Biology subjects

de Oliveira, F. A.

Publications and source records attributed to de Oliveira, F. A..

4 recordsLinked to original sources

bioRxiv2022

Genetic Diversity, Population Structure and Parentage Analysis in Brazilian Grapevine Hybrids after Half a Century of Genetic Breeding

In the 1940s, the Agronomic Institute of Campinas (IAC) started a grapevine breeding program to develop new cultivars adapted to the tropical and subtropical regions of Brazil. More than 2,000 crosses were carried out over 50 years, using 850 varieties as parents. However, among the thousands of hybrids developed by the program, only 130 are still maintained in the IAC grapevine germplasm collection. Little is known about their genetic makeup and usefulness for current breeding programs. In this study, we genotyped 130 Brazilian grape hybrids at 21 polymorphic microsatellite markers to evaluate the genetic diversity and population structure of the hybrids and verified their disclosed pedigrees. The results showed that the hybrid collection is highly diverse, with an expected heterozygosity (HE) of 0.80 and an observed heterozygosity (Ho) of 0.78. Strong structure in three subgroups based mainly on the usage and combination of parental groups was revealed by STRUCTURE software and confirmed by discriminant analysis of principal components (DAPC). Through molecular profiling analysis, fourteen synonyms, one homonym and one duplicate were identified. Parentage analysis confirmed 24 full parentages, as well as 33 half-kinships. In addition, 18 pedigrees were invalidated, and seven mislabeling events were identified. No compatible parent was identified for 33% of the IAC hybrids, highlighting severe genetic erosion in the IAC germplasm. The molecular characterization of the breeding hybrid bank collection contributes to our understanding of the genetic basis of the varieties, guiding the efficient utilization of available genetic diversity. Together, our results could be applied to other breeding programs and assist in the selection of parents, management of the breeding collection, and conservation of grapevine genetic resources.

molecular biology↗

bioRxiv2021

The anterior cingulate cortex and its role in controlling contextual fear memory to predatory threats.

Predator exposure is a life-threatening experience and elicits learned fear responses to the context in which the predator was encountered. The anterior cingulate area (ACA) occupies a pivotal position in a cortical network responsive to predatory threats, and it exerts a critical role in processing fear memory. Ours results revealed that the ACA is involved in both the acquisition and expression of contextual fear to predatory threat. Overall, the ACA can provide predictive relationships between the context and the predator threat and influences fear memory acquisition through projections to the basolateral amygdala and perirhinal region and the expression of contextual fear through projections to the dorsolateral periaqueductal gray. Our results expand previous studies based on classical fear conditioning and open interesting perspectives for understanding how the ACA is involved in processing contextual fear memory to ethologic threatening conditions that entrain specific medial hypothalamic fear circuits (i.e., predator- and conspecific-responsive circuits).

neuroscience↗

bioRxiv2020

Genetic structure and molecular diversity of Brazilian grapevine germplasm: management and use in the breeding programs

The management of germplasm banks is complex, especially when many accessions are involved. Microsatellite markers are an efficient tool for assessing the genetic diversity of germplasm collections, optimizing their use in breeding programs. This study genetically characterizes a large collection of 410 grapevine accessions maintained at the Agronomic Institute of Campinas (IAC) (Brazil). The accessions were genotyped with 17 highly polymorphic microsatellite markers. Genetic data were analyzed to determine the genetic structure of the germplasm, quantify its allelic diversity, suggest the composition of a core collection, and discover cases of synonymy, duplication, and misnaming. A total of 304 alleles were obtained, and 334 unique genotypes were identified. The molecular profiles of 145 accessions were confirmed according to the literature and databases, and the molecular profiles of more than 100 genotypes were reported for the first time. The analysis of the genetic structure revealed different levels of stratification. The primary division was between accessions related to Vitis vinifera and V. labrusca, followed by their separation from wild grapevine. A core collection of 120 genotypes captured 100% of all detected alleles. The accessions selected for the core collection may be used in future phenotyping efforts, in genome association studies, and for conservation purposes. Genetic divergence among accessions has practical applications in grape breeding programs, as the choice of relatively divergent parents will maximize the frequency of progeny with superior characteristics. Together, our results can enhance the management of grapevine germplasm and guide the efficient exploitation of genetic diversity to facilitate the development of new grape cultivars for fresh fruits, wine, and rootstock.

molecular biology↗

bioRxiv2019

High-resolution Linkage Map with Allele Dosage Allows the Identification of an Apomixis Region and Complex Traits in Guinea Grass (Megathyrsus maximus)

Forage grasses are mainly used in animal feed to fatten cattle and dairy herds. Among tropical forage crops that reproduce by seeds, guinea grass (Megathyrsus maximus) is considered one of the most productive. This species has several genomic complexities, such as autotetraploidy and apomixis, due to the process of domestication. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information about the genetic architecture of traits that are important for the breeding of M. maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map ten quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and apomixis locus by using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

plant biology↗