Panicle Research Articles

Panicum maximum cultivars for use in integrated agricultural production systems in Cerrado biome soils

AbstractIntegrated production systems have been an alternative for diversifying agricultural production, and therefore, it is necessary to study tropical forage grasses that can impact both straw production and soil organic matter, as well as benefit animal production. The objective of this work was to evaluate the productive characteristics and accumulation of nutrients in the biomass of grasses of the genus Panicum grown in the off‐season, in Cerrado biome soil as cover plants for use in integrated production systems. It evaluated different grasses of Panicum maximum: Aruana, Tamani, and Massai guinea grasses, distributed in a randomized block design with four replications of each grass. The productive characteristics, mineral accumulation, and carbon/nitrogen (C/N) ratio in the biomass of the cultivars were evaluated. No cultivar effect was observed for forage mass (3997.4 kg/ha DM). However, the largest (p = 0.0077) leaf blade masses were observed in the Massai and Tamani guinea grasses. On the contrary, the Aruana guinea grass exhibited the highest value (p = 0.0001) for stem mass, reflected in a higher (p = 0.0001) leaf/stalk ratio in the Massai and Tamani guinea grasses. No effect (p > 0.05) of the cultivar on micronutrients, magnesium, and phosphorus concentrations was observed. However, the Aruana guinea grass presented higher concentrations of calcium and sulfur; on the other hand, potassium values were higher in the Massai and Tamani guinea grasses. The Massai guinea grass exhibited a higher (p = 0.0214) C/N ratio, while the Aruana guinea grass recorded lower values, with no significant differences between these cultivars and Tamani guinea grass. The Tamani and Massai guinea grasses stand out as recommended choices for cultivation during the off‐season in Cerrado biome soils as cover crops in integrated production systems.

Seedling emergence of tropical perennial pasture species in response to temperature used to determine sowing time recommendations

Tropical pasture grasses and legumes can be highly productive and persistent and fill the summer-autumn feed gap typical of temperate pasture systems in southern Australia. However, more information is needed on optimum temperature range for seedling emergence because this will influence sowing time recommendations. A replicated field experiment was conducted at 5 locations in New South Wales over a 12-month period to determine the optimum temperature for emergence of a range of tropical species: Rhodes grass (Chloris gayana Kunth), Makarikari grass (Panicum coloratum L. var. makarikariense Gooss.), kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone), digit grass (Digitaria eriantha Steud.), panic grass (Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs), paspalum (Paspalum dilatatum Poir.), Urochloa hybrid (Urochloa decumbens × U. ruziziensis × U. brizantha), 2 cultivars of Desmanthus virgatus (L.) Willd. (cultivars ‘Marc’ and ‘JCU2’), D. bicornutus (S. Watson), D. leptophyllus (Kunth) and D. pernambucanus (L.) Thell.). Rhodes grass emerged satisfactorily over the longest time across all sites, exhibiting the greatest temperature range over which emergence occurred, while Makarikari grass and panic grass had the narrowest temperature range for emergence. The temperature for 50% emergence differed between the tropical species and whether the soils were warming or cooling. Rhodes grass had the lowest 50% emergence temperature (17 °C) while paspalum had the highest (22 °C). Results showed that temperature for 50% emergence is a useful indicator for determining sowing time in warming soils.

