Desmodium Research Articles

Evaluating local plant species for effective fall armyworm management strategies in Taiwan

BackgroundThe emergence of Spodoptera frugiperda (fall armyworm; FAW) in the world has raised concerns regarding its impact on crop production, particularly on corn and sorghum. While chemical control and Bt crops have been effective in managing FAW damage, the development of pesticide-resistant and Bt-resistant strains necessitates alternative control methods. The push-pull farming system has gained attention, but direct utilization of African plant species in Taiwan faces challenges due to invasive potential and climatic disparities. Therefore, identifying and evaluating suitable local plant species, such as Napier grass (Pennisetum purpureum), Desmodium species, and signal grass (Brachiaria brizantha), is crucial for implementing effective FAW management strategies in Taiwan.ResultsIn screening fifty Napier grass germplasms, all demonstrated an antibiotic effect, reducing leaf consumption compared to corn. Notably, thirty-five germplasms exhibited robust antibiotic traits, decreasing FAW consumption and increasing mortality rates. Three Napier grass germplasms also attracted more female moths for oviposition. Further evaluation of selected Napier grass germplasms and signal grass demonstrated efficacy in reducing FAW larval weight and survival duration. Additionally, Desmodium species, particularly D. uncinatum, showed promising toxicity against FAW larvae.ConclusionOur findings support the effectiveness of selected Napier grass germplasms and signal grass as pull plants, and highlight the potential of D. uncinatum as a push plant in FAW management strategies in Taiwan.

Exploring the Neuroprotective Potential of Desmodium Species: Insights into Radical Scavenging Capacity and Mechanisms against 6-OHDA-Induced Neurotoxicity.

In this study, we collected seven prevalent Taiwanese Desmodium plants, including three species with synonymous characteristics, in order to assess their antioxidant phytoconstituents and radical scavenging capacities. Additionally, we compared their inhibitory activities on monoamine oxidase (MAO) and 6-hydroxydopamine (6-OHDA) auto-oxidation. Subsequently, we evaluated the neuroprotective potential of D. pulchellum on 6-OHDA-induced nerve damage in SH-SY5Y cells and delved into the underlying neuroprotective mechanisms. Among the seven Desmodium species, D. pulchellum exhibited the most robust ABTS radical scavenging capacity and relative reducing power; correspondingly, it had the highest total phenolic and phenylpropanoid contents. Meanwhile, D. motorium showcased the best hydrogen peroxide scavenging capacity and, notably, D. sequax demonstrated remarkable prowess in DPPH radical and superoxide scavenging capacity, along with selective inhibitory activity against MAO-B. Of the aforementioned species, D. pulchellum emerged as the frontrunner in inhibiting 6-OHDA auto-oxidation and conferring neuroprotection against 6-OHDA-induced neuronal damage in the SH-SY5Y cells. Furthermore, D. pulchellum effectively mitigated the increase in intracellular ROS and MDA levels through restoring the activities of the intracellular antioxidant defense system. Therefore, we suggest that D. pulchellum possesses neuroprotective effects against 6-OHDA-induced neurotoxicity due to the radical scavenging capacity of its antioxidant phytoconstituents and its ability to restore intracellular antioxidant activities.

Comparative microbiome diversity in root-nodules of three Desmodium species used in push-pull cropping system.

Desmodium species used as intercrops in push-pull cropping systems are known to repel insect-pests, suppress Striga species weeds, and shift soil microbiome. However, the mechanisms through which Desmodium species impact the soil microbiome, either through its root exudates, changes in soil nutrition, or shading microbes from its nodules into the rhizosphere, are less understood. Here, we investigated the diversity of root-nodule microbial communities of three Desmodium species- Desmodium uncinatum (SLD), Desmodium intortum (GLD), and Desmodium incanum (AID) which are currently used in smallholder maize push-pull technology (PPT). Desmodium species root-nodule samples were collected from selected smallholder farms in western Kenya, and genomic DNA was extracted from the root-nodules. The amplicons underwent paired-end Illumina sequencing to assess bacterial and fungal populations. We found no significant differences in composition and relative abundance of bacterial and fungal species within the root-nodules of the three Desmodium species. While a more pronounced shift was observed for fungal community compositions compared to bacteria, no significant differences were observed in the general diversity (evenness and richness) of fungal and bacterial populations among the three Desmodium species. Similarly, beta diversity was not significantly different among the three Desmodium species. The root-nodule microbiome of the three Desmodium species was dominated by Bradyrhizobium and Fusarium species. Nevertheless, there were significant differences in the proportion of marker gene sequences responsible for energy and amino acid biosynthesis among the three Desmodium species, with higher sequence proportions observed in SLD. There is no significant difference in the microbial community of the three Desmodium species used in PPT. However, root-nodule microbiome of SLD had significantly higher marker gene sequences responsible for energy and amino acid biosynthesis. Therefore, it is likely that the root-nodules of the three Desmodium species host similar microbiomes and influence soil health, consequently impacting plant growth and agroecosystem functioning.

