Assessing fruit diversity within subtribe Physalidinae (Solanaceae)

Abstract Typical Physalidinae fruits are fleshy, and although uncommon, dry fruits are present in a few species. The development of fleshy fruits has been widely studied due to their economic importance, while less is known about the development of dry fruits. Our study compared the anatomical development of the fleshy fruits of Physalis angulata , P. gracilis and Tzeltalia amphitricha , the dry indehiscent fruits of Chamaesaracha crenata , P. nicandroides , and P. pruinosa , and the dry dehiscent fruits of Cataracta microphysa and Quincula lobata . Three fruits from three different individuals of each species were collected at a young, intermediate, and mature stage for a total of 27 fruits per species. Fruits were fixed in FAA and methanol. Anatomic characterization using standard procedures with paraffin microtome sections and staining was performed. Samples were observed with light and electron microscopes. Measures of the exocarp, mesocarp, and endocarp were taken at the three different stages. The ancestral character state for the type of fruits in Physalidinae was estimated based on a phylogeny using three nDNA and one cpDNA region, performed with Bayesian inference. Results show that the mesocarp and endocarp change through development. The size of fleshy fruits depends on cellular expansion and proliferation of the mesocarp and endocarp. Dry indehiscent fruits have three fruit layers, but as the fruits mature, the mesocarp and endocarp develop lacunae, and the fruit becomes thin. Young dry dehiscent fruits initially have three fruit layers, but as the fruit develops, lacunae form, leading to mesocarp and endocarp degradation and in some cases, endocarp lignification. The common ancestor most probably had fleshy fruits, and dry fruits evolved at least six times independently within the subtribe. Dry fruits are not exclusive to arid environments. We confirm that subtribe Physalidinae has three different fruit types: the well‐known fleshy berry, a dry indehiscent fruit (carcerulus), and a dry dehiscent fruit.