Paspalum L. is a genus of the Poaceae family, with many species serving as well-adapted forage plants in subtropical climates and continuous grazing systems. However, Claviceps paspali, an ascomycete of the order Hypocreales, represents a major threat to the Paspalum species. This fungus induces ergot disease, characterized by the replacement of infected flower seeds with sclerotia, which adversely affects seed production and animal health through mycotoxin production. Although ergot disease is reported in many countries, no totally resistant Paspalum cultivars have been reported for commercial use. This study comparatively evaluated disease development in six Paspalum species under greenhouse conditions with three specific isolates of C. paspali, along with field trials. In addition, field isolates of C. paspali were analyzed for phenotypic characteristics and phylogenetic relationships. Greenhouse evaluation revealed variable susceptibility among Paspalum species, with P. malacophyllum, P. notatum, and P. umbrosum being the most resistant. In field trials P. dilatatum showed the highest severity index, and P. umbrosum and P. malacophyllum were less affected. The phenotypic characterization of 22 C. paspali isolates showed variability in pigmentation and growth rates, with potato dextrose agar being the culture medium in which the highest growth rate was observed. Phylogenetic analysis of the isolates identified two well-supported lineages between C. paspali species. This research reports an ergot resistance gradient among Paspalum species, identifying genuine sources of resistance. In addition, virulent isolates of C. paspali potentially useful for rapid screening of accessions or crosses in Paspalum breeding programs were identified.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Paspalum notatum Flüggé is a subtropical grass native from the Americas and one of the main components of the subtropical South American grasslands. Although P. notatum exhibits a high forage productivity and persistence, some limitations are observed in the species, such as forage quality due to high lignin content. The development of efficient tissue culture and plant transformation protocols in cultivars for forage production are necessary to embrace novel genetic improvement through transgenesis and genome editing. Efficient regeneration and transformation systems for many plant species can be hampered by genotype dependency, which can only be determined through extensive laboratory testing and evaluation. In this study, various factors extracted from protocols have been evaluated to establish efficient somatic embryogenesis, plant regeneration, and genetic transformation in apomictic initial variety INIA Sepé. Optimal somatic embryogenesis and regeneration from explant sources, such as mature seeds and meristematic tissue derived from in vitro propagated tillers, ranged between 79 and 88

Eucalyptus globulus Labill. is of great interest to the pulp industry. However, the species is highly susceptible to leaf spot caused by Teratosphaeria nubilosa and has a low rooting capacity. In order to overcome these limitations, INIA has been implementing a genetic improvement program for this species and the generation of interspecific hybrids. The strategy is based on the selection of E. globulus clones with high precocity or foliage turnover, since the adult foliage is more tolerant to T. nubilosa. In addition, controlled crosses of E. globulus and E. maidenii with E. grandis are carried out to incorporate disease resistance and ease of rooting. The multiplication of the selected materials is carried out by micropropagation, but the low rooting capacity is a trait that needs improvement. The cytokines necessary for in vitro proliferation can have a negative effect on the rooting process. Benzyladenine is the most commonly used cytokine because of its low cost and easy availability, with some negative effects on rooting, while meta-topolin is a cytokine of lesser impact. The objective of this study was to evaluate the effect of benzyladenine and meta-topolin on the multiplication rate, rooting percentage and plantlets survival of E. globulus, E. grandis × E. globulus, and E. grandis × E. maidenii. In multiplication media, benzyladenine was supplied at 0.4 µM, while two concentrations of meta-topolin (0.4 and 2 µM) were used. Preliminary results indicated a higher multiplication rate with the inclusion of meta-topolin in both concentrations. The in vitro rooting percentage of explants treated with meta-topolin was 51% and 44%, at 0.4 and 2 µM, respectively, while with benzyladenine was lesser (37%). After 28 days post-transplanting, survival was higher in meta-topolin-derived plants. Meta-topolin improved multiplication, in vitro rooting and acclimation of plants. The use of this hormone could improve micropropagation protocols, facilitating rooting and multiplication of valuable genotypes.

Ergot disease (Claviceps paspali) and sterility have the potential to reduce seed yield in bahiagrass (Paspalum notatum Flüggé). Our objective was to determine the genotypic and environmental effects on seed yield, and the levels of ergot and sterility. Seventeen genotypes were evaluated in three locations across two years for seed yield, ergot severity, and total seed fractions (percentage of full seeds, ergot sclerotia and empty seeds). The percentage of full seeds and total seed yield were correlated (r = 0.52) but both were negatively correlated with the percentage of ergot sclerotia (r = −0.81 and −0.51). Empty seeds were negatively correlated with full seeds (r = −0.39), but not with ergot sclerotia and total seed yield. The genotype effect was significant for total seed yield and severity of infection with large heritabilities (H2 = 0.92 and 0.86) but had no effect on the percentage of the seed fractions. Location and the interaction with genotype explained most of the variation in the percentage of the seed fractions and their weight. Ergot and sterility were significant detrimental factors, genotype was a major determinant of ergot levels and seed yield, while non-genetic factors were co-determinants in constructing the seed yield potential but were the main determinants of the yield potential realization.