Environmental Effects during Early Life-History Stages and Seed Development on Seed Functional Traits of an Australian Native Legume Species.

Understanding how seed functional traits interact with environmental factors to determine seedling recruitment is critical to assess the impact of climate change on ecosystem restoration. This study focused on the effects of environmental factors on the mother plant during early plant life history stages and during seed development. Desmodium brachypodum A. Gray (large tick trefoil, Fabaceae) was used as a model species. Firstly, this study analyzed seed germination traits in response to temperature and moisture stress. Secondly, it investigated how seed burial depth interacts with temperature and soil moisture to influence seedling emergence traits. Finally, it determined if contrasting levels of post-anthesis soil moisture could result in changes in D. brachypodum reproductive biology and seed and seedling functional traits. The results showed that elevated temperature and moisture stress interacted to significantly reduce the seed germination and seedling emergence (each by >50%), while the seed burial improved the seedling emergence. Post-anthesis soil moisture stress negatively impacted the plant traits, reducing the duration of the reproductive phenology stage (by 9 days) and seed production (by almost 50%). Unexpectedly, soil moisture stress did not affect most seed or seedling traits. In conclusion, elevated temperatures combined with low soil moisture caused significant declines in seed germination and seedling emergence. On the other hand, the reproductive output of D. brachypodum had low seed variability under soil moisture stress, which might be useful when sourcing seeds from climates with high variability. Even so, a reduction in seed quantity under maternal moisture stress can impact the long-term survival of restored plant populations.

Therapeutic Role of Desmodium Species on its Isolated Flavonoids.

Secondary metabolites are an important part to play a major role in society and it was isolated from plant flavonoids and useful in the treatment of various kinds of diseases in the human race. They are widely used as food and nutrition supplements as well as antioxidants. Traditionally, the Desmodium species are an important tool for the secondary metabolites to treat various diseases. Desmodium triquetrum (Fabaceae) one of the Indian medicinal plants is widely used in the treatment of asthma and inflammation. Three flavonoids isolated from Desmodium triquetrum Linn namely Baicalein, Naringin and Neohesperidin are useful as antioxidants, food and nutrition supplements, that help the body to function efficiently while protecting it against toxins as well stressors. The role of flavonoids may be due to the presence of the phenolic compound. Similarly, the flavonoids such as gangetin, gangetinin, desmocarpin and desmodin isolated from the species Desmodium gangeticum are responsible for antileishmanial, antioxidant, anti-arthritic, and immunomodulatory activities. Additionally, isolated flavanoids from the species Desmodium triflorum show antibacterial, antiepileptic, antifungal, and radioprotective activities. So, the aim of the present study, based on the literature miming from the desmodium species is to acknowledge the importance of flavonoids in human health as dietary food supplements and therapeutic uses.

Cytotoxicity, Antioxidant Activities, GC-MS and HPLC Fingerprint Analyses of Different Extracts of Desmodium tortuosum (Sw.) DC

The family Fabaceae is the third-largest flowering plant family, and the genus Desmodium has exhibited a wide range of biological activities and a variety of chemical constituents. In the present study, different extracts of Desmodium tortuosum were evaluated for their cytotoxic and antioxidant activities, as well as their total phenolic content (TPC). The antioxidant activities were estimated using the 1,1'-diphenyl-2-picraylhydrazyl free radical (DPPH), while the cytotoxic activity was evaluated via the brine shrimp lethality test (BSLT). The antioxidant activity results revealed that the DPPH radical scavenging activity (SC50) ranged from 1.12 to 61.22 µg/ml with respect to ascorbic acid (SC50 = 7.45 µg/ml). Among all tested fractions, 90% methanol was the most active. On the other hand, the cytotoxic activities were arranged as follows: n-BuOH (LC50 = 310), EtOAc (LC50 = 350), and 70% methanol (LC50 = 380). High-Performance Liquid Chromatography-Fingerprint analyses were used to determine the chemical composition and relative proportions of phenolic compounds. GC-MS analysis indicated the presence of fatty acids and other compounds. The major identified compounds were Benzene (1-butyloctyl) (11.88%) and Himachalene <α-> (11.08%) for the ethyl acetate extract and 10-Undecenoic acid, methyl ester (25.50%) for unsaponifiable matter.

