Assessing Genetic Diversity in Mexican Husk Tomato Species

Mexico is the center of diversity of the husk tomato (Physalis L., Solanaceae), which includes a number of commercially important edible and ornamental species. Taxonomic identification is presently based on morphological characteristics, but the presence of high inter- and intraspecific morphological variation makes this task difficult. Six ISSR primers were used on eight Mexican species of Physalis to determine their utility for interspecific taxonomic discrimination and to assess their potential for inferring interspecific relationships. The six ISSR primers amplified 101 bands, with 100% polymorphism across samples. The number of bands per primer varied from 10 to 21. All primers produced different fingerprint profiles for each species, confirming the ISSR value in taxonomic discrimination. Discrimination values based on Simpson’s diversity index varied from 0.48 to 0.58. Genetic interspecific similarity values ranged from 0.20 to 0.57, and intraspecific similarity values were highest for Physalis angulata (0.71), followed by Physalis philadelphica (0.63) and Physalis lagascae (0.55). The UPGMA analysis grouped accessions of the same species together and clustered together Physalis species of similar morphological traits. Thus, ISSR markers are useful in estimating genetic relationships in Physalis.     

Richness,geographic distribution patterns,and areas of endemism of selected angiosperm groups in Mexico

Mexico is a megadiverse country. Presently, 22 126 species of angiosperms have been registered within its territory and 11 001 are considered to be endemic. However, their geographical distributions are far from homogeneous. In addition, Mexico is the center of diversification of several groups. Our analysis focused on such groups. The aims were to identify areas of species richness and endemism. A data matrix with 766 species and 25 579 geographical records was analyzed. It included Calochortus (Liliaceae); Bletia (Orchidaceae); Tigridieae (Iridaceae); Amaryllidaceae; Poliantheae, Echeandia (Asparagaceae); Crassulaceae; Hylocereus (Cactaceae); Solanum, Lycianthes and Physalinae (Solanaceae); Salvia section Membranaceae (Lamiaceae); and Cosmos and Dahlia (Asteraceae). Using Geographic Information Systems, we determined richness and distribution based on: (i) Mexican political divisions, (ii) biogeographical regions and provinces, (iii) a grid of 0.5 × 0.5° cells, and (iv) elevation. The areas of endemism were estimated using the endemicity analysis. The highest number of taxa and endemic plants were concentrated within the Transmexican Volcanic Belt in the Mexican Transition Zone. This mountain range has been recognized as a province on the basis of geologic, tectonic, geomorphologic, physiographic and biogeographic criteria. It is a 1000 km long volcanic arc that extends east to west through Central Mexico and is variably from 80 to 230 km wide, between 17°30′ to 20°25′N and 96°20′ to 105°20′W. Our results represent a local deviation from the global richness latitudinal gradient of angiosperm species.     

Geographic isolation and long-distance gene flow influence the genetic structure of the blue fan palm Brahea armata (Arecaceae)

Journal of Plant Research - The formation of the Baja California Peninsula (BCP) has impacted the microevolutionary dynamics of different species in ways that depend on biological traits such as...