No abstract

-The objective of this work was to evaluate the occurrence of polyembryony in the mango cultivars Manila and Ataulfo, and to determine whether seedlings cultured in vitro are zygotic or nucelar. Percentage of polyembryony was calculated and the number of embryos in 100 seeds of each cultivar was recorded. 'Manila' exhibited 97% polyembryony with 3.4 embryos per seed, while 'Ataulfo' had 95% polyembryony with 3.2 embryos per seed. Later, 20 seeds of each cultivar were established in vitro, and it was analyzed those in which all embryos germinated (12 seeds from 'Manila' and 7 from 'Ataulfo'). DNA was extracted from seedling leaf tissue, and its origin was identified with 14 RAPD primers. The polymorphic markers recognized the seedlings of sexual origin in seven of nine 'Manila' polyembryonic seeds, and in four of seven 'Ataulfo' ones. Also, in polyembryonic seeds not all zygotic seedlings were produced by small embryos located at the micropyle.Index terms: Mangifera indica, embryo culture, funiculus, molecular markers, polymorphism. Identificação de plântulas zigóticas e nucelares em cultivares de manga poliembriônicasResumo -O objetivo deste trabalho foi avaliar a ocorrência de poliembrionia nas mangas 'Manila' e 'Ataulfo' e determinar se as plântulas cultivadas in vitro são zigóticas ou nucelares. A percentagem de poliembrionia foi calculada e o número de embriões em 100 sementes de cada cultivar foi determinado. 'Manila' apresentou 97% de poliembrionia com 3,4 embriões por semente, enquanto 'Ataulfo' teve 95% de poliembrionia com 3,2 embriões por semente. Posteriormente, 20 sementes de cada cultivar foram cultivadas in vitro, tendose analisado aquelas em que todos os embriões germinaram (12 sementes de 'Manila' e sete de 'Ataulfo'). O DNA foi extraído a partir de tecidos foliares das plântulas, e sua origem foi identificada com 14 iniciadores RAPD. Os marcadores polimórficos reconheceram o embrião de origem sexual em sete das nove sementes poliembriônicas de 'Manila' e em quatro das sete sementes de 'Ataulfo'. Além disso, nem todas as plântulas zigóticas foram produzidas por embriões pequenos localizados no micrófilo das sementes poliembriônicas.Termos para indexação: Mangifera indica, cultura de embriões, funículo, marcadores moleculares, polimorfismo.

Non-timber forest products (NTFPs) are essential for community development, but their enormous demand has posed a serious threat to trees growing in their natural habitat. Copal resin is one of these products, which has a great deal of religious and ceremonial significance in Mexico and around the world. Resin extraction from a tree depends on its morphological and physiological characteristics, as well as its physical and sanitary condition. In this study, a methodology was proposed for determining the yield and health status of Copal trees, and a random forest (RF) model was developed to explain their resin production based on their morphological and condition characteristics. The experiment was conducted in the Agua Escondida watershed in Puebla, Mexico. With the training data, the average accuracy of the model was 99%, with a Kappa index of 98%, which is considered an excellent level of agreement beyond chance, and with the validation data, the average accuracy was 71% and 47%, which is considered a good level of agreement beyond chance. Tree condition was the most important factor affecting resin production in Copal trees, followed by stem diameter (33 and 38 cm), height (2 and 2.5 m), and diameter of secondary branches (from 8 to 15, 22 and 32 cm).

The Tula watershed in Mexico, located in a semiarid and sub-humid climate zone, is experiencing intensive population growth, the expansion of mining concessions for construction materials, and agricultural and urban development, resulting in the degradation of soils and vegetation and a greater demand on natural resources. The aims of this study were to evaluate the survival rates and identify potential habitats within the Tula watershed for planting three non-native forage species (Atriplex canescens, Cynodon dactylon, and Leucaena collinsii) using the Kaplan-Meier estimator and the MaxEnt model with the purpose of rehabilitating degraded soils via agroforestry systems. There were 19 edaphoclimatic variables used and the occurrences of three species, obtained from the GBIF, MEXU, and SNIB databases. The models generated with MaxEnt were very accurate (area under the curve [AUC] ≥ 0.7). The species Atriplex canescens and Cynodon dactylon showed areas of potential planting sites (>0.4) and high survival rates (80% and 92%, respectively). The species Leucaena collinsii presented areas with lower potential planting (<0.4) but registered the greater survival rate (100%). The results provide a solid basis to evaluate the survival rates of forage species within potential planting sites in the Tula watershed using agroforestry systems to rehabilitate degraded soils.

Composition and floristic diversity of ecosystems subject to overexploitation, such as tropical deciduous forests where copal resin (Bursera bipinnata, Bursera copallifera) is extracted, are of great importance for understanding the ecological functioning of these ecosystems. This study analyzed the species composition and diversity in a natural population subject to copal extraction in San Juan Raboso Izúcar de Matamoros, Puebla, Mexico. A total of 54 sampling units were established, and the number of individuals and crown diameter for each tree species were recorded. For shrubs, succulents, acaulescent rosetophytes and climbers, the number of individuals and the area of cover were quantified. Based on the parameters of abundance, frequency, and relative dominance, the importance value index (IVI) was calculated. Diversity was evaluated using the Shannon index $$(H {^{\prime}})$$ ( H ′ ) . In total, 29 species were identified, distributed across 11 botanical families and 21 genera. The Fabaceae family was the richest, followed by the Burseraceae family, which includes the species that extract copal, but Opuntia streptacantha was the species with the most ecological weight. In this study, the Shannon index $$({H}^{^{\prime}})$$ ( H ′ ) averaged 1.45, which indicates that the community was mildly diverse.