Traditional medicinal uses and biological activities of species of the genus Desmodium: a literature review

The genus Desmodium includes about 350 species, distributed in tropical and subtropical regions around the world. The objective of this review was to associate the traditional medicinal uses of the genus Desmodium with its biological activities reported in the scientific literature. Traditional medicinal uses and biological activities were described in 56 species. More than 100 traditional medicinal uses have been reported in 43 countries, highlighting the use in inflammatory, gastrointestinal and infectious processes, muscular pain, rheumatic, renal and hepatic affections. Among the 45 biological activities experimentally evaluated, antioxidant, antimicrobial, anti-inflammatory, hepatoprotective and antinociceptive were the most reported. The species with the highest number of studies were D. gangeticum, D. adscendens and D. styracifolium. In conclusion, several traditional medicinal uses have been experimentally supported, demonstrating the pharmacological potential of this genus.

Ticktrefoil (Desmodium) species as a nutraceutical forage resource for animals

AbstractTicktrefoil (Desmodium) species from the USDA, ARS, Plant Genetic Resources Conservation Unit (PGRCU) germplasm collection in Griffin, GA, were evaluated for their potential livestock nutraceutical (nutritional + pharmaceutical) value in a field small plot study at the Fort Valley State University (FVSU) Agricultural Research Station, Fort Valley, GA. Horse marmalade (Desmodium discolor Vogel), greenleaf ticktrefoil (Desmodium intortum [Mill.] Urb.), panicledleaf ticktrefoil (Desmodium paniculatum [L.] DC.), Hawaii ticktrefoil (Desmodium sandwicense E. May) and twisted ticktrefoil (Desmodium tortuosum [Sw.] DC.) were established in a greenhouse and transplanted to field plots, with plant material from each species harvested, freeze‐dried, ground and analyzed for nutrient content and bioactivity. Crude protein (CP) levels in D. discolor and D. tortuosum averaged 233 g/kg, whereas CP in D. intortum, D. paniculatum and D. sandwicense ranged from 99 to 157 g/kg. The Desmodium species had in vitro true digestibility values of 755 to 878 g/kg. There were no detectable condensed tannins in D. discolor and D. tortuosum, whereas D. intortum, D. paniculatum and D. sandwicense averaged 88, 89 and 73 g/kg total condensed tannin, respectively. There were species differences in flavonoid content (p < .01), with the highest delphinidin and cyanidin concentrations in D. sandwicense and D. paniculatum, respectively. There were no detectable levels of delphinidin or cyanidin for D. discolor or D. tortuosum. Quercitin and kaempferol concentrations were highest in D. intortum and D. paniculatum, respectively, whereas D. discolor and D. tortuosum had the lowest values. The highest protein precipitable phenolics and total phenolic concentrations were for D. paniculatum. Desmodium species have potential as nutraceutical forage for livestock and warrant further investigation.

In vitro and in vivo antimicrobial activities of extracts and constituents derived from Desmodium styracifolium (Osb.) Merr. against various phytopathogenic fungi and bacteria

