Jorge Luiz Loyola Dantas

Correlações genéticas e análise de trilha para número de frutos comerciais por planta em mamoeiro

The objective of this work was to determine how the number of commercial fruit per plant (CFrP) is related to 16 morphological and agronomical traits in papaya (Carica papaya L.). The experiment was carried out in the 2008/2009-crop season, using an augmented randomized block design. Nineteen non-common (germplasm accessions) and three common genotypes (varieties and hybrids) were evaluated with ten repetitions. Correlations between CFrP and morpho-agronomic traits were outspread in direct and indirect effects. High variability was found for the evaluated traits. The estimates of genetic correlations were higher than phenotypic correlations for all characters. CFrP was positively and significantly correlated with number of fruits per axil (NFAx) and negatively with the internal diameter of the cavity of the fruit, pulp thickness, fruit weight, fruit length (FrL) and fruit diameter. However, path analysis showed that, among this traits, NFAx and FrL have more direct effect on CFrP. Furthermore, plant height, number of flowers per peduncle and leaf width are more easily measured and are expressed before fruit production, making them more suitable for indirect selection in breeding programs of this crop.

Polymorphism of Microsatellite Markers in Papaya (Carica papaya L.)

A set of 81 new microsatellite markers for Carica papaya L. previously identified by data mining using freely available sequence information from Genbank were tested for polymorphism using 30 germplasm accessions from the Papaya Germplasm Bank (PGM) at Embrapa Mandioca e Fruticultura Tropical (CNPMF) and 18 landraces. The data were used to estimate pairwise genetic distances between the genotypes. A neighbor-joining based dendrogram was used to define clusters and infer possible genetic structuring of the collection. Most microsatellites were polymorphic (73%), with an observed number of alleles per locus ranging from one to eleven. The levels of observed and expected heterozygosity for 51 polymorphic loci varied from 0.00 to 0.85 and from 0.08 to 0.82, averaging 0.19 and 0.59, respectively. Forty-four percent of microsatellites showed polymorphism information content (PIC) higher than 0.50. The compound microsatellites seem to be more informative than dinucleotide and trinucleotide repeats in average alleles per locus and PIC. Among dinucleotides, AG/TC or GA/CT repeat motifs exhibited more informativeness than TA/AT, GT/CA and TG/AC repeat motifs. The neighbor-joining analysis based on shared allele distance could differentiate all the papaya accessions and landraces as well as differences in their genetic structure. This set of markers will be useful for examining parentage, inbreeding and population structure in papaya.

Plant selection in F2 segregating populations of papaya from commercial hybrids.

The objective of this paper was to estimate the genetic parameters and additive genetic values in segregating populations of papaya using the mixed model methodology. Two F2 populations from Tainung and Calimosa hybrids were evaluated. The experimental design was an augmented block with four replicates, and Golden and Calimosa cultivars were the common treatment. Estimates of individual heritability were high for fruit length (FL) and weight (FW), moderate for fruit diameter (FD), and low for total soluble solids (TSS) and fruit firmness (FF). Considering FF and TSS as main traits for selection, genotypes of Calimosa-F2 population showed better performance to FF, but worse concerning TSS. It was selected 18.3% and 24.6% of plants from Tainung-F2 and Calimosa-F2 populations, respectively. Negative correlation between TSS and FF was not able to reduce the genetic gains. The segregating populations from Calimosa hybrid are more promising for the selection of papaya lines.

Selection of morpho-agronomic descriptors for characterization of papaya cultivars

This study was conducted to define a list of sufficient minimum descriptors to distinguish between papaya genotypes quickly and precisely. To this end, 30 quantitative and 21 multi-category descriptors related to plant characteristics, such as leaves, flowers, fruit and seeds were evaluated in 27 genotypes of papaya, including crops, local varieties and improved lines. The quantitative descriptors were subjected to principal components analyses using the Singh and direct selection methods, whereas a correlation analysis was conducted for the qualitative descriptors. Eighteen and fifteen quantitative descriptors were discarded by the Singh and direct selection methods, respectively. However, considering the simultaneous analyses of these methodologies, 60% of the descriptors were selected to maximize the total variation of the genotypes. Six of the multi-category descriptors were monomorphic, and two were highly correlated with other characteristics and were discarded. The minimum descriptors that were selected had high discrimination potentials when they were analyzed together. Thus, for the purposes of the protection of varieties and the classification of the genotypes of papaya, there were found to be 18 quantitative and 13 multi-category minimum descriptors that contributed significantly to the total variation and possessed low correlation with each other. The elimination of descriptors did not entail a loss of information. Those descriptors that contributed most significantly to the first three principal components were the stem diameters, fruit lengths and widths, inflorescence peduncle lengths, thickness of fruit skin, leaf widths, dry and fresh seed weights and ratio between fruit lengths and widths and between total soluble solids and total titratable acidities.

