促生真菌M23促进铁皮石斛生长的碳代谢调控机制研究

Dendrobium officinale is a rare and endangered medicinal plant, which belongs to Orchidaceae and contains huge market demand. At present, artificial cultivation mainly relies on tissue culture technology, but the problems of high planting cost and uneven quality remain to be solved. In the wild, the growth and development of Dendrobium officinale are closely related to symbiotic fungi. Thus, the application of mycorrhizal cultivation technology will help to control planting costs and ensure quality. Our previous study found that the PGPF M23 was significantly better than other strains in enhancing plant growth in field trials, especially to promote dry matter accumulation. However, the research on its growth-promoting mechanism is still very limited. Since more than 50% of the plant dry matter is carbon, it is considered that the strain exerts a promoting effect by affecting the carbon metabolism pathway.To this end, the project mainly conducts the following research: ① using dual culture systems, cell biology and analytical chemistry techniques to clarify the interaction characteristics between this stain and Dendrobium officinale; ② through metabolomics, 13C labeling and nuclear magnetic resonance spectroscopy, analyzing two pathways of carbon absorption from fungal absorption and plant photosynthesis, the differential metabolites after symbiosis were identified, the regulation mechanism of carbon metabolism in symbiosis were revealed. The implementation of this project will provide detailed data support for the study of symbiotic interactions in nutrient metabolism and transport, and provide theoretical guidance for the mycorrhizal cultivation techniques of Dendrobium officinale.

铁皮石斛是珍稀濒危兰科药用植物，蕴含巨大的市场需求。现阶段主要依靠组织培养技术对其进行繁殖，但种植成本高、质量参差不齐等问题仍有待解决。野生铁皮石斛的生长发育与共生真菌息息相关。应用菌根栽培技术将有利于控制成本、保障质量。本课题组前期研究发现，在田间试验促生菌株M23的促生长作用显著优于其他菌株，尤其是促进干物质积累。但对其机制的研究仍非常有限。由于植物干物质50%以上由碳元素组成，故认为该菌株通过影响碳代谢途径发挥促生作用。为此，本项目主要开展以下研究：① 利用双重培养体系、细胞生物学等技术，明确活性菌株与铁皮石斛的互作特征；② 通过代谢组学、13C标记和核磁共振波谱分析等技术，明确共生后的差异代谢产物，从真菌吸收和植物光合两个碳源营养物质获得途径揭示共生体内碳代谢的调控机制。本项目的开展为共生互作的营养物质代谢与转运研究提供了详实地数据支撑，并为铁皮石斛菌根栽培提供了理论指导。

铁皮石斛是我国珍稀濒危兰科药用植物，市场潜力大。兰科植物人工栽培成本高，促进兰科植物生长发育的真菌资源有待开发和应用。本项目通过①与铁皮石斛常见促生菌株的促生效果及②与常见促生菌株混合接种后的促生效果相比较，明确真菌Mycena sp. M23在模拟田间种植环境中所发挥促生效果，及该真菌-植物相互作用在细胞和亚细胞结构变化特征的独特性，以及发现该菌株促进铁皮石斛生长的物质基础。重要结果如下：1）菌株Mycena sp.单独接种或混合接种均可持久、显著促进植株生长，且提高茎多糖含量的作用较菌株Tulasnella sp.更稳定，是未接菌对照组的2.8倍。2）菌株Mycena sp.与铁皮石斛幼苗根的互作结构，与在内皮层细胞形成大量菌丝团的兰科菌根真菌Tulasnella sp.不同。菌株Mycena sp.的大量菌丝包裹在根最外层，皮层薄壁细胞内有颗粒物质积累。3）与该菌株共生可显著影响植物对大量元素的吸收与利用，但并未改变原植物光合自养的营养类型，且光合作用产物优先被标记。上述研究结果对阐明菌株Mycena sp. M23促进铁皮石斛生长的机制有重要理论意义，对其独特促生作用的揭示，增加植物-真菌共生多样性案例，为该菌株在更广泛的种植产业中应用奠定理论基础。