title: Involvement of multiple phytoene synthase genes in tissue- and cultivar-specific accumulation of carotenoids in loquat.
abstract: Differences in carotenoid accumulation between tissues and cultivars is common in plants. White-fleshed loquat cultivars had low levels of carotenoids in the flesh, but accumulated carotenoids in peel when ripe, and the leaves accumulated similar carotenoids to those in the red-fleshed loquat cultivars. The catalytic activity and expression patterns of four phytoene synthase (PSY) genes, EjPSY1, EjPSY2A, EjPSY2B, and EjPSY3, were analysed to understand their roles in different loquat (Eriobotrya japonica Lindl.) types. EjPSY1 was responsible for carotenoid synthesis in the fruit peel but not the flesh, whereas EjPSY2A was responsible for carotenoid accumulation in flesh of ripening fruit. A mutant EjPSY2A (d) , with the same tissue specificity and expression level as EjPSY2A, but lacking the C-terminal region and corresponding catalytic activity, was discovered in white-fleshed varieties, explaining the lack of carotenoids in the white flesh. The catalytic role of EjPSY2B was most significant in leaves. The tissue-specific expression of EjPSY1 and EjPSY2B explained well how peel and leaf tissues can still accumulate carotenoids in white-fleshed cultivars, which have lost the functional EjPSY2A. EjPSY3 mRNA abundance was ~1000-fold less than that of other PSY mRNAs in all tissues examined. In addition, neither the normal sized transcript nor two alternatively spliced forms, EjPSY3α in LYQ and EjPSY3β in BS cultivars, encoded functional enzymes, and it is concluded that EjPSY3 plays no role in carotenoid accumulation. In addition, it was noted that recruitment of PSY genes for expression in specific tissues of different plants has occurred independently of gene structure and evolutionary origin.
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou 510650, China.
authors.forename: Xiumin
authors.initials: X
authors.lastname: Fu
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Feng
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Wang
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: Xueren
authors.initials: X
authors.lastname: Yin
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: Pengjun
authors.initials: P
authors.lastname: Lu
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China Plant & Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
authors.forename: Don
authors.initials: D
authors.lastname: Grierson
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China chjxu@zju.edu.cn.
authors.forename: Changjie
authors.initials: C
authors.lastname: Xu
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
authors.forename: Kunsong
authors.initials: K
authors.lastname: Chen
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D060146:Ecotype; D031983:Eriobotrya / Q000201:enzymology* / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005808:Genes, Recessive; D005816:Genetic Complementation Test; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase / Q000235:genetics* / Q000378:metabolism; D009928:Organ Specificity / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D002338:Carotenoids; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase
keywords: Carotenoid; function; loquat (Eriobotrya japonica); mutation; phytoene synthase; tissue-specific expression.