Giancarlo Conde Xavier Oliveira

Genetic structure of Brazilian wild rice (Oryza glumaepatula Steud., Poaceae) populations analyzed using microsatellite markers

Knowledge of the genetic structure and diversity of natural populations is important in developing strategies for in situ and ex situ conservation. We used eight microsatellite loci to estimate genetic structure and investigate within and between population genetic variation in eleven Brazilian wild rice (Oryza glumaepatula) populations. The study showed the following genetic diversity parameters: average number of 3.1 alleles per locus; 77.3% polymorphic loci; 0.091 observed heterozygosity and 0.393 gene diversity. F-statistics detected by microsatellite loci were: FST = 0.491 (and RST = 0.608), FIS = 0.780 and FIT = 0.888. No population was in Hardy-Weinberg equilibrium. The estimated apparent outcrossing rate (0.143) indicated a predominance of self-fertilization. The gene flow values were low (Nm = 0.259 and 0.161 for FST and RST, respectively). Populations were spatially structured but without a correlation between genetic and geographic distances. Five populations (PG-4, PG-2, PU-1, SO-4, NE-18) were identified as priorities for conservation strategies. Populations from the Amazon biome showed heterogeneity with respect to intrapopulation diversity. The high level of genetic differentiation between populations and the high number of private alleles suggested that sampling should be carried out on a large number of O. glumaepatula populations for ex situ conservation purposes.

Morphoagronomic genetic diversity in american wild rice species

To characterize the genetic variability among species and populations of South American wild rice, eleven populations of Oryza glumaepatula, seven of O. grandiglumis, four of O. latifolia and one of O. alta, from Brazil and Argentina, were evaluated. A greenhouse experiment was conducted in completely randomized blocks with 23 treatments. Twenty morphoagronomic traits were assessed. Univariate analyses were performed with 16 quantitative traits with the partitioning of populations within species. Significant differences (p<0.001) between species were observed for all the traits as well as among populations within the species. The most variable was O. glumaepatula followed by O. latifolia. Multivariate discriminant canonical and cluster analyses confirmed the separation of the highly diverse O. glumaepatula populations from the tetraploid species, and the high genetic variation among O. latifolia populations. Morphological differences among the three tetraploid species seemed to be enough to ascribe them at least the condition of species in statu nascendi.

Allelic diversity in populations of Solanum lycocarpum A. St.-Hil (Solanaceae) in a protected area and a disturbed environment

This study aimed to compare the genetic diversity of populations of Solanum lycocarpum A.St.-Hil between natural and human disturbed environments, with the assumption that protected areas have greater genetic diversity than disturbed areas. For this study, two populations were sampled in Goias State, Brazil. One was located in a conservation unit, Serra de Caldas Novas State Park, in the Caldas Novas municipality. The other was located in a pasture area in the municipality of Morrinhos. The two populations are 41 km apart. We sampled 60 individuals from each population, which were genotyped with five microsatellite loci (SSR). The highest number of alleles was recorded in the population of the conservation unit, where we found 11 exclusive and five rare alleles. In the disturbed area, we recorded only three exclusive alleles and one rare allele. Although we did not observe significant inbreeding in these populations, genetic divergence between them was high (GST (Hedrick)=0.147 =0.147) for a species with long distance seed dispersal. The results corroborate the hypothesis that the population in the less disturbed area harbors greater allelic diversity. They also confirm the effectiveness of using protected areas to preserve the genetic diversity of the species.

When and how could common gardens be useful in the ecological restoration of long-lived tropical plants as an aid to the selection of seed sources?

Background: The identification of genetic divergence among provenances is essential for designing seed zones for ecological restoration, but this is neither easy nor cheap, especially where tropical trees are concerned. Aims: In this study we sought to investigate the effectiveness of common garden and short-term reciprocal transplant experiments to identify genetic divergence in populations of Queen palm (Syagrus romanzoffiana). Methods: Seed harvesting was carried out in south-eastern Brazil, in natural remnants of seasonally dry forest, restinga and cerradão. Under common garden conditions, we examined the length of the cotyledonary petiole of three-month-old seedlings, and important sapling traits of 10-month-old nursery-grown individuals of the three above-mentioned seed provenances. Additionally, reciprocal transplants were carried out during 10 months for seasonally dry forest and cerradão seed lots. Results: In the common garden experiments, restinga seedlings had significantly shorter cotyledonary petioles, and cerradão saplings showed ca. 40% higher values for root, leaf blade, shoot and total dry mass, while saplings did not express genetic differences in reciprocal transplants, which is one of the four possible combined outcomes discussed here. Conclusions: Common garden experiments with long-lived tropical plant species used in ecological restoration can be advantageously used to improve the quality of the seed sources for restoration projects by detecting genetic divergence with a possible relation to local adaptation.

