Article

The b Gene of Pea Encodes a Defective Flavonoid 3',5'-Hydroxylase, and Confers Pink Flower Color

Department of Metabolic Biology, John Innes Centre, Norwich, United Kingdom.
Plant physiology (Impact Factor: 6.84). 04/2012; 159(2):759-68. DOI: 10.1104/pp.112.197517
Source: PubMed

ABSTRACT

The inheritance of flower color in pea (Pisum sativum) has been studied for more than a century, but many of the genes corresponding to these classical loci remain unidentified. Anthocyanins are the main flower pigments in pea. These are generated via the flavonoid biosynthetic pathway, which has been studied in detail and is well conserved among higher plants. A previous proposal that the Clariroseus (B) gene of pea controls hydroxylation at the 5' position of the B ring of flavonoid precursors of the anthocyanins suggested to us that the gene encoding flavonoid 3',5'-hydroxylase (F3'5'H), the enzyme that hydroxylates the 5' position of the B ring, was a good candidate for B. In order to test this hypothesis, we examined mutants generated by fast neutron bombardment. We found allelic pink-flowered b mutant lines that carried a variety of lesions in an F3'5'H gene, including complete gene deletions. The b mutants lacked glycosylated delphinidin and petunidin, the major pigments present in the progenitor purple-flowered wild-type pea. These results, combined with the finding that the F3'5'H gene cosegregates with b in a genetic mapping population, strongly support our hypothesis that the B gene of pea corresponds to a F3'5'H gene. The molecular characterization of genes involved in pigmentation in pea provides valuable anchor markers for comparative legume genomics and will help to identify differences in anthocyanin biosynthesis that lead to variation in pigmentation among legume species.

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Available from: Julie Hofer, Feb 18, 2014
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    • "These studies, together with the results presented here, indicate that a range of deletion sizes exists in the population and that individual lines could carry more than one mutation. For the deletion alleles of the mutants listed in Table 2, one rearrangement (Moreau et al. 2012) that appears to result from a non-homologous exchange involving an Ogre element was found, and two were small deletions, one of 22 bp (Hellens et al. 2010) and the other of 1.4 kb (Moreau et al. 2012); the remaining 25 alleles were all larger than the gene being characterised. "
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    ABSTRACT: A fast neutron (FN)-mutagenised population was generated in Pisum sativum L. (pea) to enable the identification and isolation of genes underlying traits and processes. Studies of several phenotypic traits have clearly demonstrated the utility of the resource by associating gene deletions with phenotype followed by functional tests exploiting additional mutant sources, from both induced and natural variant germplasm. For forward genetic screens, next generation sequencing methodologies provide an opportunity for identifying genes associated with deletions rapidly and systematically. The application of rapid reverse genetic screens of the fast neutron mutant pea population supports conclusions on the frequency of deletions based on phenotype alone. These studies also suggest that large deletions affecting one or more loci can be non-deleterious to the pea genome, yielding mutants that could not be obtained by other means. Deletion mutants affecting genes associated with seed metabolism and storage are providing unique opportunities to identify the products of complex and related gene families, and to study the downstream consequences of such deletions.
    Full-text · Article · Aug 2013 · Functional Plant Biology
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    • "However this later statement is not always easy to verify: for instance, it is not clear if the pea strains studied by Gregor Mendel should be considered as mutants or cultivars, but the recent mapping studies of pea color phenotypes were included here (Hellens et al. 2010; Moreau et al. 2012). Thus, the boundary between mutants and bona fide selected phenotypes can be blurry. "

    Full-text · Dataset · May 2013
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    • "However this later statement is not always easy to verify: for instance, it is not clear if the pea strains studied by Gregor Mendel should be considered as mutants or cultivars, but the recent mapping studies of pea color phenotypes were included here (Hellens et al. 2010; Moreau et al. 2012). Thus, the boundary between mutants and bona fide selected phenotypes can be blurry. "

    Full-text · Dataset · May 2013
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