Abstract
Auxin has been shown to modulate the fruit ripening process. However, the molecular mechanisms underlying auxin regulation of fruit ripening are still not clear. Illumina RNA sequencing was performed on mature green cherry tomato fruit 1 and 7 days after auxin treatment, with untreated fruit as a control. The results showed that exogenous auxin maintained system 1 ethylene synthesis and delayed the onset of system 2 ethylene synthesis and the ripening process. At the molecular level, genes associated with stress resistance were significantly up-regulated, but genes related to carotenoid metabolism, cell degradation and energy metabolism were strongly down-regulated by exogenous auxin. Furthermore, genes encoding DNA demethylases were inhibited by auxin, whereas genes encoding cytosine-5 DNA methyltransferases were induced, which contributed to the maintenance of high methylation levels in the nucleus and thus inhibited the ripening process. Additionally, exogenous auxin altered the expression patterns of ethylene and auxin signaling-related genes that were induced or repressed in the normal ripening process, suggesting significant crosstalk between these two hormones during tomato ripening. The present work is the first comprehensive transcriptome analysis of auxin-treated tomato fruit during ripening. Our results provide comprehensive insights into the effects of auxin on the tomato ripening process and the mechanism of crosstalk between auxin and ethylene.
Highlights
Fruit ripening is a complex and highly coordinated process, which includes rapid changes in color, texture and flavor
Three crucial ripening-related TF genes, RIN (Solyc05g012020), CNR (Solyc02g077920) and TAGL1 (Solyc07g055920), were all repressed by auxin (RIN, log2 ratio: -2.89; CNR, log2 ratio: -2.16; TAGL1, log2 ratio: -0.64) (S4 Table). These findings suggest that auxin may regulate the expression of ripening-related TF genes, leading to changes in carotenoid biosynthesis, cell wall degradation and energy metabolism, delaying the ripening process
Auxin treatment up-regulated the expression of auxin response genes, glutathione S-transferases (GSTs)-encoding genes and stress tolerance-related TF genes and induced the recruitment of a large number of defense-associated genes to improve stress resistance and maintain auxin homeostasis
Summary
Fruit ripening is a complex and highly coordinated process, which includes rapid changes in color, texture and flavor. Ethylene and auxin are two important classes of phytohormones that have been reported to modulate fruit ripening [1,2,3]. Ethylene is the most important phytohormone in the climacteric fruit ripening process, and its function has been well documented [4,5,6]. Recent reports have indicated that the interaction between ethylene and auxin may be crucial for fruit ripening [7,8,9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
