title: Expression level of a flavonoid 3'-hydroxylase gene determines pathogen-induced color variation in sorghum.
abstract: BACKGROUND
  Sorghum (Sorghum bicolor L. Moench) accumulates 3-deoxyanthocyanidins and exhibits orange to purple coloration on parts of the leaf in response to infection with the fungus Bipolaris sorghicola. We aimed to identify the key genes determining this color variation.
  
  
  RESULTS
  Sorghum populations derived from Nakei-MS3B and M36001 accumulated apigeninidin, or both apigeninidin and luteolinidin, in different proportions in lesions caused by B. sorghicola infection, suggesting that the relative proportions of the two 3-deoxyanthocyanidins determine color variation. QTL analysis and genomic sequencing indicated that two closely linked loci on chromosome 4, containing the flavonoid 3'-hydroxylase (F3'H) and Tannin1 (Tan1) genes, were responsible for the lesion color variation. The F3'H locus in Nakei-MS3B had a genomic deletion resulting in the fusion of two tandemly arrayed F3'H genes. The recessive allele at the Tan1 locus derived from M36001 had a genomic insertion and encoded a non-functional WD40 repeat transcription factor. Whole-mRNA sequencing revealed that expression of the fused F3'H gene was conspicuously induced in purple sorghum lines. The levels of expression of F3'H matched the relative proportions of apigeninidin and luteolinidin.
  
  
  CONCLUSIONS
  Expression of F3'H is responsible for the synthesis of luteolinidin; the expression level of this gene is therefore critical in determining color variation in sorghum leaves infected with B. sorghicola.
authors.affiliation: National Institute of Agrobiological Sciences, Agrogenomics Research Center, 1-2, Kannondai 2-chome, Tsukuba, Ibaraki 305-8602, Japan. hmizuno@nias.affrc.go.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuno
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yazawa
authors.forename: Shigemitsu
authors.initials: S
authors.lastname: Kasuga
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sawada
authors.forename: Jun
authors.initials: J
authors.lastname: Ogata
authors.forename: Tsuyu
authors.initials: T
authors.lastname: Ando
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanamori
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Yonemaru
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Wu
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawahigashi
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D047310:Apigenin / Q000378:metabolism; D001203:Ascomycota / Q000472:pathogenicity*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D050939:Gene Fusion; D056726:Genetic Association Studies; D018745:Genome, Plant; D054884:Host-Pathogen Interactions; D009181:Mycoses / Q000201:enzymology / Q000382:microbiology*; D010858:Pigmentation; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000201:enzymology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D040641:Quantitative Trait Loci; D045868:Sorghum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology*; D059467:Transcriptome; D000094162:Phytoalexins
chemical_list: D000872:Anthocyanins; D047310:Apigenin; D003577:Cytochrome P-450 Enzyme System; D010940:Plant Proteins; C104027:apigeninidin; D000094162:Phytoalexins; C038888:flavonoid 3'-hydroxylase; C518537:luteolinidin