Differential expression of fatty acid synthase genes, Acl, Fat and Kas, in Capsicum fruit.
The biosynthesis of capsaicinoids in the placenta of chilli fruit is modelled to require components of the fatty acid synthase (FAS) complex. Three candidate genes for subunits in this complex, Kas, Acl, and Fat, isolated based on differential expression, were characterized. Transcription of these three genes was placental-specific and RNA abundance was positively correlated with degree of pungency. Kas and Acl were mapped to linkage group 1 and Fat to linkage group 6. None of the genes is linked to the pungency locus, C, on linkage group 2. KAS accumulation was positively correlated with pungency. Western blots of placental extracts and histological sections both demonstrated that the accumulation of this enzyme was correlated with fruit pungency and KAS was immunolocalized to the expected cell layer, the placental epidermis. Enzyme activity of the recombinant form of the placental-specific KAS was confirmed using crude cell extracts. These FAS components are fruit-specific members of their respective gene families. These genes are predicted to be associated with Capsicum fruit traits, for example, capsaicinoid biosynthesis or fatty acid biosynthesis necessary for placental development.
Aluru
Maneesha R
MR
Department of Agronomy and Horticulture, MSC 3Q, PO Box 30003, New Mexico State University, Las Cruces, NM 88003, USA.
Mazourek
Michael
M
Landry
Laurie G
LG
Curry
Jeanne
J
Jahn
Molly
M
O'Connell
Mary A
MA
D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000235:genetics* / Q000378:metabolism; D000213:Acyl Carrier Protein / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D002211:Capsaicin / Q000378:metabolism; D002212:Capsicum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000235:genetics* / Q000378:metabolism; D005638:Fruit / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013869:Thiolester Hydrolases / Q000235:genetics* / Q000378:metabolism
D000213:Acyl Carrier Protein; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C018748:oleoyl-(acyl-carrier-protein) hydrolase; D002211:Capsaicin