Regulation of carotenoid biosynthesis in petals and leaves of chrysanthemum (Chrysanthemum morifoliu

Regulation of carotenoid biosynthesis in petals and leaves of chrysanthemum (Chrysanthemum morifoliu

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Physiologia Plantarum 128: 436–447. 2006 Copyright ª Physiologia Plantarum 2006, ISSN 0031-9317 Regulation of carotenoid biosynthesis in petals and leaves of chrysanthemum ( Chrysanthemum morifolium ) Sanae Kishimoto* and Akemi Ohmiya National Institute of Floricultural Science, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan Correspondence *Corresponding author, e-mail: sanae@affrc.go.jp Received 27 October 2005; revised 24 January 2006 doi: 10.1111/j.1399-3054.2006.00761.x We analyzed carotenoid composition and the content and expression of genes encoding isoprenoid and carotenoid biosynthetic enzymes in petals and leaves of chrysanthemums. Most of the carotenoids in yellow petals were b , e -carotenoids, lutein and its derivatives, reflecting the high expression levels of lycopene e -cyclase ( LCYE ). In contrast, the ratio of b , b -carotenoids to total carotenoids in leaves were higher than that of b , e -carotenoids, reflecting the high expression levels of lycopen b -cyclase ( LCYB ). Petals of the yellow- flowered cultivar Yellow Paragon showed increased accumulation and drastic componential changes of carotenoids as they matured. In petals of the white- flowered cultivar Paragon, carotenoid content was drastically decreased during petal development and became less than the detection limit late in development. Transcript levels of most genes tested increased during petal development in Yellow Paragon. All genes except that for 1-deoxyxylulose 5- phosphate synthase ( DXS ) showed similar expression patterns in Paragon. Between-cultivar comparison of the expression of these genes in the petals at mid-development showed no distinct differences between petal color. It is possible that the formation of white petal color is due to neither down- regulation nor destruction of the carotenoid biosynthetic pathway. We presume that another factor inhibits carotenoid accumulation in chrysanthe- mum petals. Introduction Flowers owe their colors to flavones, anthocyanins, or carotenoids. Carotenoids are usually responsible for petal colors in the yellow to orange range. The role of these pigments is thought to be the attraction of insects that aid in pollination. In the green tissues of higher plants, carotenoids have an important function in protecting tissues against photooxidative damage (Britton 1988). With a few exceptions, carotenoids possess a terpenoid moiety and are C 40 isoprenoids. More than 700 naturally occurring carotenoids have now been identified (Britton et al. 2004). Carotenoid biosynthesis starts from one ‘isoprene unit’, C 5 -isopentenyl pyrophosphate (IPP). Four IPPs are condensed to C 20 -geranylgeranyl pyrophosphate (GGPP), and two molecules of GGPP are converted to phytoene, the first C 40 carotenoid, by phytoene synthase (PSY). In plants, phytoene is converted via z -carotene, the first yellow carotenoid, to lycopene by two structurally and functionally similar enzymes, phytoene desaturase (PDS) and z -carotene desaturase (ZDS). Subsequently, the ends of the linear carotenoid lycopene can be cyclized by lycopene b -cyclase (LCYB) and/or lycopene e -cyclase
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 12

Regulation of carotenoid biosynthesis in petals and leaves of chrysanthemum (Chrysanthemum morifoliu

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online