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SUMMARY:Exploiting natural variation to identify genes that impact nutriti
 onal seed traits - Sabrina Gonzalez-Jorge\, Henderson Group
DTSTART:20161201T130000Z
DTEND:20161201T133000Z
UID:TALK67643@talks.cam.ac.uk
CONTACT:42122
DESCRIPTION:Carotenoids are vital to numerous physiological processes in p
 lants and animals as structural components of the photosynthetic apparatus
 \, hormone precursors\, photoprotectants and antioxidants. Animals depend 
 on dietary intake of carotenoids\, especially of vitamin A precursors such
  as α- and β-carotene\, to meet their daily health demands. Vitamin A de
 ficiency is prevalent in much of the developing world\, mainly because die
 ts are based on staple crop seeds with low carotenoid or provitamin A cont
 ent. A fully elucidated plant carotenoid pathway has allowed successful en
 gineering of carotenoid-enriched crops (e.g. rice)\, but these efforts hav
 e been limited to plant carotenoid biosynthesis genes\, though QTL analysi
 s makes clear that in addition to biosynthetic genes other novel loci sign
 ificantly contribute to the natural variation of carotenoids in crops. To 
 identify such loci\, the natural variation of Arabidopsis seed carotenoids
  was explored by quantitative trait loci (QTL) analysis and genome wide as
 sociation studies (GWAS). Using two recombinant inbred line (RIL) populati
 ons\, a carotenoid cleavage dioxygenase 4\, CCD4\, with LOD scores >10 and
  explaining >40% phenotypic variation was identified through QTL fine mapp
 ing. Concurrently\, a genome wide significant association for seed β-caro
 tene was mapped to the coding region of CCD4. Functional characterization 
 showed CCD4 to be highly expressed during late embryogenesis and desiccati
 on stages (18-21 DAP) of seed development. The  Arabidopsis ccd4 null muta
 nt resulted in a 13.3-fold increased mature-seed β-carotene content relat
 ive to wild type and complementation of this line with superior and inferi
 or CCD4 alleles confirmed the QTL is this gene. These data coupled with th
 e identification of CCD4 by both QTL and GWAS\, highlight the functional s
 ignificance of this enzyme as a novel and important regulator of carotenoi
 d homeostasis in Arabidopsis seeds. The identification of such regulatory 
 components of seed provitamin A content will be critical to enhancing crop
  breeding and genetic engineering efforts tasked with tackling provitamin 
 A deficiency.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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