SELEÇÃO E RECOMENDAÇÃO DE VARIEDADES DE MAMOEIRO: AVALIAÇÃO DE LINHAGENS E HÍBRIDOS

The origin center of papaya is, very probably, the Northwest of South America, more precisely the Superior Amazon Basin - where the genetic diversity is maximum, what characterizes it as a typically tropical plant. Although Brazil is the largest world producer, the whole area of commercial production is planted exclusively with two groups of cultivars: Havai and Formosa, evidencing a narrow genetic base. This work had the objective to evaluate lineages and hybrids, adapted to different conditions, with emphasis to resistance to diseases, carrying out agronomic evaluation of the promising papaya genotypes, in order to identify those best adapted to different agroecosystems. The acessions of the Papaya Active Germplasm Bank (BAG-Papaya) presented a high genetic variability to weight, length and diameter of the fruits, allowing to be explored in programs of genetic improvement. In addition, the analysis of hybrid plant suggested the possibility of genetic changes in important commercial characters. From the evaluations of 125 accessions of the BAG - Papaya at Embrapa Cassava and Tropical Fruits, it was observed that in relation to the Phytophthora spp., the accessions CMF 001, CMF 053, CMF 062, CMF 081, CMF 089 are moderately tolerant, and the accessions CMF 002, CMF 007, CMF 033, CMF 060, CMF 065, CMF 070, CMF 071, CMF 083, CMF 101 have higher larger tolerance level. These accessions are being used in works of plant breeding, aiming to produce resistant or tolerant lineages to the fungi.

Identificação de microssatélites para o mamoeiro por meio da exploração do banco de dados de DNA

Microsatellites markers are a useful tool in much plant genetic analysis. Currently, few microsatellites loci have been reported in Carica papaya L.. Therefore, the objective of this study was accomplishing a search for microsatellites in the public available - GenBank / NCBI (National Center of Biotechnology Information), aiming the future use in molecular and genetic studies applied to genetic breeding. The sequences were collected from GenBank / NCBI in FASTA-formatted files and analyzed for the presence of microsatellites with a minimum of 20, 7 and 5 repetitions of mono-, di- and trinucleotides, respectively, and above of 4 repetitions for tetra- and pentanucleotides. The sequences with over 90% of similarity, were considered redundant and, therefore, eliminated of the analyses. A total of 44,591 sequences had been analyzed, of which 3,180 were not redundant, showing 3,947 microsatellites. Out of those, 3,587 were classified as perfect, 8 imperfects, 65 interrupted, 239 perfect-compounds, 8 imperfect-compounds and 40 interrupted-compounds. The dinucleotides and trinucleotides repetitions represented 65.7 and 14.4% of the whole analyzed sequences, respectively. Only the AT/TA motif represented 44.1% of the microsatellites sequences. The most common motifs of tri-, tetra- and pentanucleotides were AAT, AATT and TTTAA, respectively. In the available sequences it can be observed that the papaya genome has an average one microsatellite for every 5,65 kb.

Marcadores moleculares na predição do sexo em plantas de mamoeiro

O objetivo deste trabalho foi validar marcadores moleculares, previamente identificados como ligados ao sexo do mamoeiro, para utilizacao na selecao indireta em genotipos comerciais. Foram analisadas duas variedades do grupo Solo e dois hibridos do grupo Formosa, com utilizacao de 20 plantas por genotipo, quatro marcadores do tipo SCAR (Sequence Characterized Amplified Region) e um RAPD (Random Amplified Polymorphic DNA). O RAPD BC210 permitiu a identificacao de todas as plantas femininas e hermafroditas, o que revela grande potencial para ser usado na selecao assistida em alguns dos genotipos mais cultivados no Brasil. Os marcadores do tipo SCAR nao permitiram a identificacao correta do sexo dos genotipos, pois detectou-se a presenca de falso-positivos e falso-negativos nas analises.