A Pilot Study to Identify Grass Species That Mediate Pollen Allergy in Thailand

Introduction: Some grass species that are either common or widely spread in Thailand have not been used for pollen allergy diagnosis. In order to improve diagnostic accuracy, the aim of this pilot study was to identify the grass species responsible for pollen allergy in Thailand. Methods: The skin sensitization of pollen extracts from six different grass species, including rice (Oryza sativa), corn (Zea mays), sorghum (Sorghum bicolor), para grass (Urochloa mutica), ruzi grass (Urochloa eminii), and green panic grass (Megathyrsus maximus), was evaluated by skin prick test (SPT). Serum’s IgE specific to each pollen extract was analyzed by Western blot (WB). The ImmunoCAPTM test for Johnson grass was also evaluated. Results: Of the thirty-six volunteers who participated in this study, eighteen tested positive for at least one of the diagnostic tests, namely SPT, WB analysis, or ImmunoCAPTM. Notably, skin reactivity to para grass, corn, sorghum, and rice was more commonly observed compared to ruzi grass and green panic grass. However, in the WB analysis, individuals with pollen-specific IgE were more frequently detected in sorghum, green panic grass, corn, rice, and ruzi grass than para grass. Conclusion: In this pilot investigation, our findings indicate that the pollen extracts of rice, corn, sorghum, and para grass are associated with pollen allergy in Thailand. These results contribute to the current knowledge on the identification of grass species that are associated with pollen allergy in Thailand and Southeast Asia.

Responses of Panicum and Brachiaria to irrigation during winter in the Goiás’ Cerrado-Brazil

Forage production in the Cerrado is based on well-defined seasons: a rainy summer, and a dry winter. To define strategies that minimize the seasonality of forage production, responses in growth and biomass accumulation of five irrigated forages were evaluated during winter. The experimental design was randomized blocks, in a split plot arrangement, with five replicates, five forages in the plots (three of Panicum maximum - Mombasa, Tanzania, and Masai; two of Brachiaria brizantha - piatã and MG5), and five cuts in the subplots made from July to October 2016. Forages were cultivated with centre-pivot irrigation and the water level was defined according to the reference evapotranspiration determined through a Class A pan evaporation method, 0.8 kc, and two-day irrigation shifts. The number of shoots, leaves/tiller, leaves/plant, fresh leaf and stem biomass, dry leaf and stem biomass, fresh leaf mass/fresh stem mass ratio, dry leaf mass/dry stem mass ratio, and biomass accumulated in the five cuts were calculated. Irrigated forage during winter in the Goiás’ Cerrado showed satisfactory growth, reaching a lower plant height between cuts than those reported in the literature. Among the Panicum grasses, Mombasa grass stood out, and MG was superior to piatã grass. Highlights The forages Panicum maximum - Mombasa, Tanzania, and Masai -; and Brachiaria brizantha - piatã and MG5 -, presented satisfactory responses in growth and biomass accumulation in an irrigated culture during winter in the Goiás’ Cerrado. The Mombasa grass stood out among the forage of the genus Panicum and MG5 in the Brachiaria. The Mombasa and Brachiaria MG5 grasses are recommended for cultivation of irrigated forage during the winter in the Goiás’ Cerrado.

Two Coastal Plain Dichanthelium (Poaceae: Paniceae) Disjunct in Tennessee Grasslands and Their Conservation

Dichanthelium wrightianum, a species of panic grass whose North American range is exclusive to the Coastal Plain, is reported from Tennessee for the first time. A single population of this species was discovered in a wet grassland remnant in the Eastern Highland Rim physiographic region alongside many other species disjunct from the Coastal Plain. Another Coastal Plain Dichanthelium, D. roanokense, was found at a second wet grassland nearby. While D. roanokense was previously reported for Tennessee, it has not been recently documented or confirmed to be extant within the state and its current status should be reviewed. The ecology and conservation of Tennessee populations of both species are discussed.

