Fusarium wilt of banana and Wallace's line: Was the disease originally restricted to his Indo-Malayan region?

Abstract

The edible bananas originated in Asia. Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. cubense, is a lethal disease of this important food crop. Also known as Panama disease, it impacts on a wide range of cultivars and, like its host, is now found throughout the tropical regions of the world. Although most authorities believe that the pathogen co-evolved with banana, a non-Asian origin is also possible. Before global collections of F. oxysporum f sp. cubense became available, there was scant evidence to support either of these hypotheses. New information on genetic diversity in the fungus, and its ancestry, confirms that it most likely originated in south and southeast Asia. The available data indicate that the eastern limit of its native range was probably defined by the 1910 version of Wallace’s line; its distribution coincided with his Indo-Malayan region. We believe that this is the first time that Wallace’s line has been shown to delimit the distribution of a microorganism, F. oxysporum f sp. cubense.