Dataset Information

Interference with Clp protease impairs carotenoid accumulation during tomato fruit ripening.

ABSTRACT: Profound metabolic and structural changes are required for fleshy green fruits to ripen and become colorful and tasty. In tomato (Solanum lycopersicum), fruit ripening involves the differentiation of chromoplasts, specialized plastids that accumulate carotenoid pigments such as β-carotene (pro-vitamin A) and lycopene. Here, we explored the role of the plastidial Clp protease in chromoplast development and carotenoid accumulation. Ripening-specific silencing of one of the subunits of the Clp proteolytic complex resulted in β-carotene-enriched fruits that appeared orange instead of red when ripe. Clp-defective fruit displayed aberrant chromoplasts and up-regulated expression of nuclear genes encoding the tomato homologs of Orange (OR) and ClpB3 chaperones, most probably to deal with misfolded and aggregated proteins that could not be degraded by the Clp protease. ClpB3 and OR chaperones protect the carotenoid biosynthetic enzymes deoxyxylulose 5-phosphate synthase and phytoene synthase, respectively, from degradation, whereas OR chaperones additionally promote chromoplast differentiation by preventing the degradation of carotenoids such as β-carotene. We conclude that the Clp protease contributes to the differentiation of chloroplasts into chromoplasts during tomato fruit ripening, acting in co-ordination with specific chaperones that alleviate protein folding stress, promote enzyme stability and accumulation, and prevent carotenoid degradation.

SUBMITTER: D'Andrea L

PROVIDER: S-EPMC5888976 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

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.

Dataset Information

Interference with Clp protease impairs carotenoid accumulation during tomato fruit ripening.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets