生物能源作物柳枝稷苗期慢发育的机制研究

With the advantages of wide adaptability,strong stress resistance, rapid growth, higher biological yield, more cellulose, readily fermentable in ethanol production process and high energy output ratio, switchgrass has been regarded as a model bio-energy crop to replace the food crops for bio-ethanol production in the world.In mean time, because of switchgrass with other advantages including the developed roots, vigorous tillerings, high tolerance to drought and barren,strong wind-break and sand-fixation function, good ability to growing in field margins and desertified soil,it also has been considered as an ideal plant to soil and water conservation,desert virescence and prairie vegetation.The seed is often to be used in switchgrass reproduction at now. The bottleneck problem of switchgrass extension in big scale is the seedling from sprouting seed developed slowly in seedling stage and that lead to lowly compete to field weeds,badly tolerate to stress. The planting area,range and scale of switchgrass were restricted greatly because of the disadvantageous character. In our preliminary research, we have set up a rapid reproduction system of the artificial spike buds in switchgrass.In this project, we will utilize the mutant from artificial spike buds that induced mutation by EMS as the research material, and will analyze the formation pattern and biological mechanism of seedling slow development by using cytological, physiological, biochemical and molecular biological methods. From this research we expect to understand the mechanism of seedling slow development in switchgras seedling stage. In same time, this research project will contribute to the regulation technology system developed and the breeding indexs confirmed for improvement to the disadvantageous character.The results will promte switchgrass extension in certain degree and give some references for other crops or other characters research.

柳枝稷因其适应性广，抗逆性强，生长迅速，生物学产量高，富含纤维素，在乙醇生产过程中易降解且产率高，被国际上确定为替代谷类生产燃料乙醇的模式生物能源作物。柳枝稷根系发达，分蘖旺盛，耐旱耐瘠薄，防风固沙能力强，可利用边缘耕地和荒漠化土壤，也是水土保持、沙漠绿化和草原植被的理想植物。柳枝稷主要利用种子繁殖，而建苗困难（苗期慢发育）导致种子萌发幼苗对田间杂草的竞争力低下及对不良环境的耐受性偏差，严重影响了其种植的区域、范围及规模化发展，是限制柳枝稷大面积推广的瓶颈因素。本申请项目在前期建立的柳枝稷人工穗芽快繁体系的基础上，以经EMS诱导人工穗芽创制的突变体为材料，拟分别从细胞学、生理学及分子生物学层次上剖析苗期慢发育的形成规律，揭示苗期慢发育的生物学机制，并以期初步建立人工调控的技术体系及为育种筛选确定指标参数。研究结果对柳枝稷的推广种植具有推动作用，对其它作物及其性状的机制解析也有一定理论参考。

柳枝稷因其适应性广，抗逆性强，生长迅速，生物学产量高，富含纤维素，在乙醇生产过程中易降解且产率高，被国际上确定为替代谷类生产燃料乙醇的模式生物能源作物。柳枝稷根系发达，分蘖旺盛，耐旱耐瘠薄，防风固沙能力强，可利用边缘耕地和荒漠化土壤，也是水土保持、沙漠绿化和草原植被的理想植物。柳枝稷主要利用种子繁殖，而建苗困难（苗期慢发育）导致种子萌发幼苗对田间杂草的竞争力低下及对不良环境的耐受性偏差，严重影响了其种植的区域、范围及规模化发展，是限制柳枝稷大面积推广的瓶颈因素之一。本项目在前期建立的柳枝稷人工穗芽快繁体系的基础上，以经EMS诱导人工穗芽创制的突变体为材料，分别从细胞学、生理学及分子生物学层次对苗期慢发育的形成规律进行了研究，结果发现：柳枝稷苗期慢发育的细胞学机制可能为苗期根部维管组织和凯氏带发育缓慢，茎部维管组织和薄壁细胞发育延迟，以及叶片运动细胞发育较差、叶肉细胞叶绿体膜结构的改变和维管束鞘细胞线粒体的数目的减少所致。其生理学机制可能为慢发育苗根系欠发达，不能为地上部分提供充足的水分和营养；慢发育苗ABA含量相对较高，前期GSH含量、中期GA含量及后期IAA/ZR比值较低，不利于根系发育和植株生长。通过对快发育苗和慢发育苗转录组测序结果分析发现，慢发育的分子生物学机制可能为 GAs生物合成的差异、生物钟对光照和温度响应的差异、植物生长能量分配的差异、菌根形成的差异导致了柳枝稷不同的苗期发育速率差异。根据苗期慢发育机制的细胞学和生理学研究结果，结合柳枝稷的常规育种实践，幼苗根系是否发达尤其是根的长短、根的数目可作为鉴定苗期快慢发育的较为简便易行的育种指标之一。由于柳枝稷苗期慢发育涉及生长激素、光温响应、能量分配、菌根形成等诸多因素影响，结合项目具体实际，初步研究了丛枝菌根真菌对柳枝稷苗期慢发育的调控技术。项目研究结果对柳枝稷的推广种植具有推动作用，对其它作物及其性状的机制解析也有一定理论参考。

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