Determining Morphological and Physiological Plasticity in Local Populations of Glechoma hederacea. Comparison of “Virescent-Like” Mutant with Occurring Range of Morphologies and Physiologies.

Glechoma hederacea, is an invasive herbaceous plant used as a model system for ecophysiological research. A somatic mutant termed “virescent-like” expressing distinct phenotypes relative to the wild type -- reduced volatiles, reduced starch accumulation, pest resistance, increased size and number of trichomes, and increased leaf lobing -- was identified in a local population. Our objectives were to more thoroughly characterize the mutant, and to establish the amount of morphological and physiological variability occurring in local populations so we could more accurately attribute the impacts of the “virescent-like” mutation. In field plots, the mutant was only able to survive in deep shade, while representative wildtypes proliferated in shade, partial shade, and full sun. Mutant plants retrieved from the field site after exposure to cold and declining temperatures of autumn flowered prolifically, while wildtypes flowered minimally or not at all. No seed production was observed on the mutant, however. Data collected from plants grown in deep shade field plots showed that leaves of the mutant had a markedly increased number of lobes compared to three different wildtypes, a decreased dry mass to fresh mass ratio, and protein content comparable to wildtypes. Comparison of mutant and wildtype chloroplast genomes (“plastomes”) revealed 24 substituted sites; consequently ISSR analysis was employed to confirm that these plants were in fact members of the same species. Comparison of mutant and wildtype core metabolic enzyme activities also showed altered levels for some enzymes, such as malate dehydrogenase