伴生小麦提高西瓜枯萎病抗性的化感作用机理

Soil sickness has become a constraint of the sustainable development of facility agriculture. Watermelon is one of the crops that could severely suffer soil sickness, and Fusarium is one of the causes of its soil sickness. Our previous study showed that, as a companion crop, wheat could suppress the Fusarium wilt of watermelon. However, the mechanism is still unclear. Based on the screened wheat varieties with Fusarium wilt-suppressing characters, this project will focus on: (1) isolation and characterization of the allelochemicals in wheat root exudates that suppress Fusarium oxysporum f.sp. niveum; and then detecting the concentration and their dynamics of these allelochemicals in the soil; (2) studying the allelopathy effects of accompanying wheat, wheat root exudates and its allelochemicals on soil microbial communities with Miseq sequencing, PCR-DGGE, qPCR, clone library and Biolog methods; (3) revealing the relationship between the changes in soil microbial communities induced by wheat with the occurance of watermelon Fusarium wilt with plant-microbial feedback experiments. This project is expected to reveal the mechanism of how wheat could suppress Fusarium wilt of watermelon as a companion crop from the view of allelopathy, Overall, this study could provide theoretical foundation and technical support for the application of the wheat as a companion crop of watermelon and the reduction of the soil sickness in watermelon production.

连作障碍已成为制约设施园艺健康可持续发展的瓶颈问题，西瓜是最忌连作的作物之一。其枯萎病是连作障碍的主要因子。申请者发现，小麦伴生西瓜具有抑制西瓜枯萎病的作用，但机理不明。本项目在已筛选出的抑制西瓜枯萎病小麦品种基础上，（1）运用化感作用原理，分离鉴定小麦根系分泌物中抑制枯萎病菌的化感物质，明确其在土壤中的浓度变化；（2）采用Miseq高通量测序、PCR-DGGE、qPCR、克隆文库、Biolog等技术，研究伴生小麦、小麦根系分泌物及其化感物质对土壤微生物菌群的化感作用；（3）通过植物-微生物反馈试验揭示伴生小麦诱导的土壤微生物区系变化与枯萎病发生之间的关系。通过该研究试图探明伴生小麦提高西瓜枯萎病抗性的化感作用机理，为小麦伴生西瓜栽培模式的应用及其缓解西瓜连作障碍提供理论基础和技术支撑。也为相关研究提供参考。

西瓜是最忌连作的作物之一，其中枯萎病是西瓜连作障碍发生的主要因子。申请者发现，小麦伴生西瓜具有抑制西瓜枯萎病的作用，但机理不明。本项目在已筛选出抑制西瓜枯萎病的小麦品种的基础上，研究了伴生小麦缓解西瓜枯萎病的化感作用机理。主要结果如下：.1.小麦（D123）的根系分泌物显著抑制Fusarium oxysporum f. sp. niveum（FON）的生长，无论是伴生还是单作的小麦根系分泌物均可以有效降低西瓜枯萎病发病率。.2.分离、鉴定出小麦根系分泌物中抑制FON的化感物质主要是鞘氨醇类物质和对香豆酸；土壤中对香豆酸的浓度是0.036±0.01μmol /g鲜土；土壤中，外源植物鞘氨醇和对香豆酸在添加后2天降解速度较快，而添加后第四天降解速度趋于稳定，半衰期分别为1.97d和0.85d；.3.Miseq高通量测序和qPCR结果显示，外源添加小麦根系分泌物和抑菌物质植物鞘氨醇均增加了西瓜根际土壤中芽孢杆菌、放线菌、链霉菌、木霉菌、产DPAG、PRN和PCA的菌群丰度，降低了FON的丰度，改变了微生物群落多样性和群落组成，表明小麦根系分泌物中的抑菌物质在调控西瓜根际土壤微生物菌群中起了作用；.4.伴生小麦增加了西瓜根际细菌、假单胞菌、放线菌、链霉菌、木霉菌、产DPAG、PRN和PCA的菌群丰度，降低了真菌、芽孢杆菌、尖孢镰刀菌和FON的丰度；植物-土壤反馈实验表明伴生小麦可以通过影响西瓜根际土壤微生物菌群而减轻西瓜枯萎病的发生。.该研究为小麦伴生西瓜栽培模式的应用及其缓解西瓜连作障碍提供了理论基础和技术支撑。该项目共发表8篇论文，其中SCI文章6篇，培养研究生3名，其中毕业硕士1名，今年6月将毕业2名，其中博士、硕士各1名, 参加各种学术交流5 次，超额完成了项目指标。