Seed yield potential improvement through breeding in

Context Panicum coloratum is a relatively undomesticated small-seeded warm-season forage grass. Seed shattering, an extended reproductive period and non-synchronic seed maturation limit harvested seed yields. Low seed quantity and quality hinder pasture establishment and discourage its use. Aims To assess whether seed yield potential could be improved by breeding, we sought to measure variability in traits related to seed production including phenotypic plasticity in response to environmental cues, and estimated narrow-sense heritability, prospective genetic gain after selection and co-heritabilities in seed yield components. Methods Seed retention (SR), number of panicles (PN), seed number per panicle (SN) and seed weight (SW) were measured in plants growing in the field. Clonal replicates of 13 genotypes were assessed in 2007 and 2010 and half-sib families derived from these genotypes were measured in 2010. Key results Phenotypic variability among genotypes was related to genetic factors for all measured variables. Two broad groups of accessions showing differences in SR were studied. Phenotypic plasticity in SR differed among genotypes and was negatively related to levels of SR, implying that stable high-SR genotypes could be selected in a breeding program. Maximum narrow-sense heritabilities were 0.89 and 0.41 for SN and SR, respectively, with estimated gains after selection around 30%. The best results were achieved if selecting for SR at 3–5 weeks after anthesis. Low genetic correlations and extremely low co-heritabilities between other characters and seed yield components discourage the possibility of indirect selection. Conclusion Moderate increases in seed production potential may be achieved after selection for SN, SW and SR in P. coloratum var. makarikariense. Implications Improvements in SR and other seed yield components would facilitate harvest, increase yield and consequently increase profitability to growers and stimulate pasture adoption by farmers.

Non-thermal plasma application improves germination, establishment and productivity of Gatton panic grass (

Megathyrsus maximus (Gatton panic) is a tropical grass highly valued both for its use as forage and for its biofuel potential. A major constraint in establishing pastures of this cultivar is the low viability and germination of seeds and the poor initial seedling establishment. We used non-thermal plasma (NTP, partially ionised gas) as a novel technology to treat seeds of this grass, aiming to improve their quality (i.e. germination traits). We also followed the performance of seedlings grown from NTP-treated seeds under field conditions by assessing seedling establishment, biomass production and forage quality during the first regrowth period, which is the critical period for pasture establishment. Two NTP treatments were performed through dielectric barrier discharges employing N2 as carrier gas. Non-treated seeds served as the control. Results showed that the viability of NTP-treated seeds was, on average, 1.5-fold higher than the control, and that germination energy and germination percentage of treated seeds was superior to the control by 2.1-fold and 2.2-fold, respectively. A field experiment showed that seedling establishment parameters (dynamics of cumulative emergence, emergence coefficient, and weighted average emergence rate) and pasture early productivity (represented by shoot dry matter) were enhanced by NTP treatment (phenolic sheet–polyester film barrier and 3 min exposure), showing 1.4–2.6-fold higher values than the control, confirming the results of the laboratory assays. Although NTP markedly increased the shoot dry matter production of the pasture, which was related to higher tiller population density and greater tiller weight, it did not affect the forage quality of the plants grown in the field. We conclude that NTP technology is suitable to improve seed germination of Gatton panic, in turn leading to improvements in seedling establishment and biomass production under field conditions without compromising forage quality.

Genotypic identification of Panicum spp. in New South Wales, Australia using DNA barcoding

Australia has over 30 Panicum spp. (panic grass) including several non-native species that cause crop and pasture loss and hepatogenous photosensitisation in livestock. It is critical to correctly identify them at the species level to facilitate the development of appropriate management strategies for efficacious control of Panicum grasses in crops, fallows and pastures. Currently, identification of Panicum spp. relies on morphological examination of the reproductive structures, but this approach is only useful for flowering specimens and requires significant taxonomic expertise. To overcome this limitation, we used multi-locus DNA barcoding for the identification of ten selected Panicum spp. found in Australia. With the exception of P. buncei, other native Australian Panicum were genetically separated at the species level and distinguished from non-native species. One nuclear (ITS) and two chloroplast regions (matK and trnL intron-trnF) were identified with varying facility for DNA barcode separation of the Panicum species. Concatenation of sequences from ITS, matK and trnL intron-trnF regions provided clear separation of eight regionally collected species, with a maximum intraspecific distance of 0.22% and minimum interspecific distance of 0.33%. Two of three non-native Panicum species exhibited a smaller genome size compared to native species evaluated, and we speculate that this may be associated with biological advantages impacting invasion of non-native Panicum species in novel locations. We conclude that multi-locus DNA barcoding, in combination with traditional taxonomic identification, provides an accurate and cost-effective adjunctive tool for further distinguishing Panicum spp. at the species level.