Phytopathogenic fungi and bacteria pose a threat to plant health and cause large losses in crop quality and production. Currently, green methods for controlling phytopathogenic fungi and bacteria have been paid attention to. In this study, in vitro and in vivo antimicrobial activities of Desmodium styracifolium and its metabolites against phytopathogenic fungi and bacteria were investigated to find a new solution for the green method. The result showed the crude extract of D. styracifolium exerts a potent suppression against fungal plant diseases in vivo. At 3000 µg/mL, n-hexane and dichloromethane-soluble extracts of D. styracifolium effectively controlled rice blast (84.6% and 53.8%) and tomato late blight (67.7% and 61.3%), respectively. Using in vitro antifungal bioassay-guided fractionation, sixteen compounds were isolated and identified. The occurrence of isoflavanones 5 and 7 in D. styracifolium, as well as pyrrole lactone alkaloid 14 in the genus Desmodium was firstly reported. Compound 9, a new isoflavone isolated from nature, displayed potent antifungal and antibacterial activities in vitro. The two remarkable bioactive groups of isoflavanones (5–7) and isoflavones (8–10) were determined as antifungal constituents from D. styracifolium with a wide-spectrum antifungal activity. Magnaporthe oryzae and Phytophthora species were susceptible to the isoflavonoid groups. Especially, in a range of 125–500 µg/mL, isoflavonoids 5 and 10 effectively inhibited M. oryzae in both in vitro and in vivo experiments. Compounds 5, 6, 8–11 significantly suppressed the bacterial growth of Acidovorax avenae subsp. cattlyae in vitro. Among them, 5 (IC50 = 33.1 µg/mL) and 9 (IC50 = 42.2 µg/mL) were the best inhibitors against A. avenae subsp. cattlyae. Our findings indicate that the isoflavanones and isoflavones of D. styracifolium are worthy of further consideration as lead molecules to develop a new class of inhibitors against phytopathogenic fungi and bacteria.

Performance of Push–Pull Technology in Low-Fertility Soils under Conventional and Conservation Agriculture Farming Systems in Malawi

Push–pull technology (PPT) is one of the most viable low-cost agroecological practices that reduces the effects of insect pest infestations (e.g., stemborer) and parasitic weeds (e.g., Striga) in croplands. PPT was evaluated in low-fertility soils and two farming practices, minimum-tilled conservation agriculture practice (CA), and conventionally tilled practice (CP), in contrasting agroecological zones at the Chitedze, Mbawa, and Chitala stations in Malawi. Stemborer and Striga infestations were also investigated and the suitability levels of two Desmodium species. Farmers’ perceptions of PPT were gathered through a focus group discussion. The performance of PPT varied significantly between treatments, sites, and years on grain yields and the number of cobs that could be assigned to soil attributes. Significant variations were found in the number of exit holes, stemborer damage severity, and the number of Striga-affected plants with severe infestation. In Chitedze, CP recorded significantly shorter maize plants by 14.1, 11.6, and 5.8 cm than CP–PP, CA, and CA–PP, respectively, in 2016–2017. There were no significant differences in plant height between CP–PP, CA, and CA–PP. Similar results were also found in 2017–2018. Focus group discussions among farmers attested to up to 70% reductions in Striga weed and stemborer pests under PPT over the two seasons. Farmers who used push–pull technology reported a 45–50% yield increase. Push–pull was also perceived as a technology that improves soil fertility and controls soil erosion. The study presented the importance of soil physicochemical properties in the performance of the technology, as supported by the high occurrence of Striga asiatica in the country and the low suitability of Greenleaf Desmodium. Results reaffirmed the technology’s agronomic benefits in productivity, pest management, plant vigour, and Striga control. The cost of labour was described as a challenge, and research to identify more suitable Desmodium species is needed. The current study suggests the release of the technology in Malawi, emphasizing the inclusion of Desmodium and Brachiaria as animal fodder for the adoption of the technology.

Perennial legume intercrops provide multiple belowground ecosystem services in smallholder farming systems

Soil degradation is a major underlying cause of poverty and malnutrition in smallholder agrarian communities across the globe. Legume diversification, through polyculture or intercropping, is a strategy that increases yields and income while improving family nutrition. However, the potential for these legume-cereal intercrops to restore soil functions in smallholder fields remains uncertain, with many studies failing to detect increases in soil organic matter (SOM). In sub-Saharan Africa, smallholders typically grow maize either intercropped with short-lived annual food legumes or as a monoculture. Recently, a novel maize system which includes perennial legumes in the genus Desmodium as intercrops, known as “push-pull” (hereafter, PP) has been increasingly adopted by smallholders across the region. The yield, nutritional and economic benefits of the PP system are well-documented. We investigated the effects of PP maize intercropping on soil fertility compared to the predominant maize culture systems (hereafter, NPP) using soils from long-term experiments and smallholder fields in western Kenya. Maize-desmodium intercrops promoted SOM accrual and increased plant available phosphorus. In the long-term research station experiments soil organic N was 20% greater and labile organic N reserves were five-fold greater in PP compared to NPP soils. Despite equal P fertilizer application rates, extractable soil P was two-fold greater in PP compared to NPP soils. Soils under maize-food legume intercrops did not show any detectable accrual of SOM compared to maize monocultures. Soil benefits in smallholder PP fields tended to mirror those found in the controlled experiments. Taken together, our results demonstrate that the perennial legumes in PP system restore soil function and fertility. Developing additional well-designed intercropping systems that include perennial legumes could play a significant role in reversing the trajectory of soil degradation in smallholder farming systems while enhancing human well-being.

