Daniela Sandra Tosto

Bio: Daniela Sandra Tosto is an academic researcher from International Trademark Association. The author has contributed to research in topics: Helicoverpa & Genetic structure. The author has an hindex of 7, co-authored 9 publications receiving 198 citations. Previous affiliations of Daniela Sandra Tosto include Facultad de Ciencias Exactas y Naturales.

Molecular phylogeny and diversification history of Prosopis (Fabaceae: Mimosoideae)

Abstract: The genus Prosopis is an important member of arid and semiarid environments around the world. To study Prosopis diversification and evolution, a combined approach including molecular phylogeny, molecular dating, and character optimization analysis was applied. Phylogenetic relationships were inferred from five different molecular markers (matK-trnK, trnL-trnF, trnS-psbC, G3pdh, NIA). Taxon sampling involved a total of 30 Prosopis species that represented all Sections and Series and the complete geographical range of the genus. The results suggest that Prosopis is not a natural group. Molecular dating analysis indicates that the divergence between Section Strombocarpa and Section Algarobia plus Section Monilicarpa occurred in the Oligocene, contrasting with a much recent diversification (Late Miocene) within each of these groups. The diversification of the group formed by species of Series Chilenses, Pallidae, and Ruscifoliae is inferred to have started in the Pliocene, showing a high diversification rate. The moment of diversification within the major lineages of American species of Prosopis is coincident with the spreading of arid areas in the Americas, suggesting a climatic control for diversification of the group. Optimization of habitat parameters suggests an ancient occupation of arid environments by Prosopis species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 621–640.

The key role of the largest extant Neotropical frugivore (Tapirus terrestris) in promoting admixture of plant genotypes across the landscape

Abstract: The historical and contemporary loss of large-bodied frugivores has disrupted many plant-disperser mutualisms, with potentially profound consequences for plants. Although several aspects of seed dispersal by megafrugivores have already been examined, the role of these species in promoting seed-mediated gene flow has remained unexplored. We evaluated the role of the Amazonian tapir (Tapirus terrestris), the largest Neotropical frugivore, in shaping plant genetic structure through seed-mediated gene flow. We used microsatellites to analyze the genetic patterns of Syagrus romanzoffiana seedlings recruited in tapir latrines and around conspecific adult palms, the two sites where seeds and seedlings are most frequently found in this species. While the genetic diversity of seedlings was rather similar in both sites, the kinship structure was substantially weaker in latrines. Most seedlings recruited around adult palms were half- or full-sibs originating from those adults. In contrast, seedlings recruited in latrines came from several (>5, on average) contributing mothers other than the nearest adult (95%) and were mostly non-sibs (72%). Kinship patterns indicated that tapir-mediated dispersal promotes the admixture of genotypes across space. Also, our results suggested that genetic diversity and the number of contributing mothers in latrines increase with the number of fruiting adults visited by tapirs before defecating and with the accumulation of feces over time. We provide evidence of the relevance of tapirs in mobilizing maternal progenies (and genotypes) across the landscape and recruiting clusters of unrelated seedlings. This study suggests a key role for plant–megafrugivore interactions in seed-mediated gene flow and emphasizes the importance of preserving such mutualisms. Resumen La perdida historica y contemporanea de los frugivoros de gran porte ha suprimido muchos mutualismos planta-dispersor, con consecuencias potencialmente profundas para las plantas. Si bien varios aspectos de la dispersion de semillas por megafrugivoros ya han sido examinados, el rol de estas especies en promover el flujo genico mediado por semillas ha permanecido inexplorado. Evaluamos el rol del tapir amazonico (Tapirus terrestris), el mayor frugivoro Neotropical, en moldear la estructura genetica de las plantas a traves del flujo genico mediado por semillas. Usamos microsatelites para analizar los patrones geneticos de plantulas de Syagrus romanzoffiana reclutadas en letrinas de tapir y alrededor de palmeras conespecificas adultas, los dos sitios donde las semillas y las plantulas son mas frecuentemente halladas en esta especie. Mientras que la diversidad genetica de las plantulas fue bastante similar en ambos sitios, la estructura de parentesco fue sustancialmente mas debil en las letrinas. La mayoria de las plantulas reclutadas alrededor de palmeras adultas eran hermanas o medio-hermanas descendientes de dicho adulto. En contraste, las plantulas reclutadas en letrinas provenian de varias (> 5, en promedio) madres contribuyentes, distintas del adulto mas cercano (95%), y en su mayoria no eran hermanas (72%). Los patrones de parentesco indicaron que la dispersion mediada por tapires promueve la mezcla de los genotipos a traves del espacio. Ademas, nuestros resultados sugirieron que la diversidad genetica y el numero de madres contribuyentes en las letrinas aumenta con el numero de adultos con fruto visitados por los tapires antes de defecar y con la acumulacion de heces en el tiempo. Presentamos evidencias de la relevancia de los tapires en el movimiento de progenies maternas (y genotipos) a traves del paisaje y el reclutamiento de grupos de plantulas no emparentadas. Este estudio sugiere un rol clave de las interacciones plantas-megafrugivoros en el flujo genico mediado por semillas y enfatiza la importancia de preservar tales mutualismos.

