Regulation and manipulation of flavonoid gene expression in anthers of petunia: the molecular basis of the Po mutation

• Published in: The Plant cell Vol. 3; no. 1; pp. 39 - 48
• Main Authors: Tunen, A.J. van (Centre for Plant Breeding Research, Wageningen, The Netherlands), Mur, L.A, Recourt, K, Gerats, A.G.M, Mol, J.N.M
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Physiologists 01.01.1991
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Amino Acid Sequence; ANTERA; ANTHERE; Anthers; ARN; Base Sequence; Chalconoids; Complementary DNA; DNA; Enzymes; EXPRESION GENICA; EXPRESSION DES GENES; GENE; Gene Expression Regulation, Enzymologic; GENES; Genetic Complementation Test; Genetic Linkage; Genetic mutation; GENETICA; GENETIQUE; Intramolecular Lyases; ISOMERASAS; ISOMERASE; Isomerases - genetics; Molecular Sequence Data; MUTACION; MUTATION; NUCLEOTIDE; NUCLEOTIDOS; PETUNIA; PIGMENTACION; PIGMENTATION; Plants; Plants - enzymology; Plants - genetics; POLIMORFISMO; Pollen; POLYMORPHISME; Promoter regions; RNA probes; TECHNIQUE ANALYTIQUE; TECNICAS ANALITICAS; TRANSFORMACION GENETICA; TRANSFORMATION GENETIQUE
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.3.1.39

Molecular mechanisms governing development of the male reproductive organs of flowers, the anthers, are largely unknown. In this article, we report on the investigation of the molecular basis of a mutation involving the expression of a gene encoding the flavonoid biosynthesis enzyme chalcone flavanone isomerase (CHI) in anthers of petunia. in petunia, the gene Po regulates the expression of CHI in anthers: PoPo petunia lines contain CHI enzyme activity in petals and anthers, whereas popo lines contain the CHI enzyme only in petals but not in anthers. As a result of the Po mutation, the substrate of CHI accumulates and therefore the pollen of a popo line are yellow or greenish. The genome of petunia contains two chi genes, chiA and chiB. In a restriction fragment length polymorphism analysis, a 100% linkage was observed between Po and chiA. This result suggested that Po is identical to chiA and that Po is not a regulatory gene of chiA. Introduction of a chiA gene isolated from a PoPo line into a popo line resulted in a complementation of the mutation that was directly visible because the pollen color shifted from yellow to white. This proved that chiA and Po are identical. Because chiA encodes a functional CHI enzyme in flower petals of a popo line, we propose that the Po mutation is a mutation in the regulatory region of chiA abolishing chiA promoter activity in anthers but not in corollas. This change in anther color is a fine illustration of how floral pigmentation can be manipulated in a predictable way and suggests the use of CHI as a visible marker