English

The aim of this research was to evaluate the capacity of symbiotic efficiency of native rhizobia from soils of the state of Rio Grande do Sul (RS), Brazil in Phaseolus lunatus L. plants. Soil and nodule samples from predominant legume plants such as Desmodium species were collected in seven locations of the state of RS. For the isolation of the rhizobia from the soil samples, lima bean “olho de cabra preto” variety and “leucena” (Leucena leucocephala) and plants were used as baits. Subsequently, the symbiotic characterization of the isolates was performed by inoculation on lima bean plants in vitro conditions. The selected bacterial isolates were evaluated for biological nitrogen fixation efficiency in a greenhouse experiment, being determined after: shoot dry mass, root dry mass, nodule dry mass, nitrogen (N) accumulated shoot and calculated the N fixation relative efficiency index. Among the 28 rhizobia isolates tested, 11 induced nodule formation in lima bean. The rhizobia Plu03 and Plu14 stimulated a greater increase of plant dry mass, nodule dry mass and nitrogen accumulation in the shoot, reflecting in a higher relative efficiency index. These results suggest that the isolates Plu03 and Plu14 are more efficient in promoting growth of lima bean, which could be recommended for future agronomic efficiency studies. Key words: Rhizobia, lima bean, biological nitrogen fixation.

Effect of dry heat on seed germination of Desmodium and Stylosanthes species

Mechanical scarification with a scalpel is the best treatment to break physical dormancy and reach high germination percentages in many legumes. However, it is highly time-consuming. Given the ecological relationship between the presence of physical dormancy and high temperatures in tropical grasslands, dry heat treatment could also promote breaking of physical dormancy in Desmodium and Stylosanthes species. This study assessed seed germination of several accessions of nine species of Desmodium and Stylosanthes. Seeds were treated with dry heat (80°C for 30 minutes) and scarified with a scalpel to determine whether dry heat is a reliable alternative treatment to overcome physical dormancy. Mechanical scarification with a scalpel was effective and resulted in high germination for all species. In S. guianensis, both treatments had an equivalent effect, making dry heat a feasible alternative. Dry heat could also be a reliable alternative in D. heterocarpon, D. velutinum, S. hamata, and S. scabra, but tetrazolium tests may be necessary to confirm viability. For D. barbatum and D. scorpiurus, dry heat could be an alternative but further research is needed to confirm this, while in S. capitata and S. viscosa dry heat is not a reliable alternative.

APLIKASI Desmodium ovalifolium YANG DIINOKULASI FUNGI MIKORIZA ARBUSKULA PADA BIBIT Octomeles sumatrana Miq. DI TANAH PASCA TAMBANG

Mining activities resulted on environmental degradation and ecosystem damage. Legume cover crop forming symbiosis with beneficial soil microorganism is widely well known to be used for degraded land reclamation such as in post mining area. Desmodium spp. is one of legume cover crop forming symbiosis with arbuscular mycorrhizal fungi (AMF) and rhizobium. This study aimed: (1) to isolate and characterize AMF collected from rhizosfer of 4 species of Desmodium spp. grow in gold mining of PT. Cibaliung Sumberdaya, Banten; (2) to study the growth of Octomeles sumatrana planted together with D . ovalifolium inoculated with AMF. Soil collected from post mining was used as growth media. There were two factors in this study: AMF inoculation and compost treatment s . Based on morphological characteristics after culture breeding , there were 23 spesies of Glomus sp. and 3 spesies of Acaulospora sp. isolated from 4 spesies of Desmodium spp. collected in PT. Cibaliung Sumberdaya. Inoculation of AMF and compost application increased height of O . sumatrana in two week s after planting. Single inoculation of AMF into O. sumatrana improved height and increased number of spore as well. Combination of compost with post mining soil had the highest increased in height, diameter, total biomass, roots biomass, and sprout biomass of O . sumatrana .

