紫花针茅-内生真菌共生体对根寄生危害的生理响应机制

Root hemiparasitic plant - Pedicularis kansuensis has become an indicative weed on degraded grassland of Qinghai-Tibet Plateau and patchy-distributed with Stipa purpurea, which are dominant grass species in this region. Previous researches indicated that endophyte occurrence of S. purpurea were almost 100% in Qinghai Plateau, meanwhile, S. purpurea have become important host of P. kansuensis. Mutualistic symbioses between Epichloë and grasses has been verified by many experimental evidences. To explore the physiological response mechanism of S. purpurea-Epichloë symbiosis were parasitized by P. kansuensis, growth, photosynthetic characteristic, protective enzymes activity, osmotic adjustment substances and phytohormone of endophyte-infected (E+) and endophyte-free (E-) plants were determined when S. purpurea was parasitized by P. kansuensis. The results will clarify the regulating physiological role of Epichloë on grasses that are parasitized by root-hemiparasitic plant, and try to reveal the physiological response mechanism of S. purpurea- Epichloë symbiosis that is parasitized by root-hemiparasitic plant. The aim of this research to provide scientific evidence to understand the essence of mutual relationship between Epichloë and grass, and effective utilize this special symbiosis.

根部半寄生植物-甘肃马先蒿是青藏高原退化草地主要滋生的毒杂草种类。前期研究发现，紫花针茅是甘肃马先蒿和Epichloë内生真菌共同的寄主，甘肃马先蒿寄生能抑制紫花针茅的生长，使紫花针茅处于一种胁迫环境；而Epichloë内生真菌与禾草间保持互利共生的关系，内生真菌能提高禾草对生物、非生物胁迫的抗性和耐受力。目前，禾草内生真菌共生体对根寄生危害的生理响应机制尚不清楚。本项目以甘肃马先蒿寄生的紫花针茅带菌（E+）、不带菌（E-）植株为研究对象，采用常规植物生理分析和植物组织解剖的方法，开展甘肃马先蒿不同寄生强度下E+、E-植株的生长、光合、保护性酶活性、渗透调节物质及植物激素含量变化的对比研究，探求内生真菌对根寄生危害禾草的生理调控作用，揭示紫花针茅-内生真菌共生体对根寄生危害的生理响应机制，为深入理解内生真菌与禾草共生关系的实质及有效地利用内生真菌-禾草共生体这一特殊的生物资源提供科学依据。

根部半寄生植物-甘肃马先蒿是青藏高原退化草地主要滋生的毒杂草种类。前期研究发现，紫花针茅是甘肃马先蒿和Epichloë内生真菌共同的寄主，甘肃马先蒿寄生能抑制紫花针茅的生长，使紫花针茅处于一种胁迫环境；而Epichloë内生真菌与禾草间保持互利共生的关系，内生真菌能提高禾草对生物、非生物胁迫的抗性和耐受力。目前，禾草内生真菌共生体对根寄生危害禾草的生理响应机制尚不清楚。本项目以甘肃马先蒿寄生的紫花针茅带菌（E+）、不带菌（E-）植株为研究对象，采用常规植物生理分析和植物组织解剖的方法，开展甘肃马先蒿不同寄生强度下E+、E-植株的生长、光合、保护性酶活性、渗透调节物质及植物激素含量变化的对比研究。研究发现内生真菌通过促进紫花针茅分蘖、增强光合作用、激活抗氧化酶活性、调节细胞膜透性、增强根系生长能力、调控促生长和逆境预警内源激素水平、改变生物碱含量和抑制根寄生植物根部形成途径增强紫花针茅对根寄生逆境的耐受能力。上述研究结果证实内生真菌可通过调控禾草体内生理过程对根寄生逆境做出响应，缓解根寄生植物对禾草的伤害，这将为深入理解内生真菌与禾草共生关系的实质及有效地利用内生真菌-禾草共生体对根寄生杂草生物防控提供科学依据。