生物能源作物柳枝稷苗期干旱胁迫记忆基因挖掘和功能解析

With the advantages of large biomass, rich cellulose, readily fermentable in ethanol production, non-encroach farmland, switchgrass (Panicum virgatum), a C4 grass belonging to the family of Gramineae, has been considered as a model bioenergy plant to replace food crops for bioethanol production all over the world. The robust roots give them the ability to survive in marginal field and other sophisticated environments, so it’s also the ideal plant for water-soil conservation, desert reclamation and grassland vegetation. However, switchgrass seedlings develop slowly and are susceptible to drought stress, which has gravely affected its plantation and economic benefits, and this problem has been the bottleneck factor for large-scale plantation. Drought stress memory genes were found in model plants in recent years, they can “remember” the last drought stress. When plant suffers water-deficit stress again, these genes response quickly to help plant acquire drought resistance. In the present study, we will analyze the responsive network of drought stress on physiological and transcriptional levels, explore drought stress memory genes, and uncover the functions of different kinds of drought stress memory genes and their correlation with drought resistance, plant hormones and DNA methylation. This study will establish the foundation for fine-improving drought resistance of seedlings and promote the large-scale plantation of switchgrass. The exploration and function analysis of different kinds of drought stress memory genes will catch people's attention to utilizing these special resources and provide strategies and references for the resistance breeding of other crops.

禾本科C4植物柳枝稷因生物量大，纤维素含量高，易降解产生乙醇，不与粮争地等特点，已被国际上确定为替代粮食生产燃料乙醇的模式生物能源作物。柳枝稷成株根系发达，适应性强，可利用边缘土地，也是水土保持、沙漠绿化和草原植被的理想作物。然而，其幼苗发育缓慢，易遭受干旱胁迫，严重影响其种植区域和经济效益，是规模化种植的瓶颈因素。干旱胁迫记忆基因是近年来在模式植物中发现的一类对干旱胁迫存在“记忆”的基因。当植物再次遭遇干旱时，这类基因迅速响应以使植物产生抗旱性。本项目拟从生理生化水平和转录水平剖析苗期柳枝稷对周期性干旱胁迫的响应网络，挖掘干旱胁迫记忆基因，解析不同类型记忆基因功能与抗旱性、植物激素以及DNA甲基化的关系，以期为定向精细改良幼苗抗旱性建立基础，推动柳枝稷规模化种植。不同类型干旱胁迫记忆基因的挖掘和功能分析，将会促进人们关注和开发利用这一特殊资源，为其他作物抗逆育种提供新的思路和依据。

柳枝稷因生物量大，纤维素含量高，易分解产生乙醇，可遗传转化等特点，已被认为是替代粮食生产燃料乙醇的模式生物能源作物。本项目从生理生化水平和转录水平剖析了柳枝稷苗期对周期性干旱胁迫的响应网络，鉴定了干旱胁迫记忆基因741个，它们主要参与苯丙烷代谢、糖与淀粉代谢、植物激素信号转导、等途径。具体结合生理数据分析显示，柳枝稷改变了代谢方式以应对第二次失水胁迫，主要包括：提高ABA合成、积累及信号转导，调节JA合成与积累，合成脯氨酸、水苏糖、海藻糖等渗透保护物质，改善光合系统、糖酵解、TCA循环等能量代谢。HPLC-MS分析发现，ABA在D1和D2中均显著积累，JA在D1中积累，在D2中显著减少。对柳枝稷、拟南芥和玉米中的胁迫记忆基因进行分析发现，各物种之间存在特异性与保守性。通过转基因手段，初步解析了两种不同类型记忆基因功能与抗旱性、植物激素的响应关系，为定向精细改良幼苗抗旱性建立了一定理论基础。