Dataset Information

The role of ABA in triggering ethylene biosynthesis and ripening of tomato fruit.

ABSTRACT: In order to understand more details about the role of abscisic acid (ABA) in fruit ripening and senescence of tomato, two cDNAs (LeNCED1 and LeNCED2) which encode 9-cis-epoxycarotenoid dioxygenase (NCED) as a key enzyme in ABA biosynthesis, two cDNAs (LeACS2 and LeACS4) which encode 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and one cDNA (LeACO1) which encodes ACC oxidase involved in ethylene biosynthesis were cloned from tomato fruit using a reverse transcription-PCR (RT-PCR) approach. The relationship between ABA and ethylene during ripening was also investigated. Among six sampling times in tomato fruits, the LeNCED1 gene was highly expressed only at the breaker stage when the ABA content becomes high. After this, the LeACS2, LeACS4, and LeACO1 genes were expressed with some delay. The change in pattern of ACO activity was in accordance with ethylene production reaching its peak at the pink stage. The maximum ABA content preceded ethylene production in both the seeds and the flesh. The peak value of ABA, ACC, and ACC oxidase activity, and ethylene production all started to increase earlier in seeds than in flesh tissues, although they occurred at different ripening stages. Exogenous ABA treatment increased the ABA content in both flesh and seed, inducing the expression of both ACS and ACO genes, and promoting ethylene synthesis and fruit ripening, while treatment with fluridone or nordihydroguaiaretic acid (NDGA) inhibited them, delaying fruit ripening and softening. Based on the results obtained in this study, it was concluded that LeNCED1 initiates ABA biosynthesis at the onset of fruit ripening, and might act as an original inducer, and ABA accumulation might play a key role in the regulation of ripeness and senescence of tomato fruit.

SUBMITTER: Zhang M

PROVIDER: S-EPMC2671613 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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The role of ABA in triggering ethylene biosynthesis and ripening of tomato fruit.

Zhang Mei M Yuan Bing B Leng Ping P

Journal of experimental botany 20090226 6

In order to understand more details about the role of abscisic acid (ABA) in fruit ripening and senescence of tomato, two cDNAs (LeNCED1 and LeNCED2) which encode 9-cis-epoxycarotenoid dioxygenase (NCED) as a key enzyme in ABA biosynthesis, two cDNAs (LeACS2 and LeACS4) which encode 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and one cDNA (LeACO1) which encodes ACC oxidase involved in ethylene biosynthesis were cloned from tomato fruit using a reverse transcription-PCR (RT-PCR) approac ...[more]

PMID: 19246595

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Project description:Light signaling and plant hormones, particularly ethylene and auxins, have been identified as important regulators of carotenoid biosynthesis during tomato fruit ripening. However, whether and how the light and hormonal signaling cascades crosstalk to control this metabolic route remain poorly elucidated. Here, the potential involvement of ethylene and auxins in the light-mediated regulation of tomato fruit carotenogenesis was investigated by comparing the impacts of light treatments and the light-hyperresponsive high pigment-2 (hp2) mutation on both carotenoid synthesis and hormonal signaling. Under either light or dark conditions, the overaccumulation of carotenoids in hp2 ripening fruits was associated with disturbed ethylene production, increased expression of genes encoding master regulators of ripening and higher ethylene sensitivity and signaling output. The increased ethylene sensitivity observed in hp2 fruits was associated with the differential expression of genes encoding ethylene receptors and downstream signaling transduction elements, including the downregulation of the transcription factor ETHYLENE RESPONSE FACTOR.E4, a repressor of carotenoid synthesis. Accordingly, treatments with exogenous ethylene promoted carotenoid biosynthetic genes more intensively in hp2 than in wild-type fruits. Moreover, the loss of HP2 function drastically altered auxin signaling in tomato fruits, resulting in higher activation of the auxin-responsive promoter DR5, severe down-regulation of AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) genes and altered accumulation of AUXIN RESPONSE FACTOR (ARF) transcripts. Both tomato ARF2 paralogues (Sl-ARF2a and SlARF2b) were up-regulated in hp2 fruits, which agrees with the promotive roles played by these ARFs in tomato fruit ripening and carotenoid biosynthesis. Among the genes differentially expressed in hp2 fruits, the additive effect of light treatment and loss of HP2 function was particularly evident for those encoding carotenoid biosynthetic enzymes, ethylene-related transcription factors, Aux/IAAs and ARFs. Altogether, the data uncover the involvement of ethylene and auxin as part of the light signaling cascades controlling tomato fruit metabolism and provide a new link between light signaling, plant hormone sensitivity and carotenoid metabolism in ripening fruits.

Project description:Purpose: The goals of this study was to provide genome-wide data to investigate the molecular mechanism of the interaction between ABA and ethylene during tomato fruit ripening Methods: Regarding the fruits sampled at the 9th day as a well-characterized stage, we used RNA-seq to conducted a comparative analysis of exogenous ABA and NDGA effects on all components involved in biosynthesis and signaling of ethylene and ABA.The identified crucial genes in response to ABA were further performed a ripening time-course analysis by RT-PCR. In addition, we also detected how ethylene affected ABA action at the onset of ripening by treating the fruits with 1-MCP immediately after ABA application. Results: Our study not only illustrated how ABA regulated itself at the transcription level, but also elucidated that ABA can facilitate ethylene production and response by regulating some crucial genes such as LeACS4, LeACO1 and LeETR6 etc. In addition, investigation on the fruits treated with 1-MCP immediately after ABA exposure revealed that ethylene might be essential for the induction of ABA biosynthesis and signaling at the onset of fruit ripening. Furthermore, some specific transcription factors (TFs) known as regulators of ethylene synthesis and sensibility (e.g. MADS-RIN, TAGL1, CNR and NOR etc.) were also observed to be ABA responsive, which implied that ABA influenced ethylene action possibly through the regulation of these TFs expression. Conclusions: Our data suggested that ABA may act as an upstream regulator to modulate ethylene synthesis and signal transduction, which consequently influenced the ripening process. This comprehensive survey not only demonstrated how ABA regulated itself at the molecular level, but also indicated that ABA had a positive impact on ethylene production and action by regulating key genes such as LeACS2, LeACS4, LeACO1 and LeETR6. Besides, our results also revealed that ethylene might be of great importance to induce ABA accumulation and response at the onset of ripening. Moreover, many ripening related TFs, such as MADS-RIN, TAGL1, CNR and NOR, were observed to be affected by ABA, implying that a TF-mediated manner may be involved in the interaction between ABA and ethylene. This study extends our understanding of the mechanism that how ABA-triggered tomato fruit ripening, and illustrates the complex mechanism of reciprocity between ABA and ethylene at the transcription level.

Dataset Information

The role of ABA in triggering ethylene biosynthesis and ripening of tomato fruit.

Publications

The role of ABA in triggering ethylene biosynthesis and ripening of tomato fruit.

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