Analysis of Effects of 24-Epibrassinolide and Boron Treatments on the Expression of CycD3;1, TCH4 and KOR Genes in Arabidopsis thaliana (L.) Heynh Seedlings using Semi-Quantitative RT-PCR
Brassinosteroids (BRs) play pivotal roles in plant cell division and cell elongation. Although boron (B) is an essential element for plants, excess B is toxic. In this study, we investigated the effects of 24-Epibrassinolide (EBL) on expression of cell cycle (CycD3;1) and cell wall-related (TCH4 and KOR) genes in leaf and root tissues of Arabidopsis thaliana (L.) Heynh seedlings under high concentrations of boric acid (BA) using semi-quantitative reverse transcriptase – polymerase chain reaction (RT-PCR). A. thaliana seedlings were grown in a hydroponic culture for four weeks, and then transferred to liquid media containing BA (50 and 100 mg L-1) and/or EBL (0.01 and 1 μM) and incubated for 60 hours. In root tissues, BA treatments decreased the expression of CycD3;1 gene, whereas 0.01 μM EBL treatments increased the expression level of this gene when compared with plants exposed to BA alone. 1 μM EBL alone or in combination with BA treatments significantly led to down regulation of CycD3;1 gene. On the other hand, application of 1 μM EBL resulted in significant increase of mRNA levels of KOR and TCH4 genes in root tissues. In leaf tissues, no significant differences were observed in the expression levels of CycD3;1 and KOR genes as a result of all treatments. BA treatments increased the expression levels of TCH4 gene significantly when compared to control in leaf tissues. To conclude, the results showed that EBL in general positively regulate the expression of cell cycle and cell-wall related genes under high B stress and stress-free conditions.