Shades of white: The Petunia long corolla tube clade evolutionary history.

Delimiting species is challenging in recently diverged species, and adaptive radiation is fundamental to understanding the evolutionary processes because it requires multiple ecological opportunities associated with adaptation to biotic and abiotic environments. The young Petunia genus (Solanaceae) is an excellent opportunity to study speciation because of its association with pollinators and unique microenvironments. This study evaluated the phylogenetic relationships among a Petunia clade species with different floral syndromes that inhabit several environments. We based our work on multiple individuals per lineage and employed nuclear and plastid phylogenetic markers and nuclear microsatellites. The phylogenetic tree revealed two main groups regarding the elevation of the distribution range, whereas microsatellites showed high polymorphism-sharing splitting lineages into three clusters. Isolation by distance, migration followed by new environment colonization, and shifts in floral syndrome were the motors for lineage differentiation, including infraspecific structuring, which suggests the need for taxonomic revision in the genus.

Insights into the evolutionary history of the most skilled tool-handling platyrrhini monkey: Sapajus libidinosus from the Serra da Capivara National Park.

Sapajus libidinosus members of the Pedra Furada group, living in the Serra da Capivara National Park, use stone tools in a wider variety of behaviors than any other living animal, except humans. To rescue the evolutionary history of the Caatinga S. libidinosus and identify factors that may have contributed to the emergence and maintenance of their tool-use culture, we conducted fieldwork seasons to obtain biological samples of these capuchin monkeys. UsingCYTBsequences, we show a discrete but constant population growth from the beginning of the Holocene to the present, overlapping the emergence of the Caatinga biome. Our habitat suitability reconstruction reports the presence of plants whose hard fruits, seeds, or roots are processed by capuchins using tools. TheS. libidinosusindividuals in the Caatinga were capable of dynamically developing and maintaining their autochthonous culture thanks to: a) cognitive capacity to generate and execute innovation under selective pressure; b) tolerance favoring learning and cultural inheritance; c) an unknown genetic repertoire that underpins the adaptive traits; d) a high degree of terrestriality; e) presence and abundance of natural resources, which makes some places "hot spots" for innovation, and cultural diversification within a relatively short time.

Transcriptomics analysis of Psidium cattleyanum Sabine (Myrtaceae) unveil potential genes involved in fruit pigmentation.

Psidium cattleyanum Sabine is an Atlantic Forest native species that presents some populations with red fruits and others with yellow fruits. This variation in fruit pigmentation in this species is an intriguing character that could be related to species evolution but still needs to be further explored. Our goal was to provide genomic information for these morphotypes to understand the molecular mechanisms of differences in fruit colour in this species. In this study, we performed a comparative transcriptome analysis of red and yellow morphotypes of P. cattleyanum, considering two stages of fruit ripening. The transcriptomic analysis performed encompassing leaves, unripe and ripe fruits, in triplicate for each morphotype. The transcriptome consensus from each morphotype showed 301,058 and 298,310 contigs from plants with yellow and red fruits, respectively. The differential expression revealed important genes that were involved in anthocyanins biosynthesis, such as the anthocyanidin synthase (ANS) and UDP-glucose:flavonoid-o-glucosyltransferase (UFGT) that were differentially regulated during fruit ripening. This study reveals stimulating data for the understanding of the pathways and mechanisms involved in the maturation and colouring of P. cattleyanum fruits and suggests that the ANS and UFGT genes are key factors involved in the synthase and pigmentation accumulation in red fruits.

Multiple markers, niche modelling, and bioregions analyses to evaluate the genetic diversity of a plant species complex.

BACKGROUND: The classification of closely related plants is not straightforward. These morphologically similar taxa frequently maintain their inter-hybridization potential and share ancestral polymorphisms as a consequence of their recent divergence. Under the biological species concept, they may thus not be considered separate species. The Petunia integrifolia complex is especially interesting because, in addition to the features mentioned above, its taxa share a pollinator, and their geographical ranges show multiple overlaps. Here, we combined plastid genome sequences, nuclear microsatellites, AFLP markers, ecological niche modelling, and bioregions analysis to investigate the genetic variability between the different taxa of the P. integrifolia complex in a comprehensive sample covering the entire geographical range of the complex. RESULTS: Results from molecular markers did not fully align with the current taxonomic classification. Niche modelling and bioregions analyses revealed that taxa were associated with different ecological constraints, indicating that the habitat plays an important role in preserving species boundaries. For three taxa, our analyses showed a mostly conserved, non-overlapping geographical distribution over time. However, for two taxa, niche modelling found an overlapping distribution over time; these taxa were also associated with the same bioregions. CONCLUSIONS: cpDNA markers were better able to discriminate between Petunia taxa than SSRs and AFLPs. Overall, our results suggest that the P. integrifolia complex represents a continuum of individuals from distant and historically isolated populations, which share some morphological traits, but are established in four different evolutionary lineages.

Molecular evolution analysis of WUSCHEL-related homeobox transcription factor family reveals functional divergence among clades in the homeobox region.

Gene families have been shown to play important roles in plant evolution and are associated with diversification and speciation. Genes of WUSCHEL-related homeobox family of transcription factors have important functions in plant development and are correlated with the appearance of evolutionary novelties. There are several published studies related to this family, but little is known about the relationships among the main clades in the phylogeny and the molecular evolution of the family. In this study, we obtained a well-resolved Bayesian phylogenetic tree establishing the relationships among the main clades and determining the position of Selaginella moellendorffii WOX genes. Moreover, a correlation was identified between the number of genes in the genomes and the events of whole-genome duplications. The intron-exon structure is more consistent across the modern clade, which appeared more recently in the WOX evolutionary history, and coincides with the development of higher complexity in plant species. No positive selection was detected among sites through the branches in the tree. However, with regard to the main clades, functional divergence among certain amino acids in the homeodomain region was found. Relaxed purifying selection could be the main driving force in the evolution of these genes and in agreement with some genes have been demonstrated to be functionally redundant.

