서강대학교

초록/요약

Plants have evolved sophisticated mechanisms to adapt to environmental stresses. Gene regulations at the transcription and post-transcription levels are highly associated with their growth, development and stress response. In Arabidopsis, STABILIZED1 (STA1) encodes a nuclear protein similar to the human U5 small ribonucleoprotein-associated 102-KDa protein and to the yeast pre-mRNA splicing factors, Prp1p and Prp6p. STA1 expression is upregulated by cold and heat stress. In addition, sta1-1 mutant showed defective splicing of the cold-induced COR15A gene and several heat-inducible transcription factors. To elucidate the potential functions of STA1 in response to stresses, we generated STA1 overexpressor (STA1 OE) transgenic plants and investigated their phenotypes in comparison to the wild-type Arabidopsis plants (ColRDLUC, a Columbia gl1 line harboring the stress-inducible RD29A promoter-driven luciferase gene) under normal and stress conditions. By using the Agrobacterium-mediated method, we introduced the STA1 overexpressing transgene to ColRDLUC to generate the STA1 OE lines. STA1 OE displayed similarly in size and height compared to the wild-type, hence bigger than sta1-1 mutants. Interestingly, STA1 OE transgenic plants showed earlier bolting time than wild-type and sta1-1. The accumulation of miR156 and miR172 in STA1 OE is similar to wild type which show anti parallel pattern responding to plant age, miR156 was decreased at 24-day-old but apparently lower compare to decreasing in wild type plant and less increasing of miR172 at 24-day-old in STA1 OE compare to wild type. Upregulation of SPL9 and AP2 genes that target by miR156 and miR172, respectively was confirmed by RT-PCR. In response to heat stress, STA1 OE showed heat tolerant phenotype as evidenced by their longer hypocotyl and root length than the wild-type. Longer hypocotyl phenotypes in STA1 OE under heat were correlated with increased expression of PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) in STA1 OE under heat. However, splicing of HEAT SHOCK FACTORs (HSFs) was not further enhanced in STA1 OE Arabidopsis transgenic plant after heat treatment and was comparable to one in ColRDLUC. To elucidate the biological function of Arabidopsis STA1 in a crop plant, we attempted to generate transgenic Brassica napus plants overexpressing the STA1 gene. Six independent lines of Brassica napus transgenic plants were successful generated. Semi-quantitative RT-PCR showed that all tested transgenic plants accumulated high amounts of Arabidopsis STA1 gene transcripts.