玉米-辣椒间作系统丛枝菌根真菌群落分异特征与抑病机制研究

Although intercropping of chili pepper with maize can reduce the chili pepper blight caused by Phytophthora capsici Leonian, the role of arbuscular mycorrhizal (AM) fungi in coordinating nutrient utilization and controlling chili pepper blight, as well as their distribution pattern in such intercropping systems have not been verified. In this project, firstly, a field experiment will be established to investigate effects of intercropping of chili pepper with maize on the land equivalent ratio (LER), the chili pepper blight, and the diversity and distribution pattern of AM fungal community as revealed by pyrosequencing and real-time PCR, and then analyze the relationship between AM fungal community succession, and the levels of both fertilization and blight suppression. Secondly, the dominant species of AM fungus will be isolated, identified, propagated, and further investigated for the roles of AM fungi, notably mycorrhizal hyphae, in coordinating the competitive processes between chili pepper and maize during nutrient absorption via a greenhouse experiment using the uncrossed-root method. Finally, another greenhouse experiment will be carried out to study the relative contribution and major pathway of AM fungi in reducing chili pepper blight in this intercropping system, including changes in root morphological characteristics, root exudates, and leaf enzymatic activities as detected by micro-CT scanning technology, high performance liquid chromatography (HPLC) and enzyme linked immunosorbent assay (ELISA). The results to be generated would be very valuable in providing a scientific basis for deepening AM fungal function in intercropping systems, which in turn would promote the healthy development of chili pepper production.

间作玉米对辣椒疫霉菌引起的辣椒疫病具有防控效果，但丛枝菌根（AM）真菌在该间作系统中的分布规律及其在间作作物养分竞争与辣椒疫病阻抑过程所发挥的作用目前尚不清楚。本项目拟通过田间小区试验研究玉米-辣椒间作模式的土地利用效率及对辣椒疫病的控制效果，并运用高通量测序与定量PCR技术解析间作玉米对AM真菌多样性及分布规律的影响，分析AM真菌群落演替与施肥水平及辣椒疫病控制效果之间的联系；然后从间作土壤中分离优势AM真菌并鉴定扩繁，在温室盆栽试验中采用隔根方式评估玉米-辣椒间作系统中AM真菌特别是“菌丝交流效应”在两种作物养分吸收与竞争过程中的协调功能；最后借助微CT扫描、高效液相色谱与酶联免疫等技术检测辣椒根系形态、分泌物及叶片酶活的响应特征，阐释间作系统中AM真菌对控制辣椒疫病的相对贡献与作用途径。通过本项目的研究，以期为深化对间作系统中AM真菌功能的认识以及推进辣椒产业的健康发展提供科学依据。

间作玉米对由辣椒疫霉引起的辣椒疫病具有防控效果，但丛枝菌根（AM）真菌对间作的响应及其在作物种间竞争和辣椒疫病防治过程所发挥的作用目前尚不清楚。本项目通过田间小区试验比较了等行距、等垄宽、等垄宽增肥等三种间作模式对两种作物生长及辣椒疫病防控的影响差异，发现间作改变辣椒根际AM真菌群落组成，但不同处理AM真菌群落结构分异不明显；其中等垄宽间作较等行距间作在提高AM真菌侵染率、防控辣椒疫病和保障经济产量上更具优势，且AM真菌侵染率变化与病害防控效果之间存在明显的联动效应；增肥能提高辣椒根际AM真菌多样性并进一步增强其对辣椒根系的侵染，但没有增产效果和应用价值。在温室盆栽试验中，采用自制根箱解析AM真菌特别是“菌丝交流效应”在两种作物养分吸收与竞争过程中的协调功能，发现AM真菌菌丝网络的建立增强了其对两种作物根系的侵染，通过提高玉米室土壤磷酸酶活性进而从该室吸收较多的磷，又通过改善磷向辣椒的分配从而提高辣椒的果实产量，致使辣椒对玉米的磷竞争性能增强；最后在土壤灭菌和重新接种辣椒疫霉条件下鉴别间作玉米和接种AM真菌对防治辣椒疫病的影响，发现间作玉米通过构建和发挥AM真菌菌丝网络功能促进辣椒植株对磷、钾的吸收进而增强其对辣椒疫病的防控效果，明晰了间作系统中AM真菌对控制辣椒疫病的相对贡献与作用途径。通过项目研究和结果凝练，可为深化对间作系统中AM真菌功能的认识及推进辣椒产业的健康发展提供科学依据。