Comparative analysis of carotenoid accumulation in two goji Lycium barbarum L. and L. ruthenicumMurr. fruitsReport as inadecuate




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BMC Plant Biology

, 14:269

Biochemistry and physiology

Abstract

BackgroundThe traditional Chinese medicinal plants Lycium barbarum L. and L. ruthenicum Murr. are valued for the abundance of bioactive carotenoids and anthocyanins in their fruits, respectively. However, the cellular and molecular mechanisms contributing to their species-specific bioactive profiles remain poorly understood.

ResultsIn this study, the red fruit RF of L. barbarum was found to accumulate high levels of carotenoids primarily zeaxanthin, while they were undetectable in the black fruit BF of L. ruthenicum. Cytological and gene transcriptional analyses revealed that the chromoplast differentiation that occurs in the chloroplast during fruit ripening only occurs in RF, indicating that the lack of chromoplast biogenesis in BF leads to no sink for carotenoid storage and the failure to synthesize carotenoids. Similar enzyme activities of phytoene synthase 1 PSY1, chromoplast-specific lycopene β-cyclase CYC-B and β-carotene hydroxylase 2 CRTR-B2 were observed in both L. ruthenicum and L. barbarum, suggesting that the undetectable carotenoid levels in BF were not due to the inactivation of carotenoid biosynthetic enzymes. The transcript levels of the carotenoid biosynthetic genes, particularly PSY1, phytoene desaturase PDS, β-carotene desaturase ZDS, CYC-B and CRTR-B2, were greatly increased during RF ripening, indicating increased zeaxanthin biosynthesis. Additionally, carotenoid cleavage dioxygenase 4 CCD4 was expressed at much higher levels in BF than in RF, suggesting continuous carotenoid degradation in BF.

ConclusionsThe failure of the chromoplast development in BF causes low carotenoid biosynthesis levels and continuous carotenoid degradation, which ultimately leads to undetectable carotenoid levels in ripe BF. In contrast, the successful chromoplast biogenesis in RF furnishes the sink necessary for carotenoid storage. Based on this observation, the abundant zeaxanthin accumulation in RF is primarily determined via both the large carotenoid biosynthesis levels and the lack of carotenoid degradation, which are regulated at the transcriptional level.

KeywordsCarotenoids Chromoplast Fruit development Gene expression Lycium barbarum L. ruthenicum Electronic supplementary materialThe online version of this article doi:10.1186-s12870-014-0269-4 contains supplementary material, which is available to authorized users.

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Author: Yongliang Liu - Shaohua Zeng - Wei Sun - Min Wu - Weiming Hu - Xiaofei Shen - Ying Wang

Source: https://link.springer.com/







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