ABSTRACT. Jatropha curcas L. is a highly promising oilseed for sustainable production of biofuels and bio-kerosene due to its high oil content and excellent quality. However, it is a perennial and incipiently domesticated species with none stable cultivar created until now despite genetic breeding programs in progress in several countries. Knowledge of the genetic structure and diversity of the species is a necessary step for breeding programs. The molecular marker can be used as a tool for speed up the process. This study was carried out to assess genetic diversity of a germplasm bank represented by J. curcas accessions from different provenance beside interspecific hybrid and backcrosses generated by IAC breeding programs using inter-simple sequence repeat markers. The molecular study revealed 271 bands of which 98.9% were polymorphic with an average of 22.7 polymorphic bands per primer. Genetic diversity of the germplasm evaluated was slightly higher than other germplasm around the world and ranged from 0.55 to 0.86 with an average of 0.59 (Jaccard index). Cluster analysis (UPGMA) revealed no clear grouping as to the geographical origin of accessions, consistent with genetic structure analysis using the Structure software. For diversity analysis between groups, accessions were divided into eight groups by origin. Nei's genetic distance between groups was 0.14. The results showed the importance of Mexican accessions, congeneric wild species, and interspecific hybrids for conservation and development of new genotypes in breeding programs.
The Arecaceae family has a worldwide distribution, specially in the tropical and subtropical regions. We sequenced the chloroplast genome of Acrocomia intumescens and A. totai, widely used in the food and energy industry, Bactris gasipaes, important for palm heart, Copernicia alba and C. prunifera, worldwide known for wax utilization, and Syagrus romanzoffiana, of great ornamental potential. Copernicia spp. showed the largest chloroplast genomes (C. prunifera: 157,323 bp and C. alba: 157,192 bp), while B. gasipaes presented the smallest (155,078 bp). Copernicia spp. had two more gene copies (trnL-GAG) than the others, and S. romanzoffianaunderwent pseudogenization in one copy of rps19. Structurally, great synteny was detected among palms. Conservation was also observed in the distribution of single sequence repeats (SSR). Copernicia spp. presented less dispersed repeats, without occurrence in the small single copy (SSC). All RNA editing sites were C (cytidine) to U (uridine) conversions. Overall, closer phylogenetically species shared more sites. Almost all nodes of the phylogenetic analysis showed posterior probability (PP) of 1.0, reaffirming the close relationship between Acrocomia species. These results elucidate the conservation among palm chloroplast genomes but point to subtle structural changes, providing support for the evolutionary dynamics of the Arecaceae family.
Thinning intensities to increase the size and weight of mangosteen fruits (Garcinia mangostana L.
Anagroforestry system was established in steeplands of the municipality of Tezonapa Veracruz, Mexico, with objective of evaluating its efficiency in soil conservation. The component species of the system were mahogany (Swietenia macrophylla), cedar tree (Cedrelaodorata), teak (Tectonagrandis), orange (Citrus sinensis), lemon (Citrus latifolia), cinnamon (Cynnamomunzeylanicum), corn (Zea mays), and biological barriers to the contour (BBC) of vetiver grass (Vetiveria zizanioides). In agroforestry system, the annual soil erosion rate was reduced by 66% compared to the traditional system used for maize production.
The objective of the work was to validate the technical and economic efficiency of thinning to increase the size and weight of mangosteen fruits. The validation was carried out in 2021, in two commercial plantations of mangosteen 10 and 13 years old located in the municipalities of Tapachula, and Tuxtla Chico, Chiapas, Mexico, respectively. The factors in study are thinning with two levels: thinned 30% and unthinned (control) and three initial fruiting ranges (RFI): 80-120 fruits; 121 to 160 fruits and> 160 fruits. By combining the study factors, 6 treatments were formed: RFI 80-120-thinned; RFI 121-160-thinned; RFI >160-thinned; RFI 80-120-unthinned RFI 121-160-unthinned and RFI >160-unthinned. A completely random design with four repetitions was used. The experimental unit consisted of a tree, with a total of 24 trees in 0.14 ha in each plantation under study. The study variables were yield/tree; fruit weight and fruits/tree. The economic comparison between treatments was made and the return to capital (cost-benefit ratio) of them was calculated. In both plantations evaluated, a significant statistical difference was found in fruits/tree, fruit weight, yield/tree and yield/ha. The highest average weight of the fruits (> 76 g in accordance with the requirements of international markets.) and percentage of them, is obtained in trees thinned. The highest cost-benefit ratio (4.5 in Tuxtla Chico plantation and 2.3 in Tapachula plantation), was obtained in RFI >160 thinned treatment.
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