Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Ji'nan, Shandong, PR China; Maize Research Institute, Shandong Academy of Agricultural Sciences, Ji'nan, Shandong, PR China.
Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Ji'nan, Shandong, PR China.
Plant Sci. 2021 Jan;302:110704. doi: 10.1016/j.plantsci.2020.110704. Epub 2020 Oct 7.
Arabidopsis thaliana TRY is a negative regulator of trichome differentiation that promotes root hair differentiation. Here, we established that LbTRY, from the recretohalophyte Limonium bicolor, is a typical MYB transcription factor that exhibits transcriptional activation activity and locates in nucleus. By in situ hybridization in L. bicolor, LbTRY may be specifically positioned in salt gland of the expanded leaves. LbTRY expression was the highest in mature leaves and lowest under NaCl treatment. For functional assessment, we heterologously expressed LbTRY in wild-type and try29760 mutant Arabidopsis plants. Epidermal differentiation was remarkably affected in the transgenic wild-type line, as was increased root hair development. Complementation of try29760 with LbTRY under both 35S and LbTRY specific promoter restored the wild-type phenotype. qRT-PCR analysis suggested that AtGL3 and AtZFP5 promote root hair cell fate in lines heterologously producing LbTRY. In addition, four genes (AtRHD6, AtRSL1, AtLRL2, and AtLRL3) involved in root hair initiation and elongation were upregulated in the transgenic lines. Furthermore, LbTRY specifically increased the salt sensitivity of the transgenic lines. The transgenic and complementation lines showed poor germination rates and reduced root lengths, whereas the mutant unexpectedly fared the best under a range of NaCl treatments. Under salt stress, the transgenic seedlings accumulated more MDA and Na and less proline and soluble sugar than try29760. Thus, when heterologously expressed in Arabidopsis, LbTRY participates in hair development, similar to other MYB proteins, and specifically reduces salt tolerance by increasing ion accumulation and reducing osmolytes. The expression of salt-tolerance marker genes (SOS1, SOS2, SOS3 and P5CS1) was significant reduced in the transgenic lines. More will be carried by downregulating expression of TRY homologs in crops to improve salt tolerance.
拟南芥 TRY 是毛状体分化的负调控因子，促进根毛分化。在这里，我们确定来自盐生植物二色补血草的 LbTRY 是一种典型的 MYB 转录因子，具有转录激活活性并定位于细胞核中。通过在二色补血草中进行原位杂交，LbTRY 可能特异性定位于扩展叶片的盐腺中。LbTRY 的表达在成熟叶片中最高，在 NaCl 处理下最低。为了进行功能评估，我们在野生型和 try29760 突变体拟南芥植物中异源表达 LbTRY。在转基因野生型系中，表皮分化受到显著影响，根毛发育也增加。在 35S 和 LbTRY 特异性启动子下，用 LbTRY 互补 try29760 恢复了野生型表型。qRT-PCR 分析表明，在异源产生 LbTRY 的系中，AtGL3 和 AtZFP5 促进根毛细胞命运。此外，在转基因系中，四个参与根毛起始和伸长的基因（AtRHD6、AtRSL1、AtLRL2 和 AtLRL3）上调。此外，LbTRY 特异性增加了转基因系的盐敏感性。转基因和互补系的发芽率低，根长短，而突变体在一系列 NaCl 处理下表现最好。在盐胁迫下，与 try29760 相比，转基因幼苗积累了更多的 MDA 和 Na，而脯氨酸和可溶性糖则更少。因此，当在拟南芥中异源表达时，LbTRY 参与毛发生长，类似于其他 MYB 蛋白，通过增加离子积累和减少渗透物来特异性降低耐盐性。转基因系中盐胁迫标记基因（SOS1、SOS2、SOS3 和 P5CS1）的表达显著降低。通过下调作物中 TRY 同源物的表达，可以进一步提高耐盐性。
