Kazama Daisuke, Kurusu Takamitsu, Mitsuda Nobutaka, Ohme-Takagi Masaru, Tada Yuichi
Graduate School of Bionics; Tokyo University of Technology; Hachioji, Tokyo, Japan.
School of Bioscience and Biotechnology; Tokyo University of Technology; Hachioji, Tokyo, Japan.
Plant Signal Behav. 2014;9(3):e28211. doi: 10.4161/psb.28211. Epub 2014 Mar 10.
Arabidopsis plants transformed with a chimeric repressor for 6 transcription factors (TFs), including ADA2b, Msantd, DDF1, DREB26, AtGeBP, and ATHB23, that were converted by Chimeric REpressor gene Silencing Technology (CRES-T), show elevated salt and osmotic stress tolerance compared with wild type (WT) plants. However, the roles of TFs in salt and osmotic signaling remain largely unknown. Their hyper-osmotic stress tolerance was evaluated using 3 criteria: germination rate, root length, and rate of seedlings with visible cotyledons at the germination stage. All CRES-T lines tested exhibited better performance than WT, at least for one criterion under stress conditions. Under 600 mM mannitol stress, 3-week-old CRES-T lines accumulated proline, which is a major compatible solute involved in osmoregulation, at higher levels than WT. Expression levels of the delta 1-pyrroline-5-carboxylate synthase gene in CRES-T lines were similar to or lower than those in WT. In contrast, expression of the proline dehydrogenase (PHD) gene in DREB26-SRDX was significantly downregulated and that in ADA2b-SRDX and AtGeBP-SRDX was also rather downregulated compared with that in WT. Although plants at different stages were used for stress tolerance test and proline measurement in this study, we previously reported that 4 out of the 6 CRES-T lines showed better growth than WT after 4 weeks of incubation under 400 mM mannitol. These results suggest that proline accumulation caused by PHD gene suppression may be involved in enhanced osmotic stress tolerance in the CRES-T lines, and that these TFs may be involved in regulating proline metabolism in Arabidopsis.
用嵌合阻遏物转化的拟南芥植株，该嵌合阻遏物针对6种转录因子（TFs），包括ADA2b、Msantd、DDF1、DREB26、AtGeBP和ATHB23，这些转录因子通过嵌合阻遏基因沉默技术（CRES-T）进行了转化，与野生型（WT）植株相比，表现出更高的盐胁迫和渗透胁迫耐受性。然而，转录因子在盐胁迫和渗透信号传导中的作用在很大程度上仍然未知。使用三个标准评估它们的高渗胁迫耐受性：发芽率、根长和发芽阶段有可见子叶的幼苗率。所有测试的CRES-T系在胁迫条件下至少在一个标准上表现优于野生型。在600 mM甘露醇胁迫下，3周龄的CRES-T系积累脯氨酸，脯氨酸是参与渗透调节的主要相容性溶质，其积累水平高于野生型。CRES-T系中δ1-吡咯啉-5-羧酸合成酶基因的表达水平与野生型相似或低于野生型。相反，与野生型相比，DREB26-SRDX中脯氨酸脱氢酶（PHD）基因的表达显著下调，ADA2b-SRDX和AtGeBP-SRDX中的表达也相当下调。尽管本研究中使用了不同阶段的植株进行胁迫耐受性测试和脯氨酸测量，但我们之前报道过，6个CRES-T系中有4个在400 mM甘露醇下培养4周后生长比野生型更好。这些结果表明，PHD基因抑制引起的脯氨酸积累可能参与了CRES-T系中渗透胁迫耐受性的增强，并且这些转录因子可能参与调节拟南芥中的脯氨酸代谢。
