Physiological responses and transcriptomic changes reveal the mechanisms underlying adaptation of Stylosanthes guianensis to phosphorus deficiency

Background Phosphorus (P) is an essential macronutrient for plant growth that participates in a series of biological processes. Thus, P deficiency limits crop growth and yield. Although Stylosanthes guianensis (stylo) is an important tropical legume that displays adaptation to low phosphate (Pi) availability, its adaptive mechanisms remain largely unknown. Results In this study, differences in low-P stress tolerance were investigated using two stylo cultivars (‘RY2’ and ‘RY5’) that were grown in hydroponics. Results showed that cultivar RY2 was better adapted to Pi starvation than RY5, as reflected by lower values of relative decrease rates of growth parameters than RY5 at low-P stress, especially for the reduction of shoot and root dry weight. Furthermore, RY2 exhibited higher P acquisition efficiency than RY5 under the same P treatment, although P utilization efficiency was similar between the two cultivars. In addition, better root growth performance and higher leaf and root APase activities were observed with RY2 compared to RY5. Subsequent RNA-seq analysis revealed 8,348 genes that were differentially expressed under P deficient and sufficient conditions in RY2 roots, with many Pi starvation regulated genes associated with P metabolic process, protein modification process, transport and other metabolic processes. A group of differentially expressed genes (DEGs) involved in Pi uptake and Pi homeostasis were identified, such as genes encoding Pi transporter (PT), purple acid phosphatase (PAP), and multidrug and toxin extrusion (MATE). Furthermore, a variety of genes related to transcription factors and regulators involved in Pi signaling, including genes belonging to the PHOSPHATE STARVATION RESPONSE 1-like (PHR1), WRKY and the SYG1/PHO81/XPR1 (SPX) domain, were also regulated by P deficiency in stylo roots. Conclusions This study reveals the possible mechanisms underlying the adaptation of stylo to P deficiency. The low-P tolerance in stylo is probably manifested through regulation of root growth, Pi acquisition and cellular Pi homeostasis as well as Pi signaling pathway. The identified genes involved in low-P tolerance can be potentially used to design the breeding strategy for developing P-efficient stylo cultivars to grow on acid soils in the tropics.

Dynamique contrastée de la compaction d’un ferralsol après une défriche mécanisée alternative en Guyane française

Le changement d’usage des terres et l’impact de l’anthropisation sur les milieux forestiers tropicaux sont en progression constante sous les tropiques et en Guyane française. Ces changements sont souvent accompagnés de défriches mécanisées qui favorisent la compaction du sol. Notre objectif était de suivre l’évolution de la compaction du sol d’une parcelle de forêt naturelle exploitée (7 ha) soumise à une défriche mécanisée alternative (itinéraire « chop and mulch », couvert herbacé de Stylosanthes guianensis), puis replantée de quatre espèces forestières commerciales. Sur cet espace présentant finalement diverses couvertures de sol (sol nu, mulch, couvert herbacé), nous avons mesuré la densité apparente jusqu’à 30 cm de profondeur et effectué le test d’infiltration simplifié de Beerkan lors de trois campagnes : avant, juste après et neuf mois après la défriche. Avant la défriche, les sols avaient une très bonne capacité d’infiltration (111 cm/h), étaient peu denses à 0-5 cm de profondeur (0,88) et denses à 25-30 cm (1,19 à 1,40). Juste après la défriche, les sols avaient une capacité d’infiltration très réduite (2 cm/h) et leur couche de surface avait été fortement compactée (1,28) contrairement aux couches plus profondes (1,41 à 1,49). Neuf mois après la défriche, les sols avaient retrouvé une très bonne capacité d’infiltration (149 cm/h), particulièrement sous le couvert herbacé de S. guianensis, et leur couche de surface avait retrouvé une densité proche de l’état initial (1,01), contrairement aux couches plus profondes (1,46 à 1,58). De futures recherches sont nécessaires pour expliquer le retour rapide à l’état initial de la couche de surface et estimer la contribution relative de la macrofaune du sol, des racines et de la fissuration.

Produtividade e características morfogênicas e estruturais da Braquiária Xaraés e do Estilosantes Mineirão

Objetivou-se avaliar a produtividade e as características morfogênicas e estruturais da Brachiaria brizantha cv. Xaraés e do Stylosanthes guianensis var. vulgaris cv. Mineirão na Universidade Federal de Jataí. O delineamento utilizado foi o em blocos completos ao acaso, com dois arranjos de plantio (Xaraés e Estilosantes solteiros e consorciados) associados a três doses de fósforo (70, 105 e 140 kg/ha de P2O5) aplicadas na semeadura, com quatro repetições. A análise dos dados foi realizada em parcela subdividida considerando o efeito do arranjo de plantio, bloco e período de avaliação na parcela e efeito da dose e interação de arranjo de plantio e dose na subparcela. A comparação das médias foi realizada pelo teste t a 5% de probabilidade. A dose 70 kg/ha de P2O5 usada no estabelecimento do pasto foi suficiente para permitir o adequado desenvolvimento do Xaraés e do Estilosantes Mineirão, garantido seu estabelecimento tanto em plantio solteiro quanto consorciado quando a disponibilidade de P no solo é média. A Brachiaria brizantha cv. Xaraés consorciada com Estilosantes Mineirão teve maior produção de matéria seca do que em plantio solteiro e adubada com 50 kg N/ha.

