McDonald Tami, Brown Daren, Keller Nancy P, Hammond Thomas M
Department of Plant Pathology, University of Wisconsin, Madison, USA.
Mol Plant Microbe Interact. 2005 Jun;18(6):539-45. doi: 10.1094/MPMI-18-0539.
Mycotoxins are natural fungal products that are defined by their harmful effects on humans and animals. Aflatoxin contamination of maize by Aspergillus species and trichothecene contamination of small grains by Fusarium species are two of the most severe mycotoxin problems in the United States. We are investigating RNA silencing in an effort to identify novel ways to control mycotoxin contamination of crops. Transformation of two Aspergilli (A. flavus and A. parasiticus) and a Fusarium (F. graminearum) with inverted repeat transgenes (IRT) containing sequences of mycotoxin-specific regulatory genes suppressed mycotoxin production in all three plant-pathogenic fungi. This atoxigenic phenotype was stable during infection on corn and wheat, and importantly, F. graminearum IRT strains were less virulent on wheat than were wild type. The IRT did not alter physiological characteristics of the fungi, such as spore production and growth rate on solid media. These results indicate that RNA silencing exists in Aspergillus and Fusarium plant pathogens and suggest that RNA silencing technology may be a useful tool for eliminating mycotoxin contamination of agricultural products.
霉菌毒素是天然的真菌产物，其定义基于它们对人类和动物的有害影响。曲霉菌种对玉米的黄曲霉毒素污染以及镰刀菌属对小粒谷物的单端孢霉烯族毒素污染是美国最严重的两种霉菌毒素问题。我们正在研究RNA沉默，以努力确定控制农作物霉菌毒素污染的新方法。用含有霉菌毒素特异性调控基因序列的反向重复转基因（IRT）转化两种曲霉菌（黄曲霉和寄生曲霉）和一种镰刀菌（禾谷镰刀菌），抑制了所有这三种植物病原真菌中的霉菌毒素产生。这种无毒素产生的表型在玉米和小麦感染期间是稳定的，重要的是，禾谷镰刀菌IRT菌株在小麦上的毒性比野生型菌株低。IRT没有改变真菌的生理特性，如孢子产生和在固体培养基上的生长速率。这些结果表明RNA沉默存在于曲霉属和镰刀菌属植物病原体中，并表明RNA沉默技术可能是消除农产品霉菌毒素污染的有用工具。
