| Summary: | 碩士 === 國立屏東科技大學 === 農園生產系 === 93 === Flowering is an important physiological transition process in the plant life cycle, and is affected by many environmental and endogenous signals. It has been shown that the LFY (LEAFY)/FLO (FLORICAULA) gene and its homologs control the vegetative to reproductive transition as well as floral development in diverse plants. In this study, a LFY gene and its promoter were cloned from longan. The effect of potassium chlorate-induced flowering on the expression of LFY was also investigated. Part of the LFY gene was isolated from cDNA derived from opened longan flowers using degenerate primers. The complete gene and 5’ flanking sequences were obtained using 3’-RACE and genome walking approaches. This gene was designated as DlLFY. The full length of the cloned DlLFY cDNA was 1,391bp, which contains a 3’-UTR of 221bp and putative 1,167bp ORF encoding a polypeptide of 389 amino acids. There were at least one copy of DlLFY present in the longan genome according to Southern blot analysis. DlLFY contains a poline-rich region and basic and acidic regions. The predicted amino acid sequences of DlLFY share 69 and 68% similarity with CsLFY and PtLF cloned from Citrus sinensis and Populus trichocarpa, respectively. DlLFY has two highly conserved regions from amino acids 53 to 122 and 215 to 303, respectively. RT-PCR analysis showed that DlLFY was expressed with the highest level in young leaves and opened flowers, and had lower expression in mature leaves and fruits. However, expression in roots was not detected. The expression in mature leaves remained low from potassium chlorate treatment until blooming. Sequence analysis of promoter reveals photoperiod and gibberellins response-related cis-acting elements.
Keyword: longan, flowering, potassium chlorate, LEAFY
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