Patterns of Clonal Variation in Skeleton Weed (Chondrilla juncea), an Apomictic Species

Abstract

Isozymes were used to discriminate clones of the apomictic plant, Chondrilla juncea L. (Asteraceae), a Eurasian species that has become a major weed of cereal cultivations in Australia. The sample that was screened consisted of the progeny of single plants from each of 123 sites in central Turkey. When used in combination, six polymorphic enzyme systems separated 91 distinct clones. Seventy-four percent of samples detected unique clones, none of these being widespread. Chromosome counts established that these clones are triploid. This pattern contrasted with that found in a survey of 23 populations in southeastern Australia. Apart from the narrow-leaf rust susceptible clone, the survey found two additional multilocus genotypes only, both of which are immune to the introduced strain of the rust.