外源Ca2+对青藏高原药用植物独一味、甘肃贝母幼苗抗冻性作用机理研究

It aims at the serious problem and actuality that the temperature is low in the adaptive environment for Medicinal Plant such as Tibet Lamiophlomis rotate and Fritillaria cirrhosa which seedlings are so sensitive that few can live through the winter and re-green, turning out failure in wild recovery and domestication resulting in exhausted resources and big gap in the medicinal source in Tibetan area. According to the theory that exogenous calcium ion can transmit the signal as the second messenger in plant under low temperature, different concentrations of dichloride calcium are sprayed over the plant in different stages of growth and development, compared with the control without spray. After lived through the winter and greened, the root vigour, physiological and chemical indicators (stable state of biomembrane, ability in osmotic modulation, protein stability, lethal temperature, lipid peroxidation, antioxidation system and so on) and cold-induced proteins are mensurated to find the scientific evidence for the exogenous calcium to affect the stress resistance of the seedlings, exploring the effective mechanism of exogenous calcium on overwintering and greening of the plant seedlings, finally setting up and consummating the theory and method of wildness revival and domesticate cultivation, ameliorating the stress resistance of the plant seedlings, protecting the ecological environment and improving the sustainable development for the plants in the Tibet area.

针对我国青藏高原药用植物野生抚育和驯化栽培中幼苗抗冻性差，适生环境温度低，生长缓慢，冬前生长量小，冬季大量死亡，越冬成活率低的严重问题，选择独一味和甘肃贝母为典型试验植物，依据Ca2+在植物低温信号传导中可作为第二信使的原理，利用不同浓度CaCl2在越冬前不同时期喷施独一味幼苗，以不喷施为对照，然后测定越冬苗形态解剖结构、生理生化特性（根系活力，膜稳态性、渗透调节机能、蛋白质稳定性、半致死温度、膜质过氧化程度、抗氧化系统等）及抗冻蛋白表达等指标的变化差异，越冬后测定越冬成活率、生长动态和药材产量，旨在揭示外源Ca2+对青藏高原药用植物幼苗抗冻性的作用机理，建立和完善独一味和甘肃贝母野生抚育和驯化栽培的技术及理论体系，探寻提高青藏高原药用植物幼苗抗冻性的技术依据，以期有效改善其幼苗的抗冻性，缓解极端低温胁迫对越冬幼苗的伤害，提高越冬成活率，促进青藏高原药用植物资源的可持续化发展。

针对我国青藏高原药用植物野生抚育和驯化栽培中幼苗抗冻性差，适生环境温度低，生长缓慢，冬前生长量小，冬季大量死亡，越冬成活率低的严重问题，选择独一味和甘肃贝母为典型试验植物，依据Ca2+在植物低温信号传导中可作为第二信使的原理，利用不同浓度CaCl2在越冬前不同时期喷施独一味幼苗，以不喷施为对照，然后测定越冬苗形态解剖结构、生理生化特性（根系活力，膜稳态性、渗透调节机能、蛋白质稳定性、半致死温度、膜质过氧化程度、抗氧化系统等）及抗冻蛋白表达等指标的变化差异，越冬后测定越冬成活率、生长动态和药材产量，旨在揭示外源Ca2+对青藏高原药用植物幼苗抗冻性的作用机理，建立和完善独一味和甘肃贝母野生抚育和驯化栽培的技术及理论体系。研究结果表明，独一味对低温具有较强的耐受性，甘肃贝母对低温有一定的适应性，但两植物幼苗均极不耐低温，对-4～4℃低温的敏感性因植株发育阶段和器官的不同而异，甘肃贝母以叶片POD与CAT活性协同清楚多余自由基发挥抗氧化作用，独一味参与抗逆的抗氧化酶类更多，抗逆性更强。适宜浓度外源Ca2+均可有效激活独一味和甘肃贝母抗氧化酶系统，保护细胞膜免受损伤，提高植株的抗寒性。提早返青期，延后倒苗期，从而延长生长，促进植株生长发育，增大年生长量，甘肃贝母鳞茎鲜重较CK显著增加了31.58%。喷施CaCl2对根际土壤环境产生一定影响，适宜Ca2+浓度可适当降低土壤电导率，增加土壤蛋白酶和蔗糖酶活性，对5～10cm土层土壤影响更为明显。以上说明适宜浓度外源钙可通过改变土壤内部环境，并对甘肃贝母和独一味起到生理调控作用，提高抗冻性，延长生长期，增加年生长量。通过本项目研究，探寻出提高青藏高原药用植物幼苗抗冻性的技术依据，有效改善了幼苗的抗冻性，缓解了极端低温胁迫对越冬幼苗的伤害，提高越冬成活率，延长了生长期，项目成果的应用将促进青藏高原药用植物资源的可持续化发展。