A new combination in the genus Louisiella (Poaceae: Paniceae)

The critical study of Panicum paludosum implied that its taxonomic position within the genus Panicum is apparently discordant for its linear hilum, spongy culms, linear spikelets, barren lower floret, and upper floret smooth. These attributes best conform the circumscription of the ditypic genus Louisiella. Thus, it has been transferred into the same and a key to distinguish all the congeners in the world is provided. The close affinities and differences of this species with a close one, Panicum repense are also briefly discussed. The illustration of the spikelet and the caryopsis are included to support its new placement in Louisiella. A detailed comparison in all the three species of Louisiella is given to facilitate the proper identification.

Cattle performance with Brachiaria and Panicum maximum forages in an integrated crop-livestock system

Crop-livestock integration is an efficient technique that enables cropping and animal production in the same area, takes advantage of all the benefits that this synergism provides, and results in greater sustainability and lower environmental impact. The objectives of this study were to evaluate the production, forage quality, and cattle performance with forages of the genus Brachiaria and Panicum maximum after intercropping with soybean in an integrated crop-livestock system and to assess the relationship between mulch biomass and soybean yield. The experimental design was completely randomised and consisted of a 4 × 5 factorial arrangement with four replicates. The treatments consisted of four forages, namely, Xaraes palisadegrass (Brachiaria brizantha cv. Xaraés), Congo grass (Brachiaria ruziziensis), Mombaça guinea grass (Panicum maximum cv. Mombaça), and Tamani guinea grass (Panicum maximum cv. BRS Tamani), intercropped with oversown soybean, and these treatments were evaluated over five grazing cycles. The results showed that Mombaça guinea grass and Xaraes palisadegrass were associated with higher forage production, but the highest forage quality was obtained with Tamani guinea grass. Mombaça guinea grass, Xaraes palisadegrass, and Tamani guinea grass resulted in the best pasture performance of animals under grazing in the off-season and thus generated more benefits in terms of the soybean yield. Congo grass was associated with reduced production, lower forage quality and decreased animal production during the grazing cycles. The pasture establishment through soybean over sowing proved to be an efficient technique that reduced the environmental impact of livestock, because of the greater use of soil nutrients and resulted in greater sustainability.

Nueva variedad de “quinua” Chenopodium quinoa Wild. (Chenopodiaceae) para la sierra norte del Perú con características agronómicas y comerciales sobresalientes

In order to generate a new variety of quinoa for the northern highlands of Peru and contribute to the competitiveness of this andean grain, this research was carried out between 2013 and 2018. Phases of introduction and evaluation of germplasm, genetic improvement and advanced evaluation of promising materials were carried out. The first two phases carried out in INIA experimental fields and the third in farmer’s fields. Phenotypic characteristics, physiological maturity, mildew reaction and grain yield were evaluated. Also, there was opinion of farmers. Quantitative data was analyzed using ANVA and Duncan’s test. From the Genetic Compound A, introduced from the central highlands, the new variety of quinoa was generated, called INIA 437 Red of the North. It is accepted by the farmers of the research, It has white grain and semi-sweetness; purple in foliage and panicle; as well as outstanding characteristics of mildew tolerance and productivity, showing less damage to the disease and greater yield than the Witness, White of Junin variety; also It has greater profitability and productive stability than this; being suitable for cultivation in the study area.

