State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
Key Laboratory of Cotton Genetic Improvement, Ministry of Agriculture, Cotton Research Institute, Chinese Academy of Agriculture Sciences, Anyang, China.
Plant Biotechnol J. 2019 Mar;17(3):556-568. doi: 10.1111/pbi.12998. Epub 2018 Sep 4.
The HUB2 gene encoding histone H2B monoubiquitination E3 ligase is involved in seed dormancy, flowering timing, defence response and salt stress regulation in Arabidopsis thaliana. In this study, we used the cauliflower mosaic virus (CaMV) 35S promoter to drive AtHUB2 overexpression in cotton and found that it can significantly improve the agricultural traits of transgenic cotton plants under drought stress conditions, including increasing the fruit branch number, boll number, and boll-setting rate and decreasing the boll abscission rate. In addition, survival and soluble sugar, proline and leaf relative water contents were increased in transgenic cotton plants after drought stress treatment. In contrast, RNAi knockdown of GhHUB2 genes reduced the drought resistance of transgenic cotton plants. AtHUB2 overexpression increased the global H2B monoubiquitination (H2Bub1) level through a direct interaction with GhH2B1 and up-regulated the expression of drought-related genes in transgenic cotton plants. Furthermore, we found a significant increase in H3K4me3 at the DREB locus in transgenic cotton, although no change in H3K4me3 was identified at the global level. These results demonstrated that AtHUB2 overexpression changed H2Bub1 and H3K4me3 levels at the GhDREB chromatin locus, leading the GhDREB gene to respond quickly to drought stress to improve transgenic cotton drought resistance, but had no influence on transgenic cotton development under normal growth conditions. Our findings also provide a useful route for breeding drought-resistant transgenic plants.
H2B 单泛素化 E3 连接酶的 HUB2 基因参与拟南芥种子休眠、开花时间、防御反应和盐胁迫调节。在本研究中，我们使用花椰菜花叶病毒（CaMV）35S 启动子在棉花中驱动 AtHUB2 的过表达，发现它可以显著提高干旱胁迫条件下转基因棉花植物的农业性状，包括增加果枝数、棉铃数、坐铃率和降低棉铃脱落率。此外，在干旱胁迫处理后，转基因棉花植物的存活率和可溶性糖、脯氨酸和叶片相对含水量增加。相比之下，GhHUB2 基因的 RNAi 敲低降低了转基因棉花植物的抗旱性。AtHUB2 通过与 GhH2B1 的直接相互作用增加了全局 H2B 单泛素化（H2Bub1）水平，并上调了转基因棉花植物中与干旱相关基因的表达。此外，我们发现转基因棉花中 DREB 基因座处的 H3K4me3 显著增加，尽管在全局水平上没有发现 H3K4me3 的变化。这些结果表明，AtHUB2 过表达改变了 GhDREB 染色质基因座处的 H2Bub1 和 H3K4me3 水平，使 GhDREB 基因能够快速响应干旱胁迫，从而提高转基因棉花的抗旱性，但对转基因棉花在正常生长条件下的发育没有影响。我们的研究结果还为培育抗旱转基因植物提供了一条有用的途径。
