Alessandra Pereira Fávero

Brazilian cattle production relies predominantly on pasture systems, many of which are degraded by nutrient depletion, particularly nitrogen deficiency. Plant growth-promoting bacteria (PGPB) offer a sustainable strategy to improve pasture productivity, but their effects are often host-specific and remain poorly explored in Paspalum. This study evaluated the effect of inoculation with Azospirillum brasilense strains CNPSo 2083 (=Ab-V5) and CNPSo 2084 (=Ab-V6) and Pseudomonas fluorescens strain CNPSo 2719 (=CCTB 03), applied by seed inoculation or leaf spray, on the root morphology and shoot growth of four Paspalum accessions under controlled axenic greenhouse conditions, evaluated in an early growth stage at 35 days after emergence. Genotype-specific responses were the central finding of this study: Paspalum malacophyllum BGP-293 showed negligible responses to inoculation, whereas BGP-486—of the same species—increased root dry weight by up to 43% and root tissue density by up to 30% in all inoculated treatments. In Paspalum regnellii BGP-112, seed inoculation produced stronger root responses than foliar spray, increasing root dry weight by up to 38% and root area by up to 40%. In Paspalum rojasii BGP-149, inoculation induced root architectural remodeling without increasing root biomass—root area increased by up to 92% and total root length by up to 97%, relative to the control—indicating an efficient root-foraging strategy. P. fluorescens favored root-foraging traits and tissue density, whereas A. brasilense preferentially stimulated root-hair elongation. These accession-level contrasts, rather than a single generalizable trend, are the main contribution of this work: they support tailored, genotype-specific PGPB strategies for sustainable tropical pastures.

The decision of various countries to build permanent human bases on the Moon, Mars, or other celestial bodies has sparked growing interest in understanding how plants develop in extraterrestrial environments, particularly because of microgravity and cosmic radiation. This study aimed to describe the state of the art in research on the effects of microgravity and ionizing radiation on plant growth under space conditions. Initially, it highlights the fundamental role of plant cultivation in life support systems, including food production, oxygen recycling for long-duration missions, and more. Subsequently, the review covers studies conducted aboard space platforms such as the International Space Station (ISS), describing how the absence of gravity can alter plant developmental processes. Experimental results demonstrate that microgravity alters cell structure development, hormonal signaling, and nutrient absorption capacity, while space radiation, particularly ionizing radiation, can induce genetic mutations and cause DNA damage in plant cells, affecting plant growth and long-term viability. Reviewing this topic is essential for understanding current knowledge and advancing new research toward the use of plants in efficient and self-sustaining agricultural systems for future interplanetary missions.

Excess soil water can result from inadequate drainage, seasonal groundwater fluctuations, and extreme rainfall events. Diversifying forage species is a key strategy for mitigating these challenges. This study aimed to evaluate Paspalum germplasm collected from different regions of Brazil and identify accessions with potential for use in poorly drained environments. A total of twenty-three Paspalum accessions were assessed under two water regimes (flooded and non-flooded), alongside Urochloa brizantha cv. Marandu, in a randomized block design with a 24 × 2 factorial arrangement and three replications. The experiment was conducted in a greenhouse using potted plants. The evaluated traits were dry mass of leaves, stems, dead material, aerial biomass, roots, the ratio of dead material dry mass to aerial biomass, leaf area, number of tillers, and leaf elongation. Data were subjected to analysis of variance and a means comparison test at a 5% significance level, followed by biplot analysis. All genotypes were affected by flooding; however, BGP238, BGP112, and BGP410 exhibited superior performance in the assessed growth and biomass production traits compared to U. brizantha cv. Marandu under both flooded and non-flooded conditions. These genotypes can advance in plant breeding studies.

Paspalum is a vital forage and turf grass in tropical and subtropical regions, yet its breeding programs face challenges due to the lack of natural flowering synchronization between some parent species. Pollen cryopreservation offers a potential solution to this issue. This study aimed to adapt a cryopreservation protocol for the pollen of P. atratum, P. malacophyllum, and P. regnellii, and to evaluate the viability of cryopreserved pollen grains (CPG) for hybridization purposes. Two dehydrating agents (LiCl and silica gel) were tested for different durations (30, 60, and 120 min) alongside a non-dehydration treatment. The effectiveness of cryopreservation was assessed over multiple time points (1, 10, 30, 90, 180, 270, and 365 days) with freshly harvested grains as controls. Pollen viability was determined using 0.25% 2,3,5-triphenyltetrazolium chloride staining. Viability of CPG ranged from 40.67 to 80.67% across treatments. Optimal dehydration involved LiCl for 30 min and silica gel for 120 min, achieving an average viability of 66% after 12 months, comparable to fresh pollen. In vivo germination tests confirmed successful pollen tube germination with the combinations P. urvillei × P. malacophyllum; P. urvillei × P. regnellii and hybrid (P. plicatulum 4PT × P. guenoarum cv. Azulão) × P. atratum, although pollen tubes did not reach the micropyle in some crosses. This study established effective pollen cryopreservation protocols for P. atratum and P. malacophyllum, facilitating in vivo germination and enhancing the potential for hybridization in Paspalum breeding programs, thereby addressing flowering asynchrony and broadening crossing opportunities within the genus.