Early genetic consequences of defaunation in a large-seeded vertebrate-dispersed palm (Syagrus romanzoffiana).

Abstract: Plant populations are seriously threatened by anthropogenic habitat disturbance. In particular, defaunation may disrupt plant-disperser mutualisms, thus reducing levels of seed-mediated gene flow and genetic variation in animal-dispersed plants. This may ultimately limit their adaptive potential and ability to cope with environmental change. Tropical forest remnants are typically deprived of medium to large vertebrates upon which many large-seeded plants rely for accomplishing effective seed dispersal. Our main goal was to examine the potential early genetic consequences of the loss of large vertebrates for large-seeded vertebrate-dispersed plants. We compared the genetic variation in early-stage individuals of the large-seeded palm Syagrus romanzoffiana between continuous protected forest and nearby partially defaunated fragments in the Atlantic Forest of South America. Using nine microsatellites, we found lower allelic richness and stronger fine-scale spatial genetic structure in the disturbed area. In addition, the percentage of dispersed recruits around conspecific adults was lower, although not significantly, in the disturbed area (median values: 0.0 vs 14.4%). On the other hand, no evidence of increased inbreeding or reduced pollen-mediated gene flow (selfing rate and diversity of pollen donors) was found in the disturbed area. Our findings are strongly suggestive of some early genetic consequences resulting from the limitation in contemporary gene flow via seeds, but not pollen, in defaunated areas. Plant-disperser mutualisms involving medium–large frugivores, which are seriously threatened in tropical systems, should therefore be protected to warrant the maintenance of seed-mediated gene flow and genetic diversity in large-seeded plants.

Population genetics structure of glyphosate-resistant Johnsongrass (Sorghum halepense L. Pers) does not support a single origin of the resistance.

Abstract: Single sequence repeats (SSR) developed for Sorghum bicolor were used to characterize the genetic distance of 46 different Sorghum halepense (Johnsongrass) accessions from Argentina some of which have evolved toward glyphosate resistance. Since Johnsongrass is an allotetraploid and only one subgenome is homologous to cultivated sorghum, some SSR loci amplified up to two alleles while others (presumably more conserved loci) amplified up to four alleles. Twelve SSR providing information of 24 loci representative of Johnsongrass genome were selected for genetic distance characterization. All of them were highly polymorphic, which was evidenced by the number of different alleles found in the samples studied, in some of them up to 20. UPGMA and Mantel analysis showed that Johnsongrass glyphosate-resistant accessions that belong to different geographic regions do not share similar genetic backgrounds. In contrast, they show closer similarity to their neighboring susceptible counterparts. Discriminant Analysis of Principal Components using the clusters identified by K-means support the lack of a clear pattern of association among samples and resistance status or province of origin. Consequently, these results do not support a single genetic origin of glyphosate resistance. Nucleotide sequencing of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) encoding gene from glyphosate-resistant and susceptible accessions collected from different geographic origins showed that none presented expected mutations in aminoacid positions 101 and 106 which are diagnostic of target-site resistance mechanism.

