【作者】 王宇；

【导师】 石志琦； 陈健；

【作者基本信息】 南京农业大学 ， 农业硕士（专业学位）， 2020， 硕士

【摘要】 水稻是我国重要的粮食作物。随着人口快速增长,稻米需求量逐渐提升。而水稻大面积种植过程中亦出现了一系列农业生产问题,其中,镉胁迫与稻瘟病较为突出。土壤中过量镉元素可抑制水稻生长,并在水稻中富集,造成食品安全隐患。水稻稻瘟病是由稻瘟菌(Magnaporthe oyrzae)引起的一种毁灭性病害,水稻在整个生育期均可患病,造成水稻大面积减产。针对这两个生产问题的防控措施研究一直备受关注。麝香草酚(Thymol)作为一种植物源天然单萜酚,具备抑菌、抗氧化等生物活性,已在医药和食品保鲜领域广泛应用。基于本实验室前期首次发现麝香草酚在农业中的应用潜力,本文研究了麝香草酚对水稻镉胁迫和镉吸收的缓解效果,以及对稻瘟病的防治效果。主要结果如下:1.麝香草酚可以有效缓解镉胁迫对水稻幼苗地上部的伤害,并可以减少镉元素在水稻体内的积累。水培实验结果显示:麝香草酚预处理水稻植株后,水稻对镉胁迫(CdCl2处理)的抵抗能力明显增强,表现为地上部恢复生长、叶绿素含量增加。麝香草酚可显著缓解镉胁迫导致的水稻叶片氧化损伤效应,表现为活性氧含量下降和氧化损伤程度降低。这可能源自于麝香草酚对水稻叶片抗氧化系统(APX,抗坏血酸过氧化物酶;CAT,过氧化氢酶)被激活,从而有效清除过量累积的活性氧。盆栽实验中,将水稻种植于含镉土壤中完成一个完整的生长期,并在孕穗期喷施麝香草酚。与对照相比较,施用麝香草酚可显著降低水稻旗叶与穗茎中的镉含量。这说明麝香草酚在调控水稻镉累积方面具备一定的应用潜力。2.麝香草酚可抑制稻瘟菌生长及其对水稻的侵染。使用含麝香草酚的培养基培养稻瘟菌,测定菌丝的各项生理指标。结果表明:麝香草酚可以显著抑制稻瘟菌菌丝的生长,并呈现浓度效应,EC50值为38.02 μg/mL。麝香草酚可导致稻瘟菌菌丝细胞膜损伤和细胞死亡。使用麝香草酚处理感染稻瘟菌的水稻幼苗,可有效阻止稻瘟菌在水稻叶片上的侵染,同时可有效改善水稻叶片的生理状态,包括叶绿素含量、维生素C含量、总蛋白含量显著升高。这为麝香草酚可能应用防治水稻稻瘟病提供了一定的理论基础。综上,本文发现了植物源天然化合物麝香草酚在调控水稻抗非生物胁迫(如:镉)和生物胁迫(如:稻瘟病)方面的生物活性,为后期将麝香草酚在农业中的应用开发和作用机制研究提供了一定的科学基础。更多还原

【Abstract】 Rice is an important food crop in China.With the rapid growth of population,the demand for rice is gradually increasing.A series of agricultural production problems also appeared in the process of large-scale rice planting,among which cadmium stress and rice blast were more prominent.Excessive cadmium in the soil can inhibit the growth of rice and accumulate in rice,which leads to food safety risks.Rice blast is a devastating disease caused by Magnaporthe oryzae.Rice can be affected in the whole growth period,resulting in large-scale yield reduction.The research on the prevention and control measures for these two production problems has been concerned.Thymol,as a natural monoterpenol from plants,has been widely used in the fields of medicine and food preservation due to its antimicrobial and antioxidant activities.Based on the discovery of the potential application of thymol in agriculture in the early stage of our laboratory,this paper studied the mitigation effect of thymol on cadmium stress and cadmium absorption in rice,as well as the control effect on rice blast.The main results are as follows:1.Thymol can effectively alleviate the damage of cadmium stress on the shoot of rice seedlings and reduce the accumulation of cadmium in rice.The results of hydroponics experiment showed that the resistance of rice to cadmium stress(CdCl2 treatment)was significantly enhanced after pretreated with thymol,which showed that the growth of shoot was restored and the content of chlorophyll was increased.Thymol can significantly alleviate the oxidative damage of rice leaves caused by cadmium stress,which is manifested by the decrease of active oxygen content and the degree of oxidative damage.This can be attributed to the activation of thymol on the antioxidant system(APX,ascorbic acid peroxidase;cat,catalase)of rice leaves,so as to effectively eliminate the excessive accumulation of active oxygen.In the pot experiment,rice was planted in cadmium bearing soil to complete a complete growth period,and thymol was sprayed in booting stage.Compared with the control,the application of thymol can significantly reduce the content of cadmium in flag leaf and spike stem of rice.This indicates that thymol has a potential application in regulating cadmium accumulation in rice.2.Thymol can inhibit the growth of Magnaporthe oyrzae and its infection on rice.The medium containing thymol was used to culture Magnaporthe oyrzae and the physiological indexes of mycelia were determined.The results showed that thymol could significantly inhibit the growth of Magnaporthe oyrzae mycelia,and the EC50 value was 38.02 μg/ml.Thymol can cause cell membrane damage and cell death of Magnaporthe oyrzae.Treatment of rice seedlings infected with Magnaporthe oyrzae with thymol can effectively prevent the infection of Magnaporthe oyrzae on rice leaves,and can effectively improve the physiological status of rice leaves,including the significant increase of chlorophyll content,vitamin C content and total protein content.This provides a theoretical basis for the application of thymol in the control of rice blast.In conclusion,this paper found that the plant-derived natural compound thymol can regulate the biological activity of rice against to abiotic stress(such as cadmium)and biological stress(such as rice blast),which provides a scientific basis for the later application and development of thymol in agriculture and the study of its mechanism of action.更多还原