Growth response of blue panic grass (Panicum antidotale) to saline water irrigation and compost applications

ABSTRACT A pot experiment was conducted to examine the ability of Blue Panic grass (Panicum antidotale) to grow in slightly saline soils (2.40 dS m–1) under different levels of saline irrigation water in the presence or absence of compost. Eight treatments were set up in a randomized block design with five replicates as follows: T1 (Freshwater), T2 (Freshwater + compost at 20%), T3 (Saline water 5000 mg L–1), T4 (T3 + compost at 20%), T5 (Saline water 10000 mg L–1), T6 (T5 + compost at 20%), T7 (Saline water 15000 mg L–1) and T8 (T7 + compost at 20%). Growth parameters of Blue Panic Grass were evaluated at the end of the experimental period as plant and root length, shoot, and root fresh and dry weights, total chlorophyll, and total carbohydrates. In general, tested Blue Panic Grass appeared to be tolerant to high salt concentrations in irrigation water, and slightly significant differences were found for all the measured parameters. A remarkable growth increase occurred in plants grown in compost-amended soils, with respect to the unamended soils. The results demonstrate the possibility to stabilize the yield of blue panic grass, an important feed crop in Egypt, irrigated with saline water, which can secure animal feed resources without reducing the already limited freshwater availability.

Contenido de materia orgánica en suelos de sistemas silvopastoriles establecidos en el Chaco Central paraguayo

El sistema silvopastoril se caracteriza por asociación de ganadería, árboles y pastura, la interacción entre estos componentes aporta beneficios tanto al suelo, como a la pastura, al ganado y a los árboles y permite un aumento en la productividad y la diversificación de la producción. Para conocer la influencia del componente arbóreo del sistema silvopastoril sobre el contenido de materia orgánica del suelo se llevó a cabo un estudio exploratorio en propiedades privadas ubicadas en los Departamento de Boquerón y Presidente Hayes del Chaco Central paraguayo. Se instalaron 8 parcelas permanentes de 1 ha cada una en las que se midieron y registraron todos los individuos de algarrobo (Prosopis spp), se identificaron y extrajeron muestras de pastura de subparcelas de 1m2 que se ubicaron bajo la copa de los árboles y fuera de la copa para comparar la biomasa de la pastura, se extrajeron muestras de suelo bajo las condiciones mencionadas y a dos profundidades, de 0 a 10 cm y de 10 a 30 cm, para comparar el contenido de materia orgánica, carbono y nitrógeno. El componente arbóreo estaba integrado por algarrobo blanco (Prosopis alba) y algarrobo negro (Prosopis nigra) asociados a pastura implantada, Gatton panic (Panicum máximum cv Gatton panic) pasto Pangola (Digitaria decumbens) y pasto Buffel (Cenchrus ciliaris) mayoritariamente. No se registraron diferencias significativas en el contenido de materia orgánica, carbono y nitrógeno entre condiciones de sol y de sombra, pero sí al variar la profundidad. Bajo las condiciones del presente estudio no se registró una influencia significativa del componente arbóreo sobre el contenido de materia orgánica.

Identification, evolutionary and expression analysis of the galactinol synthase (GolS) genes in Panicum virgatum L. and Panicum hallii : An in silico approach

Galactinol synthase (GS; EC 2.4.1.123) is an important enzyme which catalyzes the first step in the raffinose family oligosaccharides (RFOs) biosynthetic pathway. Galactinol synthase genes (GolS) are encoded by multiple genes in the genomes of monocots and dicots and these allelic variants participate in many biological processes. This study presents the first genome-wide analysis of GolS genes in two switchgrass species. We identified a total of six GolS genes/proteins in Panicum virgatum L. and P. hallii genome. Furthermore, we analyzed in silico all PhGolS and PvGolS genes in terms of protein length, molecular weight, theoretical isoelectric point, and 3D protein structure. The subcellular location was mainly predicted as cytoplasmic. Genomic organization revealed that most PhGolS and PvGolS genes have two or three exons. Subsequently, the conserved motifs were identified; they demonstrated high group-specificity in all PhGolS and PvGolS proteins. Comparative phylogenetic analysis of the PhGolS and PvGolS proteins revealed two distinct groups. Synteny events comparisons of the GolS genes in genus Panicum with those of Arabidopsis thaliana, Oryza sativa, Zea mays, and Brachypodium distachyon led to the identification of several orthologous genes, which provided that the GolS genes in plants happened to feature distinct origins, and the synteny of them are conserved among monocots. Transcriptional profiles revealed that GolS genes were expressed in different tissues, indicating that these genes may be involved in various physiological functions. Collectively, the results obtained from this study provide valuable information for further functional characterization of the GolS genes in these important switchgrass species.