Interspecific xenia and metaxenia in seeds and fruits of tomato

Xenia, the transmission of traits from the pollinizer to the females tissues, is a phenomenon hitherto unknown in tomatoes. Here, we describe xenia effects on the seeds and fruits of Solanum lycopersicum, the tomato, elicited by S. galapagense. The wild tomatoes, such as S. galapagense, have highly pilose fruit surface and minute seeds, unlike the domesticated species. Crossings between S. galapagense (pollinizer) and two large-seeded, glabrous cultivars of S. lycopersicum (females) tested the formers ability to raise the trichome density and trichome-to-1000-cell ratio and to reduce the seed weight in the latters fruits. Selfed fruits of the two cultivars, Micro-Tom and Pusa Ruby, were compared to the crossed fruits. The pollen of S. galapagense was able to raise pilosity and to reduce seed weight in the crossed fruits of both cultivars, but with different magnitudes: seed reduction was more intense in Pusa Ruby, while pilosity increase was greater in Micro-Tom, both of which characterize xenia. Pilosity increase is not completely dependent on variation in epidermal cell density, which displayed no xenia effect. The difference between the maternal cultivars in the magnitude of pilosity increase may be due to the higher dilution of a putative male chemical signal (either hormone or RNA) in the larger fruits of Pusa Ruby. However, one cannot use the signal diffusion hypothesis to explain the xenia effects on seed weight.

Evolution of methodology for the study of adaptability and stability in cultivated species.

The GxE interaction only became widely discussed from evolutionary studies and evaluations of the causes of behavioral changes of species cultivated in environments. In the last 60 years, several methodologies for the study of adaptability and stability of genotypes in multiple environments trials were developed in order to assist the breeders choice regarding which genotypes are more stable and which are the most suitable for the crops in the most diverse environments. The methods that use linear regression analysis were the first to be used in a general way by breeders, followed by multivariate analysis methods and mixed models. The need to identify the genetic and environmental causes that are behind the GxE interaction led to the development of new models that include the use of covariates and which can also include both multivariate methods and mixed modeling. However, further studies are needed to identify the causes of GxE interaction as well as for the more accurate measurement of its effects on phenotypic expression of varieties in competition trials carried out in genetic breeding programs.

Biology and Genetics of Reproductive Systems

Chapter 2 will discuss the biology and genetics of asexual and sexual plant reproduction. In relation to the asexual system, special attention will be given to the apomictic reproduction, where we will point out aspects of this system, as well as details of the knowledge about mechanisms and genes involvement. Regarding the sexual reproduction system, we will discuss details of this reproductive mode, the life cycle of plants, the gametophytic and sporophytic generation, as additionally to the control of genes in reproductive organs. Subsequently, aspects of the mechanisms that promote allogamy, selfing and mixed mating will be presented.

Evolution of Plants with Emphasis on Its Reproduction Form

Chapter 1 of this book discusses the evolution of plants from the Pre-Cambrian era considering the starting time of alternation of generations. In the Paleozoic and Mesozoic eras, we will discuss the transitions from homospory to heterospory and the formation of the egg cell and the pollen grain as well as the evolution of seed plants. At the end of this chapter we will discuss the evolution of the angiosperms (flowering plants) and the sexuality transitions and the reproductive strategies. Also, the evolution of the unisexuality, self-incompatibility systems, selfing, and mixed mating systems will be discussed considering their evolutionary implications.

Phenotypic plasticity and local adaptation favor range expansion of a Neotropical palm

Abstract One of the most intriguing questions in plant ecology is which evolutionary strategy allows widely distributed species to increase their ecological range and grow in changing environmental conditions. Phenotypic plasticity and local adaptations are major processes governing species range margins, but little is known about their relative contribution for tree species distribution in tropical forest regions. We investigated the relative role of phenotypic plasticity and local adaptation in the ecological distribution of the widespread palm Euterpe edulis in the Brazilian Atlantic Forest. Genetic sampling and experiments were performed in old‐growth remnants of two forest types with higher (Seasonal Semideciduous Forests vs. Submontane Rainforest) and lower biogeographic association and environmental similarities (Submontane Rainforest vs. Restinga Forest). We first assessed the molecular genetic differentiation among populations, focusing on the group of loci potentially under selection in each forest, using single‐nucleotide polymorphism (SNPs) outliers. Further, we looked for potential adaptive divergence among populations in a common garden experiment and in reciprocal transplants for two plant development phases: seedling establishment and sapling growth. Analysis with outlier loci indicated that all individuals from the Semideciduous Forest formed a single group, while another group was formed by overlapping individuals from Submontane Rainforest and Restinga Forest. Molecular differentiation was corroborated by reciprocal transplants, which yielded strong evidence of local adaptations for seedling establishment in the biogeographically divergent Rainforest and Semideciduous Forest, but not for Restinga Forest and Submontane Rainforest. Phenotypic plasticity for palm seedling establishment favors range expansion to biogeographically related or recently colonized forest types, while persistence in the newly colonized ecosystem may be favored by local adaptations if climatic conditions diverge over time, reducing gene flow between populations. SNPs obtained by next‐generation sequencing can help exploring adaptive genetic variation in tropical trees, which impose several challenges to the use of reciprocal transplants.

MT BB: tomato cultivar for practical classes of plant genetics and breeding

MT BB cultivar originated from a backcross program which aimed at adding two recessive mutations that alter leaf architecture (potato leaf - c) and flower color (white flower - wf) to Micro-Tom cultivar, which is a tomato miniature. MT BB was developed for use in practical classes of genetics and breeding in both undergraduate and graduate courses.