小麦条锈病越夏地区传播规律的分子定量检测

Wheat stripe rust, caused by fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is devastating diseases in China. The major inoculum source of the pathogen causing regional epidemics was considered from the western mountainous areas where the pathogen can oversummer to complete its life cycle. Gansu Province is considered to be main region where the oversummering inoculum could be significantly accumulated. The pathogen dispersal within this region is still unclear and the information on the location and development of initial inoculum is vital to manage disease epidemics at regional scale. This study will emphasize on research to determine the pathogen pathway in Gansu Province as possible dispersal directions and development of inoculum. This anticipated study is going to involve two projects: 1) to quantify the urediniospores of Pst in the air to estimate potential of inoculum density in the air and possible direction of pathogen dispersal; and 2) using molecular population genetic approaches and newly developed analysis methods to determine the pathogen migration rates and dispersal pathways. This study plans to set up 5-6 spore traps in Longdong and Longnan of Gansu to monitor the annual dynamics of urediniospores of Puccinia striiformis in the air. The real-time PCR assay developed in this study will be applied to rapidly and accurately quantify the spore density in the air periodically. Weather data, as well as the field disease data in the studied areas will be collected. Intensive data analysis will be conducted to determine how the spore density data, in combination with future weather data, can be used to estimate the possible dispersal directions and the overall quantity of oversummering inoculum in relation to the potential risk of autumn disease development. The pathway of pathogen dispersal in these two regions of Gansu Province will be also intensively studied with the methods of molecular population genetics. The oversummering diseased leaves will be collected from fields at different altitudes to obtain the Pst populations. AFLP and SSR makers will be applied to generate molecular datasets for the collected samples. Indirect and direct methods using molecular data, will be applied to infer the pathogen dispersal pathways in Gansu Province. Intensive analysis will also include testing the hypothesis on asymmetric migration between any two interested locations by using likelihood-ratio tests and Bayesian statistics. The probability of asymmetric dispersal will be determined using migration rate calculated with above methods, thus, possible pathogen dispersal pathogen, as well as the possible source locations where very initial inoculum could be generated will be determined. This research will provide important information on inoculum initiation and its possible development in Gansu. The information will be used to estimate the potential disease inoculum density affecting regional epidemics of wheat stripe rust in China.

本研究通过完善和运用定量测定空气中的孢子浓度和分子群体遗传学手段测定传播路线和速率两种研究途径，以甘肃不同海拔越夏区为基地，集中开展小麦条锈病菌源初始源和传播路径和速率的研究。定量分析空气中孢子浓度监测越夏菌量动态，估计越夏菌源发源地，初始菌量，并结合气象数据的分析研究菌源传播大致的规律。另一途径是在甘肃不同海拔越夏区定点取样，应用分子标记，获取菌源群体遗传结构方面的信息。然后应用间接和直接两种分析方法对数据进行深入分析。 间接方法获得基因流方面的信息，直接方法获得传播路径和传播速率方面的信息。将以上两个研究途经获得的信息结合深入分析，可望获得小麦条锈菌在甘肃越夏不同地区越夏菌源的起源地点、周年动态，传播走向和可能的传播速率等方面的信息。有助于进一步了解菌源在甘肃越夏区的传播规律，缩小越夏菌源初始起源的搜寻范围，确定传播的上游地区和关键因素，为我国条锈病越夏区菌源地集中治理提供科学依据。

本研究自2014年起，在4年的时间里，通过完善和运用定量测定空气中的孢子浓度和分子群体遗传学手段测定传播路线和速率两种研究途径，以甘肃不同海拔越夏区为基地，集中开展了小麦条锈病菌源初始源和传播路径和速率的研究。定量分析了空气中孢子浓度监测越夏菌量动态，估计越夏菌源发源地，初始菌量，并结合气象数据的分析研究了菌源传播大致的规律。研究中，在甘肃不同海拔越夏区定点取样，应用分子标记，获取菌源群体遗传结构方面的信息，然后应用间接和直接两种分析方法对数据进行深入分析。 间接方法获得了基因流方面的信息，直接方法获得了传播路径和传播速率方面的信息。将以上两个研究途经获得的信息结合深入分析，获得了小麦条锈菌在甘肃越夏不同地区越夏菌源的起源地点、周年动态，传播走向和可能的传播速率等方面的信息。研究对进一步了解菌源在甘肃越夏区的传播规律，缩小越夏菌源初始起源的搜寻范围，确定传播的上游地区和关键因素，为我国条锈病越夏区菌源地集中治理提供了科学依据。