元阳梯田水稻-稻瘟病菌互作对UV-B辐射响应的特征及机理研究

Yuanyang Terrace is a typical and representative paddy ecosystem with sustainability, in which the local traditional rice varieties have the characteristics of low incidence of rice blast. Some significant effects of UV-B radiation on the rice blast were observed under laboratory conditions. However, the effects and mechanisms of UV-B radiation on the rice blast under field conditions were poorly understand. In this project, some field experiments for 4 consecutive years were carried out to investigate the effects of enhanced UV-B radiation on a traditional rice variety Baijiaolaojing in Yuanyang Terrace. In these experiments, some indexes will be observed that including the index of rice blast, the growth and sporulation of Magnaporthe grisea, the morphology of rice leaves, the contents of disease-resistant material, the activity of defensive enzymes and the expression of coding gene. The aims included: (1) to discover the effects of UV-B radiation on the incidence of rice blast, the infection level of Magnaporthe grisea, the leaves morphology, physiology and molecular indicators related to disease resistance; (2) to understand the physiological and molecular characteristics of the interactions between rice and Magnaporthe grisea to UV-B radiation and the relationship with incidence of rice blast; (3) to explore the mechanisms in the effects of UV-B radiation on the interactions between rice and Magnaporthe grisea. This project would provide new knowledge about the change trends of the crops diseases to enhanced UV-B radiation in field conditions, and enrich the theory on the relationship between UV-B radiation and crop diseases.

元阳梯田传统水稻品种具有低稻瘟病发病率的特点，而外来引进品种稻瘟病发病率较高。UV-B辐射对室内水稻稻瘟病有显著影响，但大田条件下UV-B辐射对水稻稻瘟病的影响与机理的认识有限。项目以元阳梯田传统水稻品种白脚老粳为研究对象，模拟不同强度UV-B辐射增强，开展连续4年的大田试验，观测大田水稻稻瘟病的病情指数，稻瘟病菌的生长与产孢，水稻叶片的形态结构、抗病物质含量、防御酶活性及其编码基因表达等指标，分析UV-B辐射对大田稻瘟病发生、病菌侵染力、水稻叶片抗病形态结构、生理与分子的影响，研究元阳梯田水稻-稻瘟病菌互作对UV-B辐射响应的生理与分子特征，及其与稻瘟病发生的关系，探讨UV-B辐射影响元阳梯田水稻-稻瘟病菌互作的机理。为地表UV-B辐射增强情景下大田作物病害发生发展的规律与变化趋势提供新的认识，丰富UV-B辐射与作物病害发生相互关系的理论，具有重要的意义。

以元阳梯田稻田生态系统中水稻-稻瘟病菌互作体系为研究对象，分析该体系对UV-B辐射增强的响应特征及机理。连续4年原位种植传统水稻品种白脚老粳，研究不同程度的UV-B辐射增强（0、2.5、5.0和7.5 kJ·m-2）以及UV-B辐射（0、5.0 kJ·m-2）处理不同感病时期的水稻，对水稻-稻瘟病菌互作体系中水稻、稻瘟病菌以及稻瘟病发生的影响，根据UV-B 辐射增强对种植于元阳梯田的白脚老粳稻瘟病发生的影响规律，从稻瘟病菌致病性和水稻抗病性的角度分析水稻叶片稻瘟病菌、形态结构、抗病物质、抗病生理与分子等指标对UV-B 辐射的响应特征。经过3年的大田和盆栽试验研究，发现（1）UV-B辐射增强可以提高水稻的抗逆性，通过强化叶片形态结构减轻稻瘟病菌对水稻叶片的损伤，UV-B辐射诱导感病初期水稻叶片抗病相关酶活性显著提高（PAL，LOX,CHI,β-1，3葡聚糖酶），提高抗病基因表达（OsPAL，OsLOX，OsCHI）增加抗病相关物质含量（类黄酮，硅等）；（2）增加5.0kJ/m-2UV-B辐射辐射能显著抑制稻瘟病菌生长发育与致病基因表达（Chitinase, MGP1, MAGB, CPKA）；（3）UV-B辐射增强，改变了元阳梯田传统水稻与稻瘟病菌生存环境，在一定变化强度内，适当剂量的UV-B辐射能有效抑制病菌的致病力和提高水稻的抗病能力有效减少稻瘟病病害，为地表UV-B 辐射增强情景下大田作物病害发生发展的规律与变化趋势提供新的认识，丰富UV-B 辐射与作物病害发生相互关系的理论。该项目已发表论文10篇，培养博士生1人，硕士生4人。课题组人员参加了7次国际、国内学术会议。