转录因子ZxNAC018和ZxNAC078在荒漠旱生植物霸王适应逆境中的功能研究

The plant-specific NAC (NAM, ATAF1/2, and CUC2) transcription factors not only regulate the plant growth and development processes, but also play vital roles in the adaptation of plants to various kinds of abiotic stresses. Recently, despite much progress has been achieved on the stress resistance of NAC transcription factors in the glycophytes such as Arabidopsis, rice and wheat, little information is available about this family in the adversity-resistant eremophytes such as Zygophyllum xanthoxylum，which is super-resistant to drought and salt stress. In this project, by using Z. xanthoxylum as materials and taking ZxNAC in response to salt and osmotic stress (simulating the drought stress) as breakthrough points, subsequent experiments would focus on the molecular and physiology aspects: analyzing the transcript abundance of ZxNAC018 and ZxNAC078 under various stress conditons via real-time PCR and RNA in-situ hybridization techniques; measuring the physiological indexes and evaluating drought tolerance of transgenic Z. xanthoxylum based on the gene silencing of ZxNAC018 or ZxNAC078 using RNA interference (RNAi) technique; constructing ZxNAC018 and ZxNAC078 over-expression transgenic Arabidopsis respectively, then comparing the anti-adversity ability of ZxNAC018 and ZxNAC078 transgenic plants and wild-type Arabidopsis. These results would illustrate the functions of ZxNAC018 and ZxNAC078 in the adaptation of Z. xanthoxylum to stress. Furthermore, this will shed new light on the stress tolerance mechanism of Z. xanthoxylum, but also provide some important genetic resources and theoretical instructions for improving crops.

NAC作为植物特有的转录因子家族，不仅参与植物多个生长发育过程，而且在植物抗逆反应中发挥重要功能。目前，关于NAC转录因子调控植物抗逆性的研究主要以拟南芥、水稻、小麦等对干旱、高盐非常敏感的甜土植物为对象。我们前期已从抗逆能力极强的荒漠旱生植物霸王转录组数据中，发掘到2个受NaCl和渗透胁迫强烈诱导的NAC转录因子ZxNAC018和ZxNAC078。本项目拟在已有研究基础上，采用qPCR和RNA原位杂交技术进一步分析ZxNAC018和ZxNAC078响应高盐和渗透胁迫的表达模式；通过RNA干扰技术沉默它们在霸王中的表达，同时将其在拟南芥中超表达，评价干扰株系和超表达株系的耐盐抗旱能力，明确ZxNAC018和ZxNAC078在霸王适应逆境中的功能。以期进一步阐明霸王适应逆境的分子机理，为优良牧草和农作物抗逆分子育种提供重要的基因资源和理论依据。

本项目取得了以下主要进展和成果：（1）完成对渗透及盐处理条件下霸王根的转录组数据分析，筛选到大量在处理早期表达发生显著变化的转录因子。（2）系统分析了渗透及盐处理条件下ZxNAC035、ZxNAC083及ZxMYB40在霸王根中的表达模式。（3）成功构建了ZxNAC035、ZxNAC083和ZxMYB40两个转录本ZxMYB40α及ZxMYB40β的植物表达载体及RNA干扰载体。（4）获得转基因纯合拟南芥植株，并对ZxNAC035、ZxNAC083和ZxMYB40α、ZxMYB40β在植物抗旱耐盐过程中的功能进行分析，发现ZxNAC035、ZxNAC083和ZxMYB40β在植物抗旱耐盐过程中发挥正调控作用，而ZxMYB40α发挥负调控作用。（5）完成对盐处理条件下AtMYB40两个转录本AtMYB40.1及AtMYB40.2的表达模式分析。（6）完成AtMYB40.1及AtMYB40.2 CRIPSR/CAS9载体构建并获得基因编辑拟南芥植株。