Phytotoxins clear the way

Invading plant species, such as the Centaurea, establish monocultures in novel habitats by displacing the indigenous plant communities. It is thought that the absence of "natural enemies" and/or the release of phytotoxins from the invading plants by allelopathy promote this process. Previous work has shown that the European spotted knapweed (Centaurea maculosa) releases racemic catechin; the phytotoxin (-)-catechin, and the antimicrobial (+)-catechin. Invasive (-)-catechin levels in North American soil were found to be more than double those found in the natural habitats of C. maculosa. In the September 5 Science, Harsh Bias and colleagues at Colorado State University show that (-)-catechin inhibits growth of a number of nature North American plants by altering gene expression, resulting in extensive root death (Science, 301:1377-1380, September 5, 2003).

Bias et al. used an integrated approach to establish the characteristics of (-)-catechin-mediated inhibition of plant growth. They observed that when field soil was supplemented ...