Morphological variation related with environmental factors in endemic and threatened <Emphasis Type="Italic">Jatropha</Emphasis> species of Tehuacan-Cuicatlan,Mexico

Jatropha spp. from Mexico includes high species richness and endemism; five species inhabit in the Tehuacan-Cuicatlan Biosphere Reserve (TCBR), and they are important resources as food, medicine and biofuel. The assessment of morphological and agronomic characteristics is essential to identify, use and maintain plant genetic resources. Given the lack of information on the morphological variability of Jatropha species in relation to environment, the objective was to analyze the influence of physiographic, climatic, and anthropogenic factors in the morphological variability of the species: Jatropha neopauciflora and J. rzedowskii, both not-endangered; J. oaxacana, special protection; J. ciliata and J. rufescens, both endangered in the Reserve. Twelve quantitative morphological variables were measured in 24 populations of these species; 14 environmental variables were registered, and the disturbance index in the sites was estimated. The information was analyzed with Principal Components Analysis (PCA), Cluster Analysis and Canonical Correspondence Analysis (CCA). PCA detected interspecific variation: J. ciliata and J. rufescens have longer and broader leaves and longer flowers, while the other three species have smaller leaves and flowers. J. oaxacana population has intermediate size of leaves, fruits and seeds, compared with those of J. neopauciflora and J. rzedowskii. CCA detected intra-specific variation among the populations of J. neopauciflora and J. rzedowskii, which were separated in two groups due to fruit and seed size. Axis 1 of CCA correlated positively with altitude and annual temperature range, and negatively with mean annual temperature; at the intra-specific level, both species are adapted to variations of temperature and altitude.     

Distribution and eco-geographic characterization of Carica papaya L. native to Mexico

Genetic Resources and Crop Evolution - Carica papaya L. is an important plant genetic resource that has a low level of genetic erosion. Knowing the distribution and eco-geography of native C....     

The origin of <Emphasis Type="Italic">Datura metel</Emphasis> (Solanaceae): genetic and phylogenetic evidence

Using the analysis of nine isozyme systems and cladistic analysis of 32 morphological characters of the Mexican species of the section Dutra of the genus Datura, evidence was sought on the origin of the cultivated D. metel L. The genetic similarity and the phylogenetic relationship suggest that D. metel is related more closely to D. inoxia Mill. than to the other taxa of the section Dutra based upon the small genetic distance between them. The cladistic analysis revealed two main clades: the long-lived, tuberous rooted perennials (D. inoxia, D. lanosa A.S. Barclay ex Bye, D. metel, and D. wrightii Regel) and the tap-rooted annuals (D. discolor Bernh., D. kymatocarpa A.S. Barclay, D. leichhardtii F.V. Muell. ex Benth. ssp. pruinosa (Greenm.) Barclay ex Hammer (syn.: D. pruinosa Greenm.), D. reburra A.S. Barclay). Datura inoxia is the sister taxon of D. metel next to which is D. wrightii while D. lanosa is the basal taxon of this group. The combination of genetic and cladistic data indicates that D. inoxia is most likely the progenitor of D. metel.