PJB-2018-285
Functional analysis of Lycopene β-cyclase genes from two watermelon cultivars LSW-177 (red-flesh) and COS (pale-yellow flesh)
Chuan Wu, Peng Gao, Shi Liu, Huiling Lv and Feishi Luan
Abstract
Carotenoid pigments are extensively found in plant tissues with multifunction. The specific carotenoids have been classified in plant photosynthetic centers and most of them are exclusively abundant in colorful fruits and vegetables. Previous results show that lycopene cyclases are fundamental for determining the proportion of carotenoids in fruit, leaves, flowers and roots. A quantitative trait locus (QTL) analysis exhibited that an enzyme is responsible for red versus non-red flesh in watermelon (Citrullus lanatus) and also correlated with the function of lycopene β-cyclase (lcyb) with flesh colour. The current study was conducted to characterize the two polymorphic genes encoding lcyb enzymes, from two watermelon cultivars (LSW-177and COS) containin the red and pale-yellow flesh, respectively. Results had confirmed the cyclase function of the two lcyb proteins in an Escherichia coli by heterologous complementation. These twolcyb proteins were differential in the amino acids at the 226th and 435th positions and had the effective ability to cyclase lycopene into bicyclic β-carotene, showing that these amino acid variations did not influence the functionality of lcyb enzymes in E. coli. In addition, the conversion of Ala168 to Glu168 by site-directed mutagenesis which inactivated the enzyme, suggested that this residue was part of the core region for lcyb function in watermelon. The results presented here will help more to clarify the mechanism by which lycopene β-cyclase performs its function
To Cite this article:
Wu, C., P. Gao, S. Liu, H. Lv and F. Luan. 2019. Functional analysis of Lycopene β-cyclase genes from two watermelon cultivars LSW-177 (red-flesh) and COS (pale-yellow flesh). Pak. J. Bot., 52(1): DOI: http://dx.doi.org/10.30848/PJB2020-1(19)
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