Molecular characterization of papaya genotypes using AFLP markers

ABSTRACT - Due to the low genetic variability reported in the commercial plantations of papaya (Carica papaya L.), the objective of this study was analyze the genetic diversity of 32 genotypes including cultivars, landraces, inbred lines, and improved germplasm using the AFLP technique (Amplified Fragment Length Polymorphism). The genetic distance matrix was obtained using the Nei and Li genetic distance and clustering was performed using the unweighted pair-method with arithmetic mean (UPGMA). Using 11 combinations of EcoRI/MseI primers, 383 polymorphic bands were obtained. On average, 34.8 polymorphic bands were obtained per primer combination. Five clusters were formed. The traditional cultivar ‘Sunrise’ and the inbred line CMF-L30-08 were the closest genotypes, and the improved germplasm (CMF041) and landrace (CMF233) the most distant. The main papaya cultivars commercially grown in Brazil, as well as four inbred lines and three improved germplasm, were clustered together, however, were not grouped in the same branch. The genetic distance between the Sunrise and Golden cultivars was 0.329, and even arising from mutation and selection within the Sunrise variety, the Golden stores considerable genetic variability. Additional variability was observed in the inbred lines derived from papaya breeding program at Embrapa Cassava and Fruits.Index terms: papaya breeding, genetic resources, genetic diversity, Carica papaya L..

AVALIAÇÃO AGRONÔMICA DE LINHAGENS E HÍBRIDOS DE MAMOEIRO

ABSTRACTThis study aimed to evaluate the agronomic potential of papaya hybrids synthesized by Embrapa Cassava & Fruits, to identify and select genotypes with good agronomic characteristics, exploitable in the breeding program and direct use in the papaya production system. This study was carried out in the Experimental Field Sector of Embrapa Cassava & Fruits, Cruz das Almas - BA. It was evaluated 22 genotypes (eight lines, twelve hybrids and two witnesses: Sunrise Solo and Tainung no 1) in a randomized block design with four replications of six plants perplot, totalizing 528 plants. For most characters significant differences were observed at 1% and 5% probability, except for stem diameter (SD). The line L60 and H10.60 stood out with the lowest averages for plant height (PH) and insertion height of the first fruits (IHFF), and were not statistically different. Lines L10 and L72, and the hybrids H10.26, H10.60 and H10.72 showed higher averages of numbers of commercial fruits (NCF) than the witness Sunrise Solo. For yield, it was observed wide variability among treatments, with 75% of lines and hybrids overcame the witnesses. Over 50% of the genotypes showed soluble solids (SS) averages above 12 ° Brix. Aiming to associate favorable characteristics for development of new varieties, lines and hybrids that showed satisfactory behavior to the main characters were: L60 and H10.60 to IHFF and PH; L10, L72, H10.26, H10.60 and H10.72, for NCF; L10, H10.72, H26.72, H33.56 and H36.45, for productivity (PROD), and L26, L36, H10.26, H10.60 and H60.72, for SS.

Development and validation of minisatellite markers for Carica papaya

Whereas microsatellite markers are well described, there are few studies investigating minisatellites. Therefore, this study aimed to identify, characterize, and validate minisatellite loci for papaya (Carica papaya L.). The entire papaya genome, which covers 330 Mb, was used to mine minisatellites with motifs ranging from 6 to 500 bp, and at least six replicates and 82 loci were validated in a set of 24 accessions. A total of 1 730 minisatellite loci were identified, located in 695 sequences, with an average of one minisatellite every 156 kb. Variation in GC content ranged from 0.00 to 83.84 % with an average of 28.84 % indicating that these papaya minisatellites are AT rich. Motifs of up to 20 bases represented 71.45 % of the markers. In addition, the observed variation in the number of motif repeats was from 6 to 186 with an average of 9.27 per minisatellite. Independent of the classification, the frequency of minisatellites decreased with an increase in the number of repeating units. Among the validated loci, 48.78 % were found to be polymorphic, and the number of alleles (NA) ranged from two to seven with a mean of 3.10. The average polymorphic information content (PIC), expected heterozygosity (He), and observed heterozygosity (Ho) were 0.38, 0.43, and 0.11, respectively. According to genetic diversity parameters, such as NA, He, and PIC, no significant correlations were found among the size of motifs, the number of repeats, and the GC content of these minisatellites. This study clearly demonstrates the polymorphism of minisatellites and their potential use in detection of intraspecific genetic variations in C. papaya. The results will be useful when managing genetic resources and plant breeding.