The characterization of genetic resources is essential to carry out a breeding program. This study aimed to characterize Paspalum genotypes with potential use as soil surface covering to support breeding programs on the development of turf cultivars. Forty‐three Paspalum genotypes, comprising 11 species, were evaluated. The embryo‐sacs structure was determined by cleared ovaries analysis and eight accessions were classified as sexual, 15 as apomictic, and 20 presenting facultative apomixis. Most of the genotypes have 40 chromosomes, with the exception of one accession of Paspalum vaginatum , two of Paspalum indecorum , one of Paspalum modestum , and two of Paspalum notatum that have 20 and one accession of Paspalum jesuiticum and one of Paspalum mandiocanum that have 60 chromosomes. DNA content was determined by flow cytometry, ranging from 1.35 to 4.00 pg of DNA, with most of the accessions corresponding to tetraploidy, but also diploidy and hexaploidy were found, corroborating chromosome counts. High genetic variability was found among the 43 accessions based on 11 microsatellite markers and their use to estimate Jaccard similarity coefficients and Bayesian analysis, forming six different genetic groups. Considering only the P. notatum accessions, great variability was observed with four distinct groups formed. The results presented in this work reveal the possibility to obtain assertive crosses between compatible parents, aiming to explore the genetic variability between and within species of this genus.

Plant growth–promoting bacteria (PGPB) can play an essential role as biofertilizers to increase pasture efficiency and reduce the application of agrochemicals. Plant growth can be potentialized when these bacteria are combined with silica nanoparticles (SiNPs). The present study aimed to evaluate the effect of PGPB associated with SiNPs on the growth of bahiagrass (Paspalum notatum) seedlings. The PGPB were isolated from rhizospheric soils and leaves of Paspalum spp. grown in the tropical high‐altitude region of Brazil and selected by their ability to fix nitrogen, solubilize phosphate, and synthesize indoleacetic acid (IAA). They were identified as Alcaligenes faecalis, Enterobacter asburiae, and Serratia marcescens by 16S rDNA sequencing. Spherical SiNPs (85 nm in diameter) were synthesized by the hydrolysis of the silicon precursor tetraethyl orthosilicate (TEOS), characterized by infrared spectroscopy and scanning electron microscopy (SEM) and applied at 5% (0.05 mg·mL⁻¹) and 10% (0.1 mg·mL⁻¹) concentrations. Disinfected P. notatum seeds were treated with PGPB, SiNPs, and PGPB + SiNPs and cultivated in magenta boxes containing peat, sand, and perlite. The seedlings were evaluated for their germination percentage, root length, shoot length, root dry weight, and shoot dry weight. Disinfected seeds subjected to the same treatments were also grown in Petri dishes containing 0.7% agarose. The roots of the seedlings in Petri dishes were stained with diaminobenzidine tetrahydrochloride (DAB) and visualized using a light microscope to confirm bacterial colonization. The three strains without SiNPs promoted the growth of P. notatum seedlings. S. marcescens treatment presented the greatest shoot length, and both concentrations of nanosilica with PGPB improved or maintained root lengths. Treatments of S. marcescens and E. asburiae with 10% SiNPs showed 100% seed germination. Seedlings inoculated with 10% SiNPs with S. marcescens and E. asburiae alone showed the highest shoot dry weight, and all treatments increased root dry weight compared to the control. The 10% SiNPs’ concentration inoculated with S. marcescens and A. faecalis positively affected P. notatum seedlings’ growth. This study suggests that nanosilica can be applied with PGPB to improve the development of bahiagrass and reduce the need for applications of agrochemicals.

This study investigated the agronomic, nutritive value, cytogenetic, molecular, and reproductive aspects of twenty‐five Paspalum accessions to support breeding programs. The agronomic aspects and the nutritive value were evaluated in a randomized block experimental design with four replications, and with monthly repeated measures for 2 years. For the molecular characterization 16 microsatellite markers developed for different Paspalum species in previous works were used. The number of chromosomes was determined by visualizing the meiotic cells and the DNA content was determined by flow cytometry. The embryo sac clarification technique was used to characterize the reproductive system. The results indicated genetic variability for all the variables related to yield and nutritive value. For almost all variables, the values of Paspalum accessions were higher than those of the commercial cultivars Megathyrsus maximus cv. Tanzania and Urochloa brizantha cv. Marandu, used as references. However, the accessions showed in vitro dry matter digestibility values lower than the mean value presented by the references. The groups formed in the molecular analysis showed correspondence to the groups observed in the principal components analysis, considering the variables related to yield and nutritive value. Most accessions were revealed to be tetraploid with 40 chromosomes and most accessions belonging to the Virgata group displayed a sexual embryo sac structure. Some crosses can be indicated for genetic breeding, due to a superior genomic affinity between the accessions and the higher probability of heterosis in the progeny. These results provide subsidies to genetic plant breeding programs that use these accessions.

Background: Paspalum notatum exhibits both sexual and apomictic cytotypes and, thus, is considered a good model for studies of apomixis because it facilitates comparative approaches. In this work, transcriptome sequencing was used to compare contrasting P. notatum cytotypes to identify differential expression patterns and candidate genes involved in the regulation of expression of this trait. Results: We built a comprehensive transcriptome using leaf and inflorescence from apomictic tetraploids and sexual diploids/tetraploids and a coexpression network based on pairwise correlations between transcript expression profiles. We identified genes exclusively expressed in each cytotype and genes differentially expressed between pairs of cytotypes. Gene Ontology enrichment analyses were performed to better interpret the data. We de novo assembled 114,306 reference transcripts. In total, 536 candidate genes possibly associated with apomixis were detected through statistical analyses of the differential expression data, and several interacting genes potentially linked to the apomixis-controlling region, genes that have already been reported in the literature, and their neighbors were transcriptionally related in the coexpression network. Conclusions: Apomixis is a highly desirable trait in modern agriculture due to the maintenance of the characteristics of the mother plant in the progeny. The reference transcriptome, candidate genes and their coexpression network identified in this work represent rich resources for future grass breeding programs.