Genetic diversity of Saccharum complex using ISSR markers.

Sugarcane (Saccharum sp, Poaceae) is native to Southeast Asia, and due to growing demand as raw material, its cultivation recently expanded to new frontiers. The genetic diversity analysis is essential for targeting strategies in the formation and maintenance of a germplasm. This study aimed to assess the genetic diversity of 26 accessions of sugarcane from the Active Germplasm Bank of Embrapa Coastal Tablelands, using inter-simple sequence repeat (ISSR) molecular markers. Sixteen primers were used, resulting in 87 fragments with 91.13% of polymorphism. The similarity of the individuals ranged between 0.22 and 0.87. Individuals RB867515 and RB92579 were closer genetically, and the most distant ones were PI240785 and NSL 291970. Four distinct clusters were formed, using UPGMA. This information can be used to prioritize the selection of accessions for the conduction of hybridization in breeding and germplasm exchange actions.

Analysis of genetic diversity of Hyptis pectinata (L.) Poit. plants using ISSR markers.

Hyptis pectinata, popularly known as 'sambacaitá' or 'canudinho', is a medicinal and aromatic species widely used in the Brazilian Northeast. In Sergipe, the excessive extraction of natural resources may reduce the genetic variability of native plants. Thus, molecular markers have frequently been applied to the characterization of genetic diversity as the basis for germplasm conservation and breeding programs. The objective of the present study was to evaluate the genetic diversity of H. pectinata plants collected in different municipalities of the State of Sergipe using ISSR molecular markers. Thirty-four primers were tested, nine of which were selected for providing reproducible and analyzable amplification products, resulting in 67 polymorphic bands. The expected heterozygosity ranged from 0.32 to 0.45, with a mean of 0.39. Polymorphism information content was of 0.49, which classifies the markers as moderately informative. A dendrogram was constructed using unweighted pair group method with arithmetic mean, forming three clusters: Cluster I (79 plants); Cluster II (4 plants); and Cluster III (2 plants). Jaccard's similarity coefficients ranged from 0.06 to 0.98. The plants SAM-117 and SAM-119 presented greater similarity. Conversely, SAM-107 and SAM-171 were the most genetically distant. In general, H. pectinata plants collected in the State of Sergipe presented low to moderate genetic diversity.

Genetic diversity of native populations of Croton tetradenius Baill. using ISSR markers.

Brazil has about 300 Croton species in different types of vegetation. Croton tetradenius Baill., which is endemic to the Northeast region and predominant in the Caatinga vegetation, stands out among the several species of this genus. Considering the importance of knowing the genetic variability of a species, the objective of this study was to analyze the genetic diversity of the genotypes of natural populations of C. tetradenius in the State of Sergipe, using ISSR molecular markers. Forty individuals were sampled in four natural populations of the State of Sergipe, Brazil. Thirteen primers were used for DNA amplification using ISSR-PCR, totaling 77 amplified fragments, of which 94.8% were polymorphic. Results of the cluster analysis obtained by the Jaccard's similarity index, using the UPGMA method, resulted in the formation of six distinct clusters. Analysis of molecular variance (AMOVA), used to estimate the genetic variability among populations, revealed significant genetic variance (P < 0.01) between and within the studied populations, and most of the genetic diversity was found (87%) within populations. According to the Jaccard's similarity index, none of the studied plants was genetically identical. CTE210 and CTE305 presented high similarity index (0.76), while CTE105 presented low similarity index (<0.16) with all related individuals. ISSR markers were efficient and allowed the formation of a molecular profile, and had sufficient polymorphism to estimate the genetic variability between the accessions of the studied populations.

Diversity and genetic stability in banana genotypes in a breeding program using inter simple sequence repeats (ISSR) markers.

Banana (Musa spp) is a fruit species frequently cultivated and consumed worldwide. Molecular markers are important for estimating genetic diversity in germplasm and between genotypes in breeding programs. The objective of this study was to analyze the genetic diversity of 21 banana genotypes (FHIA 23, PA42-44, Maçã, Pacovan Ken, Bucaneiro, YB42-47, Grand Naine, Tropical, FHIA 18, PA94-01, YB42-17, Enxerto, Japira, Pacovã, Prata-Anã, Maravilha, PV79-34, Caipira, Princesa, Garantida, and Thap Maeo), by using inter-simple sequence repeat (ISSR) markers. Material was generated from the banana breeding program of Embrapa Cassava & Fruits and evaluated at Embrapa Coastal Tablelands. The 12 primers used in this study generated 97.5% polymorphism. Four clusters were identified among the different genotypes studied, and the sum of the first two principal components was 48.91%. From the Unweighted Pair Group Method using Arithmetic averages (UPGMA) dendrogram, it was possible to identify two main clusters and subclusters. Two genotypes (Garantida and Thap Maeo) remained isolated from the others, both in the UPGMA clustering and in the principal cordinate analysis (PCoA). Using ISSR markers, we could analyze the genetic diversity of the studied material and state that these markers were efficient at detecting sufficient polymorphism to estimate the genetic variability in banana genotypes.

Analysis of genetic diversity of a native population of Myrcia lundiana Kiaersk. plants using ISSR markers.

Myrcia lundiana Kiaersk. is a tree of the family Myrtaceae found in tropical and subtropical areas of the southern hemisphere that produces essential oil. The aim of this study was to characterize the genetic diversity of M. lundiana plants from a native population of Parque Nacional de Itabaiana, using inter-simple sequence repeat molecular markers. Thirty-five primers were tested, 20 of which were polymorphic, resulting in 135 polymorphic and informative bands. Results of the cluster analysis, obtained using the unweighted pair group method with arithmetic mean, grouped plants into three clusters: Cluster I - MLU001, MLU002, MLU003, MLU004, MLU005, MLU006, MLU018, MLU019, MLU020, MLU021, MLU022; MLU008, MLU011, MLU012, MLU014, MLU015, MLU017, MLU026, and MLU028; Cluster II - MLU007, MLU009, MLU010, MLU013, and MLU016; and Cluster III - MLU023, MLU024, MLU025, and MLU027. Jaccard similarity coefficients for pair-wise comparisons of plants ranged between 0.15 and 0.87. MLU014 and MLU015 presented low genetic diversity, with a similarity index of 0.87. Conversely, MLU007 and MLU019 presented high diversity, with a similarity index of 0.15. According to the structure analysis, three distinct clusters were formed. Genetic diversity of M. lundiana plants was intermediate, and expansion of its genetic diversity is necessary. MLU026 and MLU028 are the most suitable for selection in breeding programs, since they clearly represent all of the diversity present in these plants. Moreover, these results provide important information on the existing genetic variability, highlighting the importance of Parque Nacional de Itabaiana for the conservation of this species.

Estimation of genetic diversity in a natural population of cambui tree (Myrciaria tenella O. Berg) using ISSR markers.

Cambui (Myrciaria tenella O. Berg) is a native species from Brazil, which belongs to the family Myrtaceae. Molecular characterization is one of the most used tools for the study of the biotechnological potential of species because the diversity level between individuals can be inferred. Analysis of genetic diversity is fundamental to the direction of the strategies necessary to form and maintain a germplasm. This study aimed to evaluate the genetic diversity in a natural population of cambui using inter-simple sequence repeat (ISSR) molecular markers. The natural population, which provided the plant material, is found at the Private Reserve of Natural Heritage of Caju, which belongs to the experimental field of Embrapa Tabuleiros Costeiros, in the municipality of Itaporanga d'Ajuda, SE, Brazil. Young leaves of each individual were collected for DNA extraction and analysis of PCR-ISSR. Thirty primers were tested and the top 10 were selected. The use of these primers resulted in 71 fragments with 98.3% polymorphism. Similarity of individuals ranged between 0.30 and 0.92. The most similar individuals were C13 and C17 and the most distant were C1 and C41. Through UPGMA, six distinct groups were identified. This information may be used for conservation of these genetic resources, germplasm exchange, creation of germplasm bank and in future studies with this species.

