Gamma Irradiation Induced Transcriptional Repression of the Gibberellin Acid Regulating Genes in Arabidopsis Plants

초록

The model plant, Arabidopsis thaliana is the subject of an international genome researchproject. Massive doses of ionizing radiation have been shown to induce physiological changes inplants. The wild-type (Ler) Arabidopsis plants were irradiated with 100 Gy and 800 Gy of gammaray. Gibberellin (GA) affects developmental processes and responses according to the variousenvironment conditions in diverse plant. The 13 GA isomers were analyzed at vegetative (VE) andreproductive (RE) stages by HPLC. Total GA contents were reduced with the increase in radiationdoses at VE and RE stages. Specifically, levels of GA3, GA4, GA12, and GA34 were significantlyreduced with the increase of radiation doses. Oligonucleotide microarrays analysis was performedwith Arabidopsis plants at different developmental stages and doses of gamma-ray. Through themicroarray data, we isolated 41 genes related to GA biosynthesis and signaling transduction. Expression of these genes was also decreased as the reduction of GA contents. Interestingly, in GAsignaling related gene expression, gibberellin-responsive protein, putative (At2g18420) was downregulatedat VE and RE stages. Myb21 (At3g27810), Myb24 (At5g40350), and Myb57 (At3g01530)was down-regulated at RE stage. In GA biosynthesis related gene expression, YAP169 (At5g07200)and GA20ox2 (At5g51810) were down-regulated at 100 Gy treatment of VE stage and 800 Gy treatmentof RE stage in cytoplasm, respectively. However, exceptively, GA3ox2 (At1g80340) was upregulatedat 100 Gy treatment of RE stage in cytoplasm. In this study, the wild type (Ler) Arabidopsisplants showed differences in response with development stage at the various doses of gammarays. GA contents change was reported in gamma irradiated plant.

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