恩施堇叶碎米荠硒耐受与富集的生理遗传机制研究

Cardamine,a selenium accumulation novel plant resources to be found in the selenium-mine drainage area in Yutangba of Enshi, was discovered in recent years.Our group selected Cardamine violifolia O.E.Schulz of selenium hyperaccumulator from wild species in the above area. The selenium content in dry leaves of Cardamine violifolia can be as high as 2156.00mg/kg(dry mass), when selenium was supplied through leaves and roots. This data exceed international standards of selenium hyperaccumulators (1000 mg / kg(dry mass)), it fill in the blank of which selenium hyperaccumulator had not been found so far in our country. Selenium is an essential element ,it is a great significance for human health to deepen the study of the formation mechanism of plant organic selenium source. We intend to reveal some typical characteristics, such as morphology and anatomy, related metabolic enzymes activity and growth and development, when Cardamine violifolia, a seleniumhyperaccumulator, is in response to the effects of selenium. We also scheme to clear some analysis items, Including selenium tolerance threshold, the level and distribution of selenium, as well as the main categories of organic selenium. We propose to disclose the new candidate genes and metabolic pathways associated with selenium tolerance and enrichment using transcriptome technology, also to search key genes and to explore the function of genes.We apply for the project to investigate the physiological and genetic mechanisms of selenium tolerance and hyperaccumulation in Cardamine violifolia thoroughly，This scheme has important theoretical and practical significance for the development and utilization of scarce resources in selenium hyperaccumulation plant of our country.

恩施鱼塘坝富硒矿溪流区域的碎米荠是近年新发现的富硒植物资源。课题组从该区域的野生材料中筛选到聚硒堇叶碎米荠（Cardamine violifolia O. E. Schulz），人工补硒培养该植株叶干样硒含量最高可达到2156.00mg/kg，超过了硒超富集植物国际标准（1000 mg/ kg），填补了我国未曾发现此类植物的空白。硒是人体必需元素，深化植物有机硒源的生成机制研究对人类健康意义重大。我们计划揭示富硒堇叶碎米荠响应硒效应的形态解剖、代谢关联酶活性、生长发育的典型特征；明确该植物的硒耐受阈值，含硒水平与分布和有机硒主要类别；采用转录组测序技术揭示硒耐受与富集关联的新代谢途径和候选基因，克隆关键基因，探查基因功能；申请立项深入研究堇叶碎米荠硒耐受与硒超富集的生理遗传机制，对我国稀有的富硒植物资源的开发与利用具有重要理论和实践意义。

硒是人和动物必需元素之一，探索高硒植物源堇叶碎米荠耐硒机制，有助于利用现代农业栽培手段进行富硒标准化种植推广应用。本项目初期通过堇叶碎米荠种子发芽、硒源筛选、施硒方式、栽培方式对比试验，筛选出堇叶碎米荠硒酸钠基质根施栽培方式获得可利用部分硒累积量最高。通过高通量测序技术结果分析，堇叶碎米荠根系分泌有机物使土壤微生物群落多样性丰富，存在大量的微生物类群，其中变形菌门(Proteobacteria)即为优势菌门，有助于对根系对硒的吸收。中期对堇叶碎米荠形态解剖学和关联酶学分析，揭示了其耐硒储硒功能，叶片和根皮层和皮下组织胞间Φ增厚，不定根系发达，成熟的主根具有带周皮的二级结构，有利于根和叶吸收储存硒，且其在硒胁迫应急反应中GSH、CAT和GSH-Px起关键作用。后期根据转录组分析和基因克隆与功能鉴定，揭示了硒富集的关联基因GO、COG、KEGG和代谢途径，高硒植物源堇叶碎米荠耐硒机制研究，将有助于“世界硒都（恩施）”对其资源化开发与利用。