ABSTRACT. Mangabeira (Hancornia speciosa Gomes) is a fruit tree of the Apocynaceae family, which is native to Brazil and is a very important food resource for human populations in its areas of occurrence. Mangabeira fruit is collected as an extractive activity, and no domesticated varieties or breeding programs exist. Due to a reduction in the area of ecosystems where it occurs, mangabeira is threatened by genetic erosion in Brazil. The objective of this study was to characterize and evaluate the genetic diversity of 38 mangabeira individuals collected from natural populations in Pernambuco State using inter-simple sequence repeat (ISSR) molecular markers. The ISSR methodology generated a total of 93 loci; 10 were monomorphic and 83 were polymorphic. The average number of loci per (2015) primer was 15.5, ranging from 9 (#UBC 866) to 21 (#UBC 834). The results showed a high level of genetic diversity (0.30), and found that only around 30% of genetic variability is distributed among populations (G ST = 0.29, Ф ST = 0.30), with the remainder (Ф CT = 70%) found within each population, as expected for forest outcrossing species. Estimates for historic gene flow (1.18) indicate that there is some isolation of these populations, and some degree of genetic differentiation.
ABSTRACT. Studies of genetic diversity in plant species present in the remaining fragments of the Atlantic Forest are very important for understanding their resilience to such a degraded ecosystem. We analyzed the genetic diversity of 3 populations of the high-density understory species Metrodorea nigra St. Hill. (Rutaceae) located in forest remnants in the region of Ribeirão Preto, SP, Brazil (M13-Rib, BSQ-Rib, and FACCrav), by using simple sequence repeat (SSR) and inter-simple sequence repeat (ISSR) molecular markers for conservation purposes. A total of 133 polymorphic loci were observed in 136 inter-simple sequence repeat loci (average of 17 per primer). The Nei genetic diversity (H E ) was relatively high considering all populations (0.31). The BSQ-Rib population exhibited the highest value (0.27), followed by the M13-Rib (0.26) and FAC-Crav (0.24) populations. The simple sequence repeat markers analyzed showed a high number of alleles (K = 104), with an average of 14.85 alleles per locus. The average observed heterozygosity was 0.516 and the average expected heterozygosity was 0.771, ranging from 0.688 (FAC-Crav) to 0.765 (BSQ-Rib). The fixation indexes showed positive and significant differences from zero for all sample sets, indicating inbreeding, which may have resulted from the species' mating patterns and the barochoric seed dispersal system of M. nigra. Both markers indicated differentiation among populations, with higher values observed for inter-simple sequence repeat markers. No significant differences between juvenile and adult generations in any of the fragments were observed, indicating the resilience of M. nigra to the effects of fragmentation and reduced habitat.
ABSTRACT. The Neotropical Heliconia genus contains highly diversified plants and up to 220 species have been reported from the north of Mexico to the South of Brazil. Heliconia are cultivated as ornamental garden plants and as cut flowers. All species can be propagated by seeds or vegetatively, through rhizomes. Depending on the species, an individual plant can spread and form large clonal populations. H. bihai L., H. chartacea Lane ex Barreiros, and H. wagneriana Petersen are among the most cultivated Heliconia species. However, they still have undesirable characteristics that could be improved for the international market. This study aimed to characterize 15 half-sib families originating from commercial cultivations, by morphological and molecular markers. The genetic diversity (Ĥ E ), considering all individuals of the three species was 0.103. For H. bihai half-sib families, the value of Ĥ E was 0.242, showing high genetic diversity. The Ĥ E value for H. chartacea was 0.068, indicating low genetic diversity. All individuals of H. wagneriana showed the same band patterns, suggesting that the two parental plants were propagated vegetatively from the same plant and may have undergone some endogamic crossings. These results showed that molecular characterization can differentiate individuals closely related as half-siblings for H. bihai and H. chartacea, despite the low variation observed with morphological descriptors. The high genetic diversity observed in H. bihai half-sibling genotypes can provide valuable resources for breeding programs.
Malpighia emarginata is cultivated in almost all Brazil and is considered an important agricultural crop. The root-knot nematode Meloidogyne enterolobii has been described as a major threat to this crop, causing great production losses. Due to the scarcity of information about the severity of this parasite in M. emarginata plants in Brazil, this study investigated M. enterolobii resistance of ten M. emarginata genotypes from the active germplasm bank of Universidade Federal Rural de Pernambuco. The experiment was conducted adopting a completely randomized design in a factorial arrangement of 11 x 2 x 5, where M. emarginata cuttings were inoculated with 10,000 eggs in a greenhouse. After 150 days, plants were evaluated for the following parameters: gall index, egg mass index, number of eggs per root system, number of eggs per gram of root, and reproduction factor. The accessions showed different responses depending on host x pathogen interaction, from susceptibility to moderate tolerance. Accessions 027-CMF and 031-CMF were considered tolerant to the nematode and could be of great value in new breeding programs for resistance to M. enterolobii infection.
ABSTRACT. Plant parasitic nematodes infect a wide range of hosts representing the largest source of biotic stress experienced by plants. Meloidogyne genus comprises the most important parasitic nematodes, also known as root-knot nematodes. These parasitic organisms obtain nutrients to support their development through complex interactions with their hosts. The translationally-controlled tumor protein (TCTP) is widely expressed in eukaryotic organisms, and is related to a great diversity of biological processes such as calcium binding, cell proliferation and growth, pluripotency, regulation of apoptosis, microtubules stabilization, and histamine release. TCTP has been identified in the secretions of plant-parasitic nematodes, and may play a role in suppressing the plant immunity and programmed cell, hence promoting nematode parasitism. Our results revealed a high conservation of the evaluated protein sequences and little variation in their physicochemical characteristics, such as isoelectric points and hidropathicity. Phylogenetic analysis also revealed the presence of three main groups of TCTPs, corresponding to plant parasitic, animal parasitic and freeliving nematodes. Six plant parasitic TCTPs tertiary structure models were generated by homology modeling. The constructed models were highly similar and most of the structural variations occurred outside the characterized functional domains. To our knowledge, these are the first theoretical models of plant parasitic nematodes TCTPs and these results may provide a theoretical basis for future studies of host plant resistance to nematode infection.
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