Diversity and genetic structure of the husk tomato (Physalis philadelphica Lam.) in Western Mexico

Physalis is an American plant genus that includes species of economic importance for their edible fruit. Consumption of this fruit is a historic tradition in Mexico. Physalis philadelphica is one of the most abundant species, which can grow under wild, weedy or cultivated conditions. It presents high morphological variability in terms of vegetative and reproductive traits; however, no study has been made of its genetic diversity or the impact of human activity on its diversity and differentiation patterns. We determined genetic parameters in nine populations representing a management gradient, including three wild, three weedy and three cultivated populations, using 88 inter-simple sequence repeat markers. The diversity of the total gene pool was high (Ht\ua0=\ua00.292, HTB\ua0=\ua00.319) and did not decrease with the intensity degree of management. Reproductive system, life form and the wide distribution determined the genetic variation of the taxon. AMOVA revealed high variation within the total gene pool (44.3\ua0%) and among populations (46.7\ua0%). This was influenced by pollinator behavior, dispersal form, geographic discontinuity of the studied populations and human selection. Variation among population management categories was lower (9\ua0%), indicating that this variable has little effect, most likely due to the broad gene pool of the taxon. However, analysis of genetic distance and Bayesian assignment distinguished two groups: cultivated and wild, with weedy populations interspersed between. This result suggests that selection for agricultural and morphological attributes of P. philadelphica contributes to this differentiation. Future studies could address the evolutionary dynamics of the wild–weedy–domesticated complex. © 2014, Springer Science+Business Media Dordrecht