High levels of genetic diversity and population structure in an endemic and rare species: implications for conservation.

The analysis of genetic structure and variability of isolated species is of critical importance in evaluating whether stochastic or human-caused factors are affecting rare species. Low genetic diversity compromises the ability of populations to evolve and reduces their chances of survival under environmental changes. Petunia secreta, a rare and endemic species, is an annual and heliophilous herb that is bee-pollinated and easily recognizable by its purple and salverform corolla. It was described as a new species of the Petunia genus in 2005. Few individuals of P. secreta have been observed in nature and little is known about this species. All the natural populations of P. secreta that were found were studied using 15 microsatellite loci, two intergenic plastid sequences and morphological traits. Statistical analysis was performed to describe the genetic diversity of this rare species and the results compared with those of more widespread and frequent Petunia species from the same geographic area to understand whether factors associated with population size could affect rare species of this genus. The results showed that despite its rarity, P. secreta presented high genetic diversity that was equivalent to or even higher than that of widespread Petunia species. It was shown that this species is divided into two evolutionary lineages, and the genetic differentiation indices between them and other congeneric species presented different patterns. The major risk to P. secreta maintenance is its rarity, suggesting the necessity of a preservation programme and more biological and evolutionary studies that handle the two evolutionary lineages independently.

Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species.

Identifying the genetic basis of speciation is critical for understanding the evolutionary history of closely related wild species. Recently diverged species facilitate the study of speciation because many genetic and morphological characteristics are still shared by the organisms under study. The Petunia genus grows in South American grasslands and comprises both recently diverged wild species and commercial species. In this work, we analysed two closely related species: Petunia exserta, which has a narrow endemic range and grows exclusively in rocky shelters, and Petunia axillaris, which is widely distributed and comprises three allopatric subspecies. Petunia axillaris ssp. axillaris and P. exserta occur in sympatry, and putative hybrids between them have been identified. Here, we analysed 14 expressed sequence tag-simple sequence repeats (EST-SSRs) in 126 wild individuals and 13 putative morphological hybrids with the goals of identifying differentially encoded alleles to characterize their natural genetic diversity, establishing a genetic profile for each taxon and to verify the presence of hybridization signal. Overall, 143 alleles were identified and all taxa contained private alleles. Four major groups were identified in clustering analyses, which indicated that there are genetic distinctions among the groups. The markers evaluated here will be useful in evolutionary studies involving these species and may help categorize individuals by species, thus enabling the identification of hybrids between both their putative taxa. The individuals with intermediate morphology presented private alleles of their both putative parental species, although they showed a level of genetic mixing that was comparable with some of the individuals with typical P. exserta morphology. The EST-SSR markers scattered throughout the Petunia genome are very efficient tools for characterizing the genetic diversity in wild taxa of this genus and aid in identifying interspecific hybrids based on the presence of private alleles. These properties indicate that these markers will be helpful tools in evolutionary studies.

Molecular insights into the purple-flowered ancestor of garden petunias.

PREMISE OF THE STUDY: The garden petunia is derived from Petunia axillaris (white flowered) and a purple-flowered species in the P. integrifolia group; it is still unclear which purple-flowered species was used in the initial crosses. This widely cultivated hybrid is an ideal model for different areas of scientific inquiry. METHODS: We analyzed three taxa of the P. integrifolia group considered to be the most probable parental candidates, along with a random sample of garden petunia representatives that were selected for their genetic variability. We used cpDNA trnH-psbA and trnS-trnG haplotypes and seven nuclear microsatellites in a population approach to investigate the genetic variability. This is the first time information from plastid DNA sequences and nuclear microsatellites has been combined to infer evolutionary relationships in these taxa. KEY RESULTS: Our results suggest that P. interior is the purple ancestor of garden petunias, and we postulate that the initial crosses must have been between both parents as a mother plant. CONCLUSIONS: Our work will contribute to the clarification of the evolutionary relationships among the Petunia ×hybrida and P. integrifolia taxa group and could be useful in breeding programs to transfer desired traits from wild to cultivated species.

MAEWEST expression in flower development of two petunia species.

Changes in flower morphology may influence the frequency and specificity of animal visitors. In Petunia (Solanaceae), adaptation to different pollinators is one of the factors leading to species diversification within the genus. This study provides evidence that differential expression patterns of MAWEWEST (MAW) homologs in different Petunia species may be associated with adaptive changes in floral morphology. The Petunia × hybrida MAW gene belongs to the WOX (WUSCHEL-related homeobox) transcription factor family and has been identified as a controller of petal fusion during corolla formation. We analyzed the expression patterns of P. inflata and P. axillaris MAW orthologs (PiMAW and PaMAW, respectively) by reverse transcriptase polymerase chain reaction (RT-PCR), reverse transcription-quantitative PCR (qRT-PCR) and in situ hybridization in different tissues and different developmental stages of flowers in both species. The spatial expression patterns of PiMAW and PaMAW were similar in P. inflata and P. axillaris. Nevertheless, PaMAW expression level in P. axillaris was higher during the late bud development stage as compared to PiMAW in P. inflata. This work represents an expansion of petunia developmental research to wild accessions.