<p><strong>A new combination and lectotypification in the genus <em>Desmodium</em> (Papilionoideae: Desmodieae) of Mexico</strong></p>

During the review of the genus Desmodium for the different regional floras of Mexico, we have identified problems of nomenclature and typification such as the case of Meibomia karwinskii, wrongly cited in the list of Legumes of Oaxaca as Desmodium karwinskii and thus invalidly published. Also, in this list the attached illustration exhibits incorrect interpretations on its floral characters that does not agree with usage of this species. In this proposal, the nomenclature of the species name is discussed and justified here the designation of a lectotype and three isolectoypes. In addition, a more detailed description of the species is given based on recent field collections and illustrated with images of the habit and morphological characters.

Cultivation of native plants for seed and biomass yield

AbstractEstablishing native perennial plants on the agricultural landscape can improve ecosystem services and provide marketable products, such as seed for restoration plantings and biomass for renewable energy. Native perennials of economic and ecological interest should be examined in different planting configurations over time to determine their suitability for sustained production. Canada milk vetch (Astragalus canadensis L.), purple coneflower (Echinacea purpurea L.), and showy tick trefoil (Desmodium canadense L.) were established at two locations in Minnesota to evaluate seed and vegetative biomass yields. These forbs were established in six different agronomic designs: three strip designs (one‐row, three‐rows, and six‐rows) and three community designs (monoculture, low‐richness polyculture, and high‐richness polyculture). Seed yield averaged 2995, 950, and 1157 kg ha−1 for Canada milk vetch, purple coneflower, and showy tick trefoil in the first year and declined for all species over time. Biomass yields averaged 6743, 2725, and 2869 kg ha−1 in the first year for Canada milk vetch, purple coneflower, and showy tick trefoil, respectively. Canada milk vetch biomass yields declined by 98% over time, and showy tick trefoil biomass yields increased by 40%. Seed and biomass yields were the lowest in one‐row strip design and greatest in the community designs, with little difference between monocultures and polycultures. Results suggest that production is maximized in community designs and that purple coneflower and showy tick trefoil have the potential for multiyear yields.

Description and complete genome sequences of Bradyrhizobium symbiodeficiens sp. nov., a non-symbiotic bacterium associated with legumes native to Canada.

Four bacterial strains isolated from root nodules of soybean plants that had been inoculated with root-zone soil of either Amphicarpaea bracteata (Hog Peanut) or Desmodium canadense (Showy Tick Trefoil) growing in Canada, were previously characterized and placed in a novel lineage within the genus Bradyrhizobium . The taxonomic status of the novel strains was verified by genomic and phenotypic analyses. Phylogenetic analyses of individual and concatenated housekeeping gene sequences (atp D, gln II, rec A, gyr B and rpo B) placed all novel strains in a highly supported lineage distinct from named Bradyrhizobium species. Data for sequence similarities of concatenated housekeeping genes of novel strains relative to type strains of named species were consistent with the phylogenetic data. Average nucleotide identity values of genome sequences (84.5–93.7 %) were below the threshold value of 95–96 % for bacterial species circumscription. Close relatives to the novel strains are Bradyrhizobium amphicarpaeae , Bradyrhizobium ottawaense and Bradyrhizobium shewense . The complete genomes of strains 85S1MBT and 65S1MB consist of single chromosomes of size 7.04 and 7.13 Mbp, respectively. The genomes of both strains have a G+C content of 64.3 mol%. These strains lack a symbiosis island as well as key nodulation, nitrogen-fixation and photosystem genes. Data from various phenotypic tests including growth characteristics and carbon source utilization supported the sequence-based analyses. Based on the data presented here, the four strains represent a novel species for which the name B radyrhizobium symbiodeficiens sp. nov., is proposed, with 85S1MBT (=LMG 29937T=HAMBI 3684T) as the type strain.

Pollination biology and breeding system of Desmodium grahamii (Fabaceae, Papilionoideae): functional aspects of flowers and bees

This study aims to understand the role of floral traits in determining the pollination and reproduction of Desmodium grahamii (Fabaceae, Papilionoideae) with explosive floral mechanism in populations occurring in a natural reserve and botanical garden in southern Mexico City. We assessed the breeding system by quantifying floral and pollinator activity, compatibility, pollination, and reproductive success, assisted by field and laboratory analyses. Results showed that cross-pollination and self-pollination coexist, but bees are required for fruit and seed set. Flower colour is the primary attractant. Floral scent is also likely important because the petals were covered with papillae, although no scent was perceptible. Morