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Isolation and functional characterisation of banana phytoene synthase genes as potential cisgenes

Mlalazi, Bulukani, Welsch, Ralf, Namanya, Priver, Khanna, Harjeet K., Geijskes, R. Jason, Harrison, Mark D., Harding, Robert M., Dale, James L., & Bateson, Marion (2012) Isolation and functional characterisation of banana phytoene synthase genes as potential cisgenes. Planta.

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Abstract

Carotenoids occur in all photosynthetic organisms where they protect photosystems from auto-oxidation, participate in photosynthetic energy-transfer and are secondary metabolites. Of the more than 600 known plant carotenoids, few can be converted into vitamin A by humans and so these pro-vitamin A carotenoids (pVAC) are important in human nutrition. Phytoene synthase (PSY) is a key enzyme in the biosynthetic pathway of pVACs and plays a central role in regulating pVAC accumulation in the edible portion of crop plants. Bananas are a major commercial crop and serve as a staple crop for more than 30 million people. There is natural variation in fruit pVAC content across different banana cultivars, but this is not well understood. Therefore, we isolated PSY genes from banana cultivars with relatively high (cv. Asupina) and low (cv. Cavendish) pVAC content. We provide evidence that PSY in banana is encoded by two paralogs (PSY1 and PSY2), each with a similar gene structure to homologous genes in other monocots. Further, we demonstrate that PSY2 is more highly expressed in fruit pulp compared to leaf. Functional analysis of PSY1 and PSY2 in rice callus and E. coli demonstrate that both genes encode functional enzymes, and that Asupina PSYs have approximately twice the enzymatic activity of the corresponding Cavendish PSYs. These results suggest that differences in PSY enzyme activity contribute significantly to the differences in Asupina and Cavendish fruit pVAC content. Importantly, Asupina PSY genes could potentially be used to generate new cisgenic or intragenic banana cultivars with enhanced pVAC content.

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4 citations in Scopus
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4 citations in Web of Science®

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ID Code: 52937
Item Type: Journal Article
Keywords: Biofortification, Carotene, Cisgenic, Intragenic, Isoprenoid, Metabolic engineering
DOI: 10.1007/s00425-012-1717-8
ISSN: 1432-2048
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000)
Australian and New Zealand Standard Research Classification > AGRICULTURAL AND VETERINARY SCIENCES (070000)
Divisions: Current > Research Centres > Centre for Tropical Crops and Biocommodities
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 Springer-Verlag
Copyright Statement: The original publication is available at SpringerLink http://www.springerlink.com
Deposited On: 06 Aug 2012 09:29
Last Modified: 10 Aug 2012 18:43

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