Suppressing ABA uridine diphosphate glucosyltransferase (SlUGT75C1) alters fruit ripening and the stress response in tomato

Abstract

Abscisic acid (ABA) glucose conjugation mediated by uridine diphosphate glucosyltransferases (UGTs) is an important pathway in regulating ABA homeostasis. In the present study, we investigated three tomato SlUGTs that are highly expressed in fruit during ripening, and these SlUGTs were localized to the cytoplasm and cell nucleus. Among these three UGTs, SlUGT75C1 catalyzes the glucosylation of both ABA and IAA in vitro; SlUGT76E1 can only catalyze the conjugation of ABA; and SlUGT73C4 cannot glycosylate either ABA or IAA. Therefore, SlUGT75C1 was selected for further investigation. SlUGT75C1 RNA interference significantly up-regulated the expression level of SlCYP707A2, which encodes an ABA 8'-hydroxylase but did not affect the expression of SlNCED1, which encodes a key enzyme in ABA biosynthesis. Suppression of SlUGT75C1 significantly accelerated fruit ripening by enhancing ABA levels and promoting the early release of ethylene. SlUGT75C1-RNAi altered the expression of fruit ripening genes (genes involved in ethylene release and cell wall catabolism). SlUGT75C1-RNAi seeds showed delayed germination and root growth compared with wild-type as well as increased sensitivity to exogenous ABA. SlUGT75C1-RNAi plants were also more resistant to drought stress. These results demonstrated that SlUGT75C1 plays a crucial role in ABA-mediated fruit ripening, seed germination, and drought responses in tomato.

Manipulation of β‐carotene levels in tomato fruits results in increased ABA content and extended shelf life

“…In the second network, centred around ethylene (Figure S5B; Table S16B), strongly co‐regulated genes were involved in ethylene biosynthesis, sensing and signal transduction, but also key ripening regulators and genes involved in ABA signal transduction (Tables S15 and S16B). This is consistent with recent suggestions of substantial crosstalk between the networks controlling these hormones during ripening (Galpaz et al , ; Ji et al , ; Sun et al , ).…”

“…In the second network, centred around ethylene ( Figure S5B; Table S16B), strongly co-regulated genes were involved in ethylene biosynthesis, sensing and signal transduction, but also key ripening regulators and genes involved in ABA signal transduction (Tables S15 and S16B). This is consistent with recent suggestions of substantial crosstalk between the networks controlling these hormones during ripening (Galpaz et al, 2008;Ji et al, 2014;Sun et al, 2017). Abamine treatment of LCYb-overexpressing fruits reduces ABA accumulation, increases ethylene production and reverses the long shelf life phenotype Abamine is a well-known inhibitor of NCED enzymatic action and of ABA biosynthesis (Han et al, 2004).…”

“…Knockout mutations of ZEAXANTHIN EPOXIDASE ( ZEP ) or silencing of 9‐cis‐EPOXYCAROTENOID DIOXYGENASE ( NCED ) results in decreased endogenous ABA and increased ethylene (Galpaz et al , ; Ji et al , ), respectively. In contrast, silencing of three CYP707A2 isoforms, encoding ABA 8′‐hydroxylases acting in ABA catabolism, or of ABA uridine diphosphate glucosyltransferase ( SlUGT75C1 ), which produces esterified ABA‐glucose, generated over‐ripe fruits with increased ABA levels (Ji et al , ; Sun et al , ). A similar phenotype was observed in RNAi lines for SlPP2C1 , a group A type 2C protein phosphatase involved in ABA signalling (Zhang et al , ).…”

Transcriptome Analysis Reveals Potential Roles of Abscisic Acid and Polyphenols in Adaptation of Onobrychis viciifolia to Extreme Environmental Conditions in the Qinghai-Tibetan Plateau

“…Uridine diphosphate glucosyltransferases (UGTs) are extensively believed to modulate the endogenous phytohormone homeostasis to further promote abiotic stress resistance in plants via their glycosylated function that is referred to the formation of hormone conjugates [ 93 , 94 , 95 , 96 , 97 , 98 ]. As expected, numerous DEGs encoding UGTs were identified to participate in various hormone-related pathways ( Figure 8 and Supplementary Table S7 ).…”

Natural variation in cytokinin maintenance improves salt tolerance in apple rootstocks

“…To obtain transgenic tomato lines, the recombinant plasmid was introduced into A. tumefaciens LBA4404 and transformed into cultivar Micro‐Tom following published methods (Sun et al, ). Ten‐day‐old cotyledon seedlings were used when the first true leaves were 2–3 mm long.…”