This work was carried out with the objective of performing a molecular and aggressiveness characterization of F. solani and F. oxysporum f.sp. passiflorae collected in the Pantanal, Cerrado and Amazon biomes. We selected the most aggressive isolates for use in breeding programs aiming resistance to Collar Rot and Fusariosis. For inoculation of the isolates of F. oxysporum f.sp. passiflorae the washed root method was used. The molecular characterization of the isolates was carried out by partial sequencing of the Transcribed Internal Spacer of the rDNA region. The isolates of F. solani formed two distinct groups in relation to aggressiveness. Among all isolates, FSUNEMAT 40 and FSUNEMAT 46 were the most aggressive. The model with K=2 was taken as the best model to explain the genetic structure of the F. solani populations, with clear combinations of genes from both gene pools. There were three groups with respect to the aggressiveness of the isolates of F. oxysporum f.sp. passiflorae, with the isolated FOUNEMAT 22 being the most aggressive. In view of these results, the isolates of F. solani collected in P. edulis in the state of Mato Grosso presented a high molecular variability independent from the biome of origin, and this was also observed in the tests of aggressiveness. The results indicate the need to consider the molecular variability and the aggressiveness of the pathogens in the evaluation of genotypes of sour passion fruit in programs of selection of resistant cultivars.
ABSTRACT. This study aimed to evaluate the genetic variability of the teak germplasm bank, using morphological traits and inter-simple sequence repeat molecular markers. Thirty clones were evaluated in a randomized complete block design with three replicates, and each plot was composed of three plants. A joint analysis of quantitative and qualitative variables was performed using the Gower algorithm. Quantitative, qualitative, and molecular variables were analyzed simultaneously using the Ward-MLM procedure. There is genetic variability among the 30 teak genotypes studied, considering the quantitative, qualitative, and molecular variables by the Ward-MLM statistical procedure. Morphological traits used proved to be efficient for the study of genetic variability; however, it was not possible to compose a descriptor table for clonal teak genotypes based on the traits evaluated. The Gower method was efficient in discriminating the groups, demonstrating that the simultaneous analysis of qualitative and quantitative data is feasible and can allow greater efficiency in the knowledge of the variability among teak genotypes. The genotype 22 showed to be the most divergent compared to the other genotypes, except for the cluster of genotypes by the UPGMA method based on the Gower distance obtained by the Ward-MLM procedure, which formed a group with genotypes 9 and 30, in the morphological and molecular analyses and was grouped alone.
Fusariosis and base rot, caused by the fungi Fusarium oxysporum f. sp. passiflorae and F. solani, respectively, seriously damage the cultivation of sour passion fruit in Brazil. This work aims to obtain and evaluate F1 hybrids of Passiflora spp. wild plants resistant to fusariosis and base rot using genotypes of P. edulis (commercial species) and certify interspecific hybridizations using microsatellite markers. Hybridizations were performed using a P. edulis female parent and P. nitida and P. mucronata male parents for crosses aiming fusariosis resistance, and P. nitida, P. cincinnata and P. quadrangularis for hybridizations aiming tolerance to base rot. 35 microsatellite markers were used to confirm hybridization. The washed roots method was used for fusarium resistance tests and inoculation procedure with a mycelium disk fixed on a small wound on the plant stem for base rot. The interspecific hybridizations provided 49 potentially hybrid genotypes. Confirmation of hybridization by microsatellite marker was verified for 57% of the analyzed genotypes. The hybrids 115-1, 115-3, 115-4, 115-5, 115-6, 115-7, 115-9 and 128 are indicated as promising genotypes for a new stage of the breeding program. In the resistance evaluation of 13 F1 hybrids to F. oxysporum f. sp. passiflorae, the genotypes 142 and 143-2 were selected as the most resistant to continue the breeding program.
Brazil is the world's largest producer of passion fruit, however, the crop suffers from serious phytosanitary problems, as well as those caused by soil fungi. Thus, the objective of the present work was to estimate the genetic parameters and to select genotypes resistant to Fusarium solani species complex—FSSC in a segregating population from the first generation of backcross among P. edulis and interspecific hybrids, aiming at advancing generation in the genetic improvement program of passion fruit. The Interspecific Hybrid was used (IH) UNEMAT 142 resistant to colon rot, for generation advancement and to cultivate BRS Sol do Cerrado (Passiflora edulis Sims). In order to evaluate the resistance of the 27 genotypes of the first generation of backcrosses, inoculation with the FSUNEMAT 40 (F. solani) inoculum was performed. To estimate the components of variances, the method of maximum restricted likelihood (REML) was used and to select the best genotypes by the non-addicted linear prediction (BLUP). The variables that showed the highest heritability values were the survival period and the area under the lesion length expansion curve. The three families of backcrosses presented genotypes resistant to the fungus F. solani, however, by the methodology of mixed models REML/BLUP, only the genotypes BC1-22/1, BC1-22/2, BC1-22/3, BC1-22/4, BC1-22/6, BC1-22/7, BC1-113/3, BC1-113/7 and BC1-113/8, were selected to advance the generation of the UNEMAT passion fruit breeding program, therefore, they presented among the ten placed, mainly for the variable survival period (SP).
Teak (Tectona grandis Linn. f.) is considered one of the most expensive hardwoods in the world. The dispersion of the species over the years has taken the teak beyond its origin centers and little is known about the genetic origin and genetic variability. This study aimed to investigate the genetic diversity and population structure existing in a teak germplasm bank collection in Brazil. DNA was extracted from young leaves and each sample were genotyped by whole genome sequencing at 8x of coverage, the sequencing were aligned using the genome at NCBI, and SNPcalls and quality control were made. To study the population structure of the genotypes, Bayesian variational inference was used via fastStructure, the phylogenetic tree was based on the modified Euclidean distance and the clustering by the UPGMA hierarchical method. Genetic diversity was analyzed based on the pairwise genetic divergence (Fst) of Weir and Cockerham. Genotyping by sequencing resulted in a database of approximately 1.4 million of variations SNPs were used for analysis. It was possible to identify four subpopulations with genetic variability between and within the subpopulations, so this study made it possible to confirm the existence of genetic variability in teak, contrary to what was expected.
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