Enhancing growth and yield potential of foxtail millet through potassium application in eastern dry zone of Karnataka

As we know that intensive cropping with high yielding varieties makes considerable demand on the soil nutrients and application of nitrogen alone is not a prescription to obtain higher yields without other nutrients supplement. The red soils of Southern Karnataka are natively rich in potassium, hence potassium is not recommended for foxtail millet in Eastern Dry Zone of Karnataka. However, long-term intensive cropping without its application resulted in low to medium status and reduced potassium supply to crop plants and consequently crop yields. By considering nutritional aspects, different levels of potassium have been applied to foxtail millet. Totally twelve treatments were tested which includes absolute control, recommended dose of fertilizers as per UAS, Bangalore package (40:40:0 kg N, P2O5 and K2O per hectare, same level of nitrogen, phosphorus and 10, 20, 30, 40 and 50 kg of potassium, 50 kg nitrogen, 45 kg phosphorus, 10, 20, 30, 40 and 50 kg of potassium. These treatments were replicated thrice using RCBD. The initial soil was low in potassium (119.84 kg ha-1), neutral in reaction (6.59), low organic carbon (0.47%), low available nitrogen (136.42 kg ha-1), phosphorus (16.62 kg ha-1) and sandy loam in texture. From the experiment it was clear that, application of 40 kg nitrogen, 40 kg phosphorus and 40 kg potassium along with 7 tonnes of FYM is performed well by recording highest plant height, number of tillers, panicle length, panicle weight, grain yield and straw yield. Application of increased levels of potassium significantly increased the yield potential of the foxtail millet.

Óleo vegetal na dieta de equinos submetidos a exercício

Objetivou-se e avaliar os efeitos da adição de óleo de soja nos parâmetros séricos e fisiológicos de equinos submetidos a exercício físico. Foram utilizadas 6 éguas da raça Crioula, com idade de quatro anos, e peso aproximado de 350 kg. Os tratamentos foram: Controle 5 kg de MS de aveia (Avena sativa) e 5 kg de MS de Capim Aruana (Panicum Jacq., cv. Aruana); Tratado: 3,52 kg de aveia (Avena sativa), 5 kg de MS de Capim Aruana (Panicum Jacq., cv. Aruana) e 500 g de óleo de soja. Foram efetuadas pesagens e coleta de sangue, no dia 0, 14 e 28 dias de experimento em jejum para análise dos parâmetros séricos. Aos 28 dias de experimentação os equinos foram submetidos a exercício, durante 30 minutos. Antes do início foram realizadas coletas, em jejum, pela manhã e imediatamente após o exercício, 10 minutos e 3 horas após o fim do exercício, além de aferir os parâmetros fisiológicos antes e logo após o exercício. Os valores apresentaram diferença significativa (P<0,05) para colesterol total, HDL, LDL, VLDL e triglicerídeo aos 14 dias de experimento, aos 28 dias diferença apenas para (P<0,05) colesterol total e LDL. Com a realização do exercício não houve diferença nos parâmetros séricos, mas observou-se diferença para os parâmetros fisiológicos entre os períodos de coleta. A adição de óleo de soja na dieta de equinos submetidos a exercício não interfere os parâmetros séricos, tornando-se assim uma alternativa para dietas energéticas.

