Miyazaki Yuji, Abe Hiroshi, Takase Tomoyuki, Kobayashi Masatomo, Kiyosue Tomohiro
Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan.
Plant Cell Rep. 2015 May;34(5):843-52. doi: 10.1007/s00299-015-1746-4. Epub 2015 Jan 28.
The overexpression of LKP2 confers dehydration tolerance in Arabidopsis thaliana ; this is likely due to enhanced expression of dehydration-inducible genes and reduced stomatal opening. LOV KELCH protein 2 (LKP2) modulates the circadian rhythm and flowering time in plants. In this study, we observed that LKP2 overexpression enhanced dehydration tolerance in Arabidopsis. Microarray analysis demonstrated that expression of water deprivation-responsive genes was higher in the absence of dehydration stress in transgenic Arabidopsis plants expressing green fluorescent protein-tagged LKP2 (GFP-LKP2) than in control transgenic plants expressing GFP. After dehydration followed by rehydration, GFP-LKP2 plants developed more leaves and roots and exhibited higher survival rates than control plants. In the absence of dehydration stress, four dehydration-inducible genes, namely DREB1A, DREB1B, DREB1C, and RD29A, were expressed in GFP-LKP2 plants, whereas they were not expressed or were expressed at low levels in control plants. Under dehydration stress, the expression of DREB2B and RD29A peaked faster in the GFP-LKP2 plants than in control plants. The stomatal aperture of GFP-LKP2 plants was smaller than that of control plants. These results suggest that the dehydration tolerance of GFP-LKP2 plants is caused by upregulation of DREB1A-C/CBF1-3 and their downstream targets; restricted stomatal opening in the absence of dehydration stress also appears to contribute to the phenotype. The rapid and high expression of DREB2B and its downstream target genes also likely accounts for some features of the GFP-LKP2 phenotype. Our results suggest that LKP2 can be used for biotechnological applications not only to adjust the flowering time control but also to enhance dehydration tolerance.
LKP2的过表达赋予拟南芥脱水耐受性；这可能是由于脱水诱导基因的表达增强以及气孔开度减小。LOV Kelch蛋白2（LKP2）调节植物的昼夜节律和开花时间。在本研究中，我们观察到LKP2过表达增强了拟南芥的脱水耐受性。微阵列分析表明，在表达绿色荧光蛋白标记的LKP2（GFP-LKP2）的转基因拟南芥植物中，缺水响应基因在无脱水胁迫时的表达高于表达GFP的对照转基因植物。脱水后再复水，GFP-LKP2植物比对照植物长出更多的叶和根，且存活率更高。在无脱水胁迫时，四个脱水诱导基因，即DREB1A、DREB1B、DREB1C和RD29A，在GFP-LKP2植物中表达，而在对照植物中不表达或低水平表达。在脱水胁迫下，GFP-LKP2植物中DREB2B和RD29A的表达峰值比对照植物更快。GFP-LKP2植物的气孔孔径小于对照植物。这些结果表明，GFP-LKP2植物的脱水耐受性是由DREB1A-C/CBF1-3及其下游靶标的上调引起的；在无脱水胁迫时气孔开度受限似乎也对该表型有贡献。DREB2B及其下游靶标基因的快速和高表达也可能是GFP-LKP2表型某些特征的原因。我们的结果表明，LKP2不仅可用于生物技术应用来调节开花时间控制，还可增强脱水耐受性。
