苎麻连作障碍发生规律分析及其相关基因的筛选

Ramie is a very important economic crop of china, and a good forage plant source of protein. As the symptoms of slow growth, failure stump obstacles arose after several years of continuous cropping, the yield of ramie was reduced severely, then influenced economic benefits. As a result, peasants are unwilling to plant ramie. It is really bad for the development of ramie industry. the study of occurrence regularity and screening of the gene related to continuous cropping obstacle had not been reported yet at home and abroad. our group have been the first studied that time of continuous cropping obstacle on ramie for recently many years, confirmed that the continuous cropping obstacle effect in 8 years soil was significantly more than that of other tested soil. This study will analyze the occurrence regularity of continuous cropping obstacle on ramie with field investigation and pot simulations method, constructing the forward and reverse subtractive cDNA libraries of continuous cropping ramie use the suppression subtractive hybridization (SSH) technique, screening genes about continuous cropping obstacle on ramie by PCR to detect the positive clones which would be sequenced and analyzing by bioinformatics, verified occurrence regularity of continuous cropping obstacle on ramie ,reduce the affect of growth and development, yield and quality come from continuous cropping obstacles on ramie, to achieve the sustainable development of the ramie. This study will analyze several key genes in response to replant problem, which not only will be lay the foundation for revealing the molecular mechanism of continuous cropping obstacle on ramie, but also provide a theoretical basis and molecular mechanism for better solve the problems of defeat stump on ramie.

苎麻是我国极具特色的经济作物，还是很好的饲用植物蛋白质来源。但连作数年后苎麻出现生长缓慢、败蔸等障碍现象，严重降低了产量和经济效益，影响麻农种麻积极性。关于苎麻连作障碍发生规律及连作障碍基因筛选的研究迄今国内外尚无报道。本课题组通过近几年的研究首次探明了苎麻连作障碍发生时期的主要症状，明确了苎麻连作8年及以上麻园连作障碍发生严重，本项目采用大田调查和盆栽模拟试验相结合的方法分析苎麻连作障碍发生规律，在连作障碍发生时期利用抑制性消减杂交方法构建正茬、重茬苎麻正反向cDNA文库，经EST测序、生物信息学分析筛选苎麻连作障碍相关的基因，明确连作障碍发生规律、降低连作障碍因子对苎麻生长发育及产量品质的影响，实现苎麻的可持续发展。本项目筛选苎麻连作障碍的关键基因，为揭示苎麻连作障碍的分子机制奠定基础，为更好的解决苎麻连作带来的败蔸问题提供理论依据和分子机理。

摘要：苎麻连作数年后苎麻出现生长缓慢、败蔸等障碍现象，严重降低了产量和经济效益，影响麻农种麻积极性。关于苎麻连作障碍因子及其相关基因的研究较少，为了探明苎麻连作障碍发生规律及筛选相关的基因，本项目首先调查了不同地区连作苎麻大田产量性状指标，分析表明连作8年的苎麻障碍现象严重发生，4年的变化不明显，1年的不存在障碍现象。在大田调查的基础上通过盆栽模拟试验对不同连作年限苎麻的地上部和地上部表型数据的分析，明确苎麻连作障碍发生的主要症状。分析连作苎麻根际分泌物，根际微生物及根腐线虫对苎麻生长的影响，并设置盆栽试验，发现根腐线虫害是导致苎麻连作障碍的重要因子。转录组测序分析了根腐线虫感染苎麻的全基因组表达谱，一共识别777个受根腐线虫害诱导表达的基因，其中592个基因是上调表达，185个基因是下调表达。差异基因的KEGG代谢通路分析发现当植株受到线虫侵染时有61条代谢通路受到影响，其中有三种途径：苯丙氨酸代谢，类胡萝卜素和苯丙生物合成受到严重影响。基于筛选出来的表达差异基因，我们分析了这些基因根腐线虫逆境下的表达水平，发现有45个基因受根腐线虫感染诱导表达，这些基因分布在MYB、AP2/ERF、bZIP、HD-ZIP和COL等五大基因家族，其中MYB家族基因最多有23个基因。