Controlling a pest species raises questions about the harmful effects its eradication could cause in ecosystems. Currently, in Uruguay are being analyzed strategies to eradicate the New World Screwworm (NWS), Cochliomyia hominivorax (Diptera: Calliphoridae), an obligatory ectoparasite that causes myiasis in warm-blooded vertebrates, including humans. The loss of a species implies a risk of secondary extinctions and cascading effects that depend on the ecological function of the species and the capacity of the rest of the species with which it interacts to compensate for its loss. To assess the ecological impact of the NWS eradication, we analyzed its ecological redundancy, its effect as an indirect regulatory agent for other species, and its participation in critical ecosystem functions. We conclude that the NWS presents high functional redundancy in most ecological interactions. It does not play an essential role as a regulatory agent of other species and does not play an important role in critical ecosystem functions. Without ignoring the information gaps that certainly exist about the ecological interactions network of the NWS in Uruguay, we estimate that its eradication is unlikely to cause secondary extinctions or cascading effects in the networks it integrates. In order to timely detect possible impacts during the course of the program, it is recommended to monitor the ecosystems using indicators related to direct and indirect partners in the ecological interactions of the NWS.

Bacterial wilt caused by the pathogen Ralstonia solanacearum is a devastating disease of potato crops. Harmonizing immunity to pathogens and crop yield is a balance between productive, economic, and environmental interests. In this work, the agronomic performance of two events of potato cultivar INIA Iporá expressing the Arabidopsis thaliana EFR gene (Iporá EFR 3 and Iporá EFR 12) previously selected for their high resistance to bacterial wilt was evaluated under pathogen-free conditions. During two cultivation cycles, the evaluated phenotypic characteristics were emergence, beginning of flowering, vigor, growth, leaf morphology, yield, number and size of tubers, analyzed under biosecurity standards. The phenotypic characteristics evaluated did not show differences, except in the morphology of the leaf with a more globose appearance and a shortening of the rachis in the transformation events with respect to untransformed Iporá. The Iporá EFR 3 genotype showed a ~40% yield decrease in reference to untransformed Iporá in the two trials, while Iporá EFR 12 did not differ statistically from untransformed Iporá. Iporá EFR 12 shows performance stability in the absence of the pathogen, compared to the untransformed control, positioning it as an interesting candidate for regions where the presence of the pathogen is endemic and bacterial wilt has a high economic impact.

Bacterial wilt caused by the pathogen Ralstonia solanacearum is a devastating disease of potato crops. Harmonizing immunity to pathogens and crop yield is a balance between productive, economic, and environmental interests. In this work, the agronomic performance of two events of potato cultivar INIA Iporá expressing the Arabidopsis thaliana EFR gene (Iporá EFR 3 and Iporá EFR 12) previously selected for their high resistance to bacterial wilt was evaluated under pathogen-free conditions. During two cultivation cycles, the evaluated phenotypic characteristics were emergence, beginning of flowering, vigor, growth, leaf morphology, yield, number and size of tubers, analyzed under biosecurity standards. The phenotypic characteristics evaluated did not show differences, except in the morphology of the leaf with a more globose appearance and a shortening of the rachis in the transformation events with respect to untransformed Iporá. The Iporá EFR 3 genotype showed a ~40% yield decrease in reference to untransformed Iporá in the two trials, while Iporá EFR 12 did not differ statistically from untransformed Iporá. Iporá EFR 12 shows performance stability in the absence of the pathogen, compared to the untransformed control, positioning it as an interesting candidate for regions where the presence of the pathogen is endemic and bacterial wilt has a high economic impact.

Red-banded stink bug Piezodorus guildinii (P. guildinii) has been described as the most damaging stink bug regarding soybean crops, leading to seed injury, low germination percentages, and foliar retention, at low population densities. In recent years, RNA interference (RNAi), a conserved eukaryote silencing mechanism has been explored to develop species-selective pesticides. In this work, we evaluated RNAi in P. guildinii to develop new pest-control strategies. For this, we assembled and annotated a P. guildinii transcriptome from a pool of all developmental stages. Analysis of this transcriptome led to the identification of 56 genes related to the silencing process encompassing siRNA, miRNA, and piRNA pathways. To evaluate the functionality of RNAi machinery, P. guildinii adults were injected with 28 ng/mg of body weight of double stranded RNA (dsRNA) targeting vATPase A. A mortality of 35 and 51.6% was observed after 7 and 14 days, respectively, and a downregulation of vATPase A gene of 84% 72 h post-injection. In addition, Dicer-2 and Argonaute-2 genes, core RNAi proteins, were upregulated 1.8-fold 48 h after injection. These findings showed for the first time that RNAi is functional in P. guildinii and the silencing of essential genes has a significant effect in adult viability. Taken together, the work reported here shows that RNAi could be an interesting approach for the development of red-banded stink bug control strategies.

