27.レタスのLsGA3ox1欠損突然変異体の特徴付け(口頭発表)

概要

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It was previously shown that up-regulation of LsGA3ox1 and LsGA3ox2 is involved in increment of endogenous level of GA_1 physiologically active gibberellin, after red light irradiation in photoblastic lettuce (Lactuca sativa L. cv. Grand Rapids) seeds. Both of LsGA3ox1 and LsGA3ox2 encode gibberellin 3-oxidases that directly act in activation of gibberellins. Recently, gene tagging in lettuce using the Tnt1 retrotransposon from tobacco was carried out. Among a series of mutant lines in cv. Jessy background, a loss-of-LsGA3ox1-function mutant (JesTnt6a), which exhibited the gibberellin-deficient dwarf phenotype, was found. In this study, we characterized homozygous JesTnt6a mutant to elucidate the physiological role of LsGA3ox1 in lettuce. It was shown that Tnt1 is inserted into the sole intron of LsGA3ox1 by sequencing a PCR fragment. However, results by QRT-PCR analysis suggested that LsGA3ox1 is almost knocked out in the JesTnt6a mutant: level of mature LsGA3ox1 transcript in the JesTnt6a seedlings was extremely (approximately 1/1000 times) lower than that in the wild type Jessy seedlings. Germination assay indicated that not only wild type Jessy seeds but also JesTnt6a seeds germinated in the continuous white light, probably due to functional redundancy with other gibberellin 3-oxidase genes, such as LsGA3ox2.
2008-10-06