Genetic diversity in natural populations of mangaba in Sergipe, the largest producer State in Brazil.

Mangaba (Hancornia speciosa Gomes) is found in areas of coastal tablelands in the Brazilian Northeast and Cerrado regions. This species has been subjected to habitat fragmentation that is mainly due to human activity, and requires conservation strategies. The aim of this study was to analyze the structure and inter- and intrapopulation genetic diversity of natural populations of H. speciosa Gomes using inter-simple sequence repeat (ISSR) molecular markers. A total of 155 individuals were sampled in 10 natural populations (ITA, PAC, IND, EST, BC, PIR, JAP, BG, NEO, and SANT) in the State of Sergipe, Brazil. Fifteen primers were used to generate 162 fragments with 100% polymorphism. Genetic analysis showed that the variability between populations (77%) was higher than within populations (23%). It was possible to identify five different groups by the unweighted pair group method with arithmetic mean and principal coordinate analysis, and only one individual (E10) remained isolated. Using ISSR markers it was possible to obtain a molecular profile of the populations evaluated, showing that these markers were effective and exhibited sufficient polymorphism to estimate the genetic variability of natural populations of H. speciosa Gomes.

Genetic diversity analysis of Varronia curassavica Jacq. accessions using ISSR markers.

Varronia curassavica Jacq. is a medicinal and aromatic plant from Brazil with significant economic importance. Studies on genetic diversity in active germplasm banks (AGB) are essential for conservation and breeding programs. The aim of this study was to analyze the genetic diversity of V. curassavica accessions of the AGB of Medicinal and Aromatic Plants of the Federal University of Sergipe (UFS), using inter-simple sequence repeat molecular markers. Twenty-four primers were tested, and 14 were polymorphic and informative, resulting in 149 bands with 97.98% polymorphism. The UPGMA dendrogram divided the accessions into Clusters I and II. Jaccard similarity coefficients for pair-wise comparisons of accessions ranged between 0.24 and 0.78. The pairs of accessions VCUR-001/VCUR-503, VCUR-001/VCUR-504, and VCUR-104/VCUR-501 showed relatively low similarity (0.24), and the pair of accessions VCUR-402/VCUR- 403 showed medium similarity (0.78). Twenty-eight accessions were divided into three distinct clusters, according to the STRUCTURE analysis. The genetic diversity of V. curassavica in the AGB of UFS is low to medium, and it requires expansion. Accession VCUR-802 is the most suitable for selection in breeding program of this species, since it clearly represents all of the diversity present in the AGB.

Diversity and genetic structure of mangaba remnants in states of northeastern Brazil.

In this study, we analyzed the genetic diversity and structure of remnants of mangaba populations in states of northeastern Brazil by applying 9 microsatellite markers previously developed to establish conservation strategies for germplasm and species preservation. Six to 20 individuals per population were analyzed, with a total of 94 individuals and 6 populations from the states of Ceará, Pernambuco, and Sergipe, Brazil. The intra-population positive fixation index (f) in all populations indicated inbreeding resulting from the lack of random mating. The mean genetic diversity index values GST, FST, and RST estimated for divergence among the 6 populations were 0.14 (P < 0.05), revealing moderate genetic differentiation. The smallest FST value (P ≥ 0.05) was observed between the Jacarecoara and Tapera populations (0.005) and the highest between the Barra dos Coqueiros and Jacarecoara populations (0.287). The Jacarecoara population was the most divergent among the populations analyzed. According to analysis of molecular variance results, the largest variation percentage resulted from variability within populations (83.18%). Bayesian clustering analysis showed the formation of 2 sets (K = 2). Our results are important for developing strategies for in situ conservation of the species, seed collection, and ex situ conservation. For both methods, conservation of the greatest possible genetic variability of the species is essential.