Pastagens cultivadas como modificadoras dos padrões ecológicos dos organismos edáficos

A macrofauna edáfica engloba diversos organismos que desempenham importante papel na ciclagem de nutrientes e melhorias na propriedade química e física do solo. Estes organismos são utilizados como bioindicadores do funcionamento dos ecossistemas. Visando tais fatores, objetivou-se avaliar a diversidade populacional dos organismos edáficos em áreas com diferentes pastagens cultivadas. O experimento foi conduzido na zona da mata alagoana, no município de Coruripe, Alagoas. O estudo foi realizado em quatro pastagens com cultivo de Mombaça (Panicum maximum), Tifton 85 (Cynodon spp.), Brachiaria humidicola e Brachiaria Brizantha com uma área de 100m² cada. Foram utilizadas 20 armadilhas do tipo Provid por pastagem. Após 96 horas de instalação das armadilhas, os organismos foram quantificados, identificados e agrupados conforme a ordem e/ou grupo taxonômico. Após as análises dos dados observou-se que a área ocupada com capim B. Brizantha teve a maior diversidade, sendo seguida pelas áreas com Mombaça e tifton 85. A área com menor diversidade foi a ocupada com a pastagem B. humidicola. A ordem Aranae esteve presente em todas as áreas, com representação acima de 3,85 dos indivíduos encontrados. Todas as pastagens apresentaram maior representatividade da ordem Hymenoptera. Os Coleopteras apresentaram população mais densa (2,60) e dominante (0,23) na pastagem de mombaça. A fauna edáfica é sujeita a alteração conforme a alteração da vegetação utilizada para a formação da pastagem.

Comparative transcriptomics reveal insights into the drought response of the three Panicum species P. bisulcatum, P. laetum and P. turgidum

Droughts have a major impact on plant growth, limit global net primary production and are predicted to increase in the course of climate change. Knowledge of the plant drought response on a molecular level can facilitate the selection of drought resistant genotypes and genetic engineering and thereby support strategies to preserve natural and agricultural vegetation against drought stress. Since species from the genus Panicum are naturally adapted to varying degrees of drought, they are perfectly suited for comparative studies of the plant drought response.To shed light on the molecular mechanisms of the drought stress response in the genus Panicum, three species that differ in their drought tolerance, P. bisulcatum, P. laetum and P. turgidum were exposed to severe drought stress and subsequent recovery. An RNA-Seq was conducted and de novo transcript assemblies were generated. Differential gene expression analyses revealed 108 genes that are upregulated upon drought stress in all three species, as well as 179 genes that were found consistently downregulated.35 commonly upregulated and 69 commonly downregulated genes were assigned to a regulatory role in the drought response, while 43 commonly upregulated and 77 commonly downregulated genes were assigned to a functional role. The assigned functions and pathways comprise, among others, abscisic acid (ABA) synthesis, signal transduction, osmolyte synthesis, protection of macromolecules, cell wall and cuticle remodeling and drought-induced dormancy. Some of the functionally annotated orthologs have not been reported to be drought responsive yet, among them an oil body associated gene (OBAP2B), a chaperone from endoplasmic reticulum (BCAP31-like) and 30 commonly upregulated and 33 commonly downregulated orthologs with unknown function. Additionally, 150 genes were identified, that were found to be upregulated in the more drought tolerant P. laetum and P. turgidum but not in the more drought sensitive P. bisulcatum and therefore might contribute to their higher drought tolerance.

New Soil, Old Plants, and Ubiquitous Microbes: Evaluating the Potential of Incipient Basaltic Soil to Support Native Plant Growth and Influence Belowground Soil Microbial Community Composition

The plant–microbe–soil nexus is critical in maintaining biogeochemical balance of the biosphere. However, soil loss and land degradation are occurring at alarmingly high rates, with soil loss exceeding soil formation rates. This necessitates evaluating marginal soils for their capacity to support and sustain plant growth. In a greenhouse study, we evaluated the capacity of marginal incipient basaltic parent material to support native plant growth and the associated variation in soil microbial community dynamics. Three plant species, native to the Southwestern Arizona-Sonora region, were tested with three soil treatments, including basaltic parent material, parent material amended with 20% compost, and potting soil. The parent material with and without compost supported 15%, 40%, and 70% germination of Common Bean (Phaseolus vulgaris L. ‘Tarahumara Norteño’), Mesquite (Prosopis pubescens Benth), and Panic Grass (Panicum Sonorum Beal), respectively, though germination was lower than in the potting soil. Plant growth was also sustained over the 30 day period, with plants in parent material (with and without amendment) reaching 50% height compared to those in the potting soil. A 16S rRNA gene amplicon sequencing approach showed Proteobacteria to be the most abundant phyla in both parent material and potting soil, followed by Actinobacteria. The potting soil showed Gammaproteobacteria (19.6%) to be the second most abundant class, but its abundance was reduced in the soil + plants treatment (5.6%–9.6%). Within the basalt soil type, Alphaproteobacteria (42.7%) and Actinobacteria (16.3%) had a higher abundance in the evaluated bean plant species. Microbial community composition had strong correlations with soil characteristics, but not plant attributes within a given soil material. Predictive functional potential capacity of the communities revealed chemoheterotrophy as the most abundant metabolism within the parent material, while photoheterotrophy and anoxygenic photoautotrophy were prevalent in the potting soil. These results show that marginal incipient basaltic soil, both with and without compost amendments, can support native plant species growth, and non-linear associations may exist between plant–marginal soil–microbial interactions.

Producción de metano y bióxido de carbono in vitro de pastos tropicales de la costa de Oaxaca, México

Los pastos tropicales poseen baja concentración de proteína cruda y mayor fibra detergente neutra. Los pastos fermentados en el rumen, presentan diferentes valores de digestibilidad, concentración de ácidos grasos volátiles (AGV), producción de metano (CH4) y bióxido de carbono (CO2). Objetivo: determinar la composición química, caracterizar la fermentación y estimar la producción de CH4 y CO2 in vitro en pastos tropicales de Oaxaca. Materiales y métodos. Los pastos (0.5 g de materia seca): Cynodon nlemfuensis, Andropogon gayanus, Penissetum purpureum cv. Taiwán Morado, Penissetum purpureum cv. Maralfalfa y Panicum maximum, fueron incubados con 45 mL de medio para microorganismos anaerobios, y depositados en viales de vidrio de 100 mL mantenidos en condiciones anaerobias con CO2. Los pastos fueron inoculados con cinco mL de fluido ruminal de bovino e incubados a 39 °C durante 72 h. A las 6, 12, 24, 48 72 h se determinó la producción de biogás y la población de microorganismos. La concentración de AGV, pH y degradación de la materia seca in vitro (DIVMS) se determinaron a 72 h. A 24, 48 y 72 h se midió la producción de CH4 y CO2. Las variables se evaluaron mediante un diseño completamente aleatorizado utilizando cinco repeticiones por tratamiento, la comparación de medias se realizó mediante la prueba de Tukey. Cynodon nlemfuensis tuvo el mayor contenido de proteína cruda (P = 0.05). Las poblaciones de bacterias celulolíticas presentaron menor conteo en Andropogon gayanus así como en Panicum máximum (P < 0.05). Cynodon nlemfuensis, Andropogon gayanus y Pennisetum purpureum cv. Taiwán Morado presentaron menores concentraciones de acetato (P < 0.05), Pannicum maximum tuvo mayor concentración de propionato (P < 0.05). Pennisetum purpureum cv. Maralfalfa presentó la mayor DIVMS y produjo menor volumen de CH4 (P < 0.05), Cynodon nlemfuensis y Pannicum maximum produjeron menores volúmenes de CO2 (P < 0.05).