Evaluation on dry forage yields and nutritional characteristics of introduced herbaceous legumes in Myanmar

The study was carried out to evaluate the forage yields, nutritive values and in vitro fermentation parameters of herbaceous legumes. Five varieties of introduced herbaceous legumes; Stylosanthes guianensis cv. Ubon stylo, Macrotyloma axillare cv. Archer, Centrosema brasilianum cv. Ooloo, Stylosanthes guianensis cv. Stylo 184 and Macroptilum bracteatum cv. Cadarga were evaluated at the research farm, University of Veterinary Science, Yezin, Myanmar. No fertilizer and no irrigation were applied for cultivation to test drought resistance. Dry forage yield, nutritive values and gas production at four harvesting times were measured with 4×5 factorial arrangement (5 legumes and 4 harvesting time) in randomized complete block design. There was no interaction between legumes and harvesting time on forage yield, nutritive values and fermentation parameters but they were affected by the main effects of legume types and harvesting time. Among the legume forages, the highest dry forage yields were found in Ooloo, Ubon stylo, and Stylo 184, and followed by the DM yield of Archer and Cadarga. The DM yield of the second harvest was significantly higher (p<0.05) than those of the first, third and fourth harvest which were not significantly different from each other. As a chemical composition, the DM content of Archer was lower (p<0.05) than those of other varieties. Among the legumes forages, the lower CP content was found in Cadarga. The higher NDF was observed in Ooloo. Ooloo, Ubon stylo and Cadarga showed higher ADF in comparison with the other two varieties. Among the harvesting time, the lowest DM content was found at the first harvest. The highest CP content was found at third harvest. The NDF content was not significantly different. The lowest ADF content was found in fourth harvest. According to the dry forage yield, Ubon stylo and Ooloo had the highest dry forage yield and in term of nutritive values, Stylo 184 and Archer had higher nutritive values. As the main effect of forages, Stylo 184 and Archer had higher gas production in comparison with the other varieties. As the main effect of harvesting time, the fourth harvest had the highest gas production in comparison with other harvesting time. It could be better for cultivation by application of fertilizer and irrigation to get more forage yield and quality.

Ruminal degradability of mixtures of Panicum maximum and four forage legume hays in N 'dama steer

This study was conducted to evaluate rumen degradability of Panicum maximum (Panicum) and Lablab purpureus (lablab). Stylosanthes guianensis (stylo). Centrosema pubescens (centro) and Aeschynomene histrix (histrix) harvested from the paddock consisting of grass and herbaceous legumes. Mixtures of P marimum (l. 8g) and each of these legumes (l.2g) were weighed together and incubated in a cannulated steer. Rumen degradability of the Panicum and legume mixtures were studied at 0, 6, 12. 24. 48 and 72 hours using the equation P=a+b (I-e-ct). Average dry matter (DM) and crude protein of the herbaceous legumes were 37.83% DM and 19.86% CP. respectively The soluble fraction. a ofthe DM degradation ranged from 23.34 to 31 rumen degradable fraction, b ranged from 39 46 to 44.43% DM. disappearance rate of substrates C was highest in lablab (12.4%h-1) and stylo (10.2%h-1) Protein degradation characteristics varied significantly (P< 0.05) among the treatments Hlgher b Potential degradability PD and Effective degradability ED. fractions were observed in the sole legumes and grass legumes combinations than the sole grass. This study revealed that hay consisting of grass and legume mixtures was better degraded in terms of DM.CP and fiber fractions in the rumen compared to sole grass hay and this could translate to enhance performance of livestock when fed these mixtures.

Comparative Study on Nutritive Value of Different Legumes Species (Leucaena leucocephala, Calopogononium muconoides and Stylosanthes guianensis)

Legumes are the plant that contains high protein content that has been used as supplementary for animal feed and has a great potential to increase the productivity of livestock. However, no much study has been measured on the nutritive value of legume species. Thus, the aims of this study were to measure the nutritive content in the leaves of three different legume species (Leucaena leucocephala, Calopogonium mucunoides and Stylosanthes guianensis) and to compare the species that contain high of nutritive value. The samples were collected in Tembila area, Besut, Terengganu, then were brought to the Plant Physiology laboratory at UniSZA Kampus Besut for sample preparation. The samples were washed under tap water for 30 seconds to prevent nutrient leaching, then were dried and ground before analyzed by proximate analysis and mineral analysis using Induces Coupled Plasma Optical Emission Spectrometry (ICP-OES) machine. The parameters that were measured by using the proximate analysis consist of dry matter (DM), crude protein (CP), crude fibre (CF), ash, ether extract (EE) and Nitrogen Free Extract (NFE). For mineral analysis, the samples were analyzed for Calcium (Ca), Zinc (Zn), Iron (Fe), Copper (Cu) and Manganese (Mn). The results of this study showed that Leucaena leucocephala had significantly higher (p < 0.05) of CP and EE. While, Stylosanthes guianensis had significantly higher (p < 0.05) of the micro-elements which are Zn, Fe and Mn. Therefore, this study revealed that L. leucocephala contained the highest nutritive value of CP, EE and Calcium.