Contemporaneous and recent radiations of the world's major succulent plant lineages

Abstract: The cacti are one of the most celebrated radiations of succulent plants. There has been much speculation about their age, but progress in dating cactus origins has been hindered by the lack of fossil data for cacti or their close relatives. Using a hybrid phylogenomic approach, we estimated that the cactus lineage diverged from its closest relatives ≈35 million years ago (Ma). However, major diversification events in cacti were more recent, with most species-rich clades originating in the late Miocene, ≈10-5 Ma. Diversification rates of several cactus lineages rival other estimates of extremely rapid speciation in plants. Major cactus radiations were contemporaneous with those of South African ice plants and North American agaves, revealing a simultaneous diversification of several of the world's major succulent plant lineages across multiple continents. This short geological time period also harbored the majority of origins of C(4) photosynthesis and the global rise of C(4) grasslands. A global expansion of arid environments during this time could have provided new ecological opportunity for both succulent and C(4) plant syndromes. Alternatively, recent work has identified a substantial decline in atmospheric CO(2) ≈15-8 Ma, which would have strongly favored C(4) evolution and expansion of C(4)-dominated grasslands. Lowered atmospheric CO(2) would also substantially exacerbate plant water stress in marginally arid environments, providing preadapted succulent plants with a sharp advantage in a broader set of ecological conditions and promoting their rapid diversification across the landscape.

The evolutionary origins of pesticide resistance.

Abstract: Durable crop protection is an essential component of current and future food security. However, the effectiveness of pesticides is threatened by the evolution of resistant pathogens, weeds and insect pests. Pesticides are mostly novel synthetic compounds, and yet target species are often able to evolve resistance soon after a new compound is introduced. Therefore, pesticide resistance provides an interesting case of rapid evolution under strong selective pressures, which can be used to address fundamental questions concerning the evolutionary origins of adaptations to novel conditions. We ask: (i) whether this adaptive potential originates mainly from de novo mutations or from standing variation; (ii) which pre-existing traits could form the basis of resistance adaptations; and (iii) whether recurrence of resistance mechanisms among species results from interbreeding and horizontal gene transfer or from independent parallel evolution. We compare and contrast the three major pesticide groups: insecticides, herbicides and fungicides. Whilst resistance to these three agrochemical classes is to some extent united by the common evolutionary forces at play, there are also important differences. Fungicide resistance appears to evolve, in most cases, by de novo point mutations in the target-site encoding genes; herbicide resistance often evolves through selection of polygenic metabolic resistance from standing variation; and insecticide resistance evolves through a combination of standing variation and de novo mutations in the target site or major metabolic resistance genes. This has practical implications for resistance risk assessment and management, and lessons learnt from pesticide resistance should be applied in the deployment of novel, non-chemical pest-control methods.

Legume phylogeny and classification in the 21st century: Progress, prospects and lessons for other species-rich clades

Abstract: The Leguminosae, the third-largest angiosperm family, has a global distribution and high ecological and economic importance We examine how the legume systematic research community might join forces to produce a comprehensive phylogenetic estimate for the ca 751 genera and ca 19,500 species of legumes and then translate it into a phylogeny-based classification We review the current state of knowledge of legume phylogeny and highlight where problems lie, for example in taxon sampling and phylogenetic resolution We review approaches from bioinformatics and next-generation sequencing, which can facilitate the production of better phylogenetic estimates Finally, we examine how morphology can be incorporated into legume phylogeny to address issues in comparative biology and classification Our goal is to stimulate the research needed to improve our knowledge of legume phylogeny and evolution; the approaches that we discuss may also be relevant to other species-rich angiosperm clades

Cellulose and hemicellulose decomposition by forest soil bacteria proceeds by the action of structurally variable enzymatic systems.

Abstract: Evidence shows that bacteria contribute actively to the decomposition of cellulose and hemicellulose in forest soil; however, their role in this process is still unclear. Here we performed the screening and identification of bacteria showing potential cellulolytic activity from litter and organic soil of a temperate oak forest. The genomes of three cellulolytic isolates previously described as abundant in this ecosystem were sequenced and their proteomes were characterized during the growth on plant biomass and on microcrystalline cellulose. Pedobacter and Mucilaginibacter showed complex enzymatic systems containing highly diverse carbohydrate-active enzymes for the degradation of cellulose and hemicellulose, which were functionally redundant for endoglucanases, β-glucosidases, endoxylanases, β-xylosidases, mannosidases and carbohydrate-binding modules. Luteibacter did not express any glycosyl hydrolases traditionally recognized as cellulases. Instead, cellulose decomposition was likely performed by an expressed GH23 family protein containing a cellulose-binding domain. Interestingly, the presence of plant lignocellulose as well as crystalline cellulose both trigger the production of a wide set of hydrolytic proteins including cellulases, hemicellulases and other glycosyl hydrolases. Our findings highlight the extensive and unexplored structural diversity of enzymatic systems in cellulolytic soil bacteria and indicate the roles of multiple abundant bacterial taxa in the decomposition of cellulose and other plant polysaccharides.