Additional file S6. Orthofinder results in C. paspali isolates. Orthofinder results based on the PSP of each C. paspali isolate used in this study

A selection of 11 microsatellite markers (SSRs) reported for fingerprinting germplasm collections of Pyrus spp. was used to genotype a collection of cultivars and rootstocks. This set of markers included the "minimum core" established by Evans et al. (2009). Cultivars with known origin ('Williams', 'Abbe Fetel' and 'Doyenne du Comice') were included as reference accessions. The comparison was performed among 44 accessions collected from old pear plantations with different commercial origins and date of introduction to the country. The aim of this study was to genotype pear accessions that were introduced in Uruguay to evaluate the genetic variability among clones and pear rootstocks. The selected markers proved to be effective for variability discrimination in all the accessions having 6 to 12 alleles per locus. The most informative markers were CH01d09, CH02b10 and GD96. Within cultivars, the observed variability among the 13 'Williams' clones could respond to the numerous introductions from different origins that were performed throughout the years of pear production in the country. Although the accessions were grouped in clearly defined clusters as expected before the analysis, they showed variability within cultivars. The accession 00LBPrSJ is a rootstock collected from the locality of San Jose, selected because of its medium to low vigor that leads to medium-sized fruit trees. This accession showed a particular molecular pattern profile characterized by unique alleles that make it genetically distant from other accessions. The above mentioned phenotypic feature represents a very appealing condition, that is suitable for the current cultivation practices overcoming incompatibility problems.

Additional file S2. Functional annotation of C. paspali isolates PSP. Functional annotation and enriched GO terms of PSP, pathogenicity factors and effector-like proteins in C. paspali isolates.

Eucalyptus dunnii Maiden produces good quality cellulose pulp, showing good frost tolerance. However, in Uruguay, it needs more than six years to reach the reproductive stage. Genome duplication was proposed as a strategy to obtain useful variability. The application of mitosis inhibitors for chromosomal duplication, in explants growing in vitro, was evaluated. Two antimitotic agents were used: colchicine and oryzalin in different concentrations and exposure times, in two types of explants: explants growing in vitro and pre-germinated seeds. The number of chloroplasts was used as a rapid ploidy estimator and confirmed by flow cytometry. For chloroplast count, fluorescein diacetate (FDA) applied to in vitro leaves was used for staining. Oryzalin was effective for inducing plant duplication in E. dunnii from in vitro explants. In pre-germinated seeds, both antimitotic agents induced polyploids. The average number of chloroplasts was 5.5 in diploid control plants and more than 7 in tetraploids. Obtained plantlets were successfully cloned in the greenhouse. This is the first report on artificial polyploidy obtained in E. dunnii.

Claviceps species affecting Paspalum spp. are a serious problem, as they infect forage grasses such as Paspalum dilatatum and P. plicatulum, producing the ergot disease. The ascomycete C. paspali is known to be the pathogen responsible for this disease in both grasses. This fungus produces alkaloids, including ergot alkaloids and indole-diterpenes, that have potent neurotropic activities in mammals. A total of 32 isolates from Uruguay were obtained from infected P. dilatatum and P. plicatulum. Isolates were phylogenetically identified using partial sequences of the genes coding for the second largest subunit of RNA polymerase subunit II (RPB2), translation elongation factor 1-α (TEF1), β-tubulin (TUB2), and the nuc rDNA 28S subunit (28S). Isolates were also genotyped by randomly amplified polymorphic DNA (RAPD) and presence of genes within the ergot alkaloid (EAS) and indole-diterpene (IDT) biosynthetic gene clusters. This study represents the first genetic characterization of several isolates of C. paspali. The results from this study provide insight into the genetic and genotypic diversity of Claviceps paspali present in P. dilatatum and suggest that isolates from P. plicatulum could be considered an ecological subspecies or specialized variant of C. paspali. Some of these isolates show hypothetical alkaloid genotypes never reported before.

The objective of this study consisted in a screening of the main hereditary diseases BLAD, DUMPs and Citrullinaemia using the GGP-BovineLDv3 panel in a representative population of Holstein heifers of the eastern area of Uruguay, as well as the analysis of BLAD mutant allele frequency since it was first reported in Uruguay in 2003. DNA was extracted from fresh blood of 190 Holstein heifers in the dairy area of Cerro Largo (Uruguay) and genotyped using the above mentioned panel, thus validating previously used techniques, suhc as PCR- RFLP and PCR- sequencing. We detected the presence of the BLAD mutant allele in one heifer, and allele frequency was estimated as 0.28%. Reported frequencies of BLAD allele during the last 15 years were compared and the reported studies revealed that the frequency progressively decreased and fell to zero in 2018, which can be due to the use of genotyped semen free of these diseases during the last years. No mutant alleles were found for DUMPs or Citrulinaemia. The use of low-density panels would be a useful tool to develop breeding strategies in dairly farms and to monitor hereditary diseases in Holstein breed.