我国黄曲霉遗传多样性、产毒特征及其地理分布的研究

A. flavus is not only a group of widely distributed saprobic,but also pathogenic and aflatoxin-producing fungi.The diversity of its isolates are distingushable based on morphological, physiological and some genetic characters. There exist different cryptic species and populations. The ambiguities in discriminating certain groups still remain unsolved,and the toxin-producing characters of certain goups are not well characterized...The toxic groups are usually distributed in tropical and arid areas with high temperature. But due to global unseasonal climate change,temperate areas are under the treats of these fungi. Most areas of China are located in the temperate, warm and subtropical zones. Predictablly,these areas will be facing the threats of these toxic groups.It is an urgent and important task to recognize different cryptic species and populations of A. flavus along with their toxin-producing characters and geographic distribution in China...Based on the isolates selected from different areas and environments of the three temperature zones along with the typical and type cultures, using the integrity of morphological, physiological and molecular methods,this study will focus on three issues: 1. To clarify different cryptic species and populations of A. flavus.2. To understand different cryptic species and populations and their toxin-producing characters.3. To investigate the geographic and environmental distribution of different cryptic species and populations in China.This study will provide scientific evidence for the gurarantee of food security, as well as prevention and control of these fungi in China.

黄曲霉是黄曲霉毒素的主要产生菌，也是动、植物条件致病菌且广泛分布于自然界。其菌株间在形态学、生理学和某些遗传学性状上差异很大，存在着多个隐存种和不同种群。黄曲霉某些类群的划分并不明确，有些类群的产毒特征也存在歧义。黄曲霉高产毒类群通常分布于热带和高温干旱地区。由于气候异常变化，温带地区正在受到高产毒类群的侵袭。因此系统调查我国黄曲霉遗传多样性、建立准确的黄曲霉各隐存种和种群与其产毒特征和地理分布的关系具有重要意义。本研究将分析我国三个温度带24省区不同环境中分离的黄曲霉菌株结合国际典型菌株和模式菌株，采用形态学、分子系统学、生理学和ISSR等分析方法从以下3个方面进行探讨：1.明确黄曲霉各隐存种和种群的划分。2.阐明我国黄曲霉各隐存种和种群种类及其产毒特征。3.揭示黄曲霉各隐存种和种群在我国不同地区和环境的分布。该结果将为我国黄曲霉的防控和粮食安全的评估提供科学依据。

黄曲霉是黄曲霉毒素(aflatoxin)的主要产生菌，也是动、植物条件致病菌。虽然黄曲霉广泛存在于自然界，但其主要分布于温带、亚热带、热带和高温干旱地区。全球的玉米、花生和大豆均不同程度地遭到黄曲霉和黄曲霉毒素的污染，我国更为严重。黄曲霉菌株间在形态学、遗传学和产毒特性上变异较大，致使黄曲霉的物种概念较为模糊而存在隐存种。本项目选取了我国4个温度带和1个气候区，即中温带、暖温带、亚热带、热带和青藏高原气候区的26省区不同环境中分离的黄曲霉88株并结合模式菌株和国际权威菌株15株共103株，采用多基因序列分型及产毒性状(AFB和CPA)进行研究，取得以下结果：1. 我国没有发现高产毒隐存种A. minisclerotigenes和A. parvisclerotigenu（该2种均产生黄曲霉毒素B, G和CPA）。2. 我国黄曲霉基本上可分为3个居群，米曲霉是其中一个居群。3. 黄曲霉各个居群与地理环境无关；毒素的产生具有菌株特异性，与居群无关；但米曲霉居群均不产黄曲霉毒素。