDR4. Changes in the phosphorylation levels of NAC-NOR and IMA were involved in the regulation of tomato fruit-ripening. Although photosynthesis was inhibited, there were diverse primary and secondary metabolic pathways, such as glycolysis, fatty acid metabolism, vitamin metabolism and isoprenoid biosynthesis, regulated by phosphorylation. These data constitute a map of protein—protein phosphorylation in the regulation of tomato fruit-ripening, which lays the foundation for future in-depth study of the sophisticated molecular mechanisms of fruit-ripening and provide guidance for molecular breeding. [ABSTRACT FROM AUTHOR]

The acetylation levels of histones on lysine residues are regulated by histone acetyltransferases and histone deacetylases, which play an important but understudied role in the control of gene expression in plants. There is an increasing research focus on histone deacetylation in crops, but to date, there is little information regarding tomato. With the aim of characterizing the tomato HD2 family of histone deacetylases, an RNA interference (RNAi) expression vector of SlHDT3 was constructed and transformed into tomato plants. The time of fruit ripening was delayed and the shelf life of the fruit was prolonged in SlHDT3 RNAi lines. The accumulation of carotenoid was decreased by altering of the carotenoid pathway flux. Ethylene content was also reduced and expression of ethylene biosynthetic genes ( ACS2 , ACS4 and ACO1 , ACO3 ) and ripening-associated genes ( RIN , E4 , E8 , PG , Pti4 and LOXB ) was significantly down-regulated in SlHDT3 RNAi lines. The expression of genes involved in fruit cell wall metabolism ( HEX , MAN , TBG4 , XTH5 and XYL ) was inhibited compared with wild type. These results indicate that SlHDT3 functions as a positive regulator of fruit ripening by affecting ethylene synthesis and carotenoid accumulation and that SlHDT3 lies upstream of SlMADS-RIN in the fruit ripening regulatory network. [ABSTRACT FROM AUTHOR]