Distribution of Gibberellins and Expressional Analysis of GA 20-oxidase Genes of Morning Glory during Fruit Maturation
2005
NAKAYAMA, Akira | Nakajima, Masatoshi | YAMAGUCHI, Isomaro
Gibberellins A₁⁄₃ (GA₁⁄₃) and GA₂₀ appeared earlier in surrounding tissues (pericarps/carpel/placenta) than in developing seeds of morning glory. The content of GA₁⁄₃ became higher in seeds than in the surrounding tissues at 9 days after anthesis (DAA), while that of GA₂₀ stayed lower in seeds even at 12 DAA, suggesting the possibility that GA₂₀ was translocated into seeds from the surrounding tissues and converted to GA₁⁄₃. The site of biosynthesis of GA₂₀ in the fruits was determined by RNA-blotting and in situ hybridization of GA 20-oxidase genes (InGA20ox1, InGA20ox2). InGA20ox1 was not expressed in the surrounding tissues but in seeds, while no signal due to InGA20ox2 was detected in neither tissue. The expression of InGA20ox1 started in the seed coat near the hilum and spread in the seed coat like those of GA 3-oxidase and GA-inducible α-amylase genes. These observations suggest that GA biosynthesis is tissue-specifically and time-dependently regulated in the fruit of morning glory.
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