| Summary: | 碩士 === 國立中央大學 === 生命科學研究所 === 98 === Previously, in order to understand the mechanisms of plant tolerance, we used chemical mutagen EMS to generate point mutation and isolated a heat intolerant mutant from Arabidopsis which is named hit1. HIT1 locus was later identified to be on the chromosome Ι and amino acid analysis showed that HIT1 is homologous to yeast Vps53p. In order to understand the physiological function of HIT1, we use HIT1 promoter driven -glucuromidase (GUS) reporter gene to observe the expression pattern in plant. Result showed that HIT1 expression only at elongation zone of root,stigma and pollen tube. DNA sequence analysis further indicated that there are two anther/pollen-specific elements GTGA and AGAAA present in HIT1 promoter. It
might be the cause of the observed organ/tissue expression specificity. Moreover, in order to dissect the regions that lead to the HIT1 expression specificity, a series of
5’-deletion of HIT1 promoter were generated by PCR from Columbia (WT) to drive GUS reporter gene. Results indicated that HIT1-D3 might have important element that
deletion of such region can inhibit HIT1 gene expression. Sequence analysis also showed a G-box which may be an important regulatory element of the gene. The 5'' untranslated region also showed effects on HIT1 gene expression, possibly through post- transcriptional regulation. In the mean time, another EMS-mutagenized heat
intolerant mutant, hit3, was isolated from Arabidopsis. The locus of hit3 currently mapped to chromosome Ⅴ. More genetic analysis and physiological test of the hit3
mutant should provide insight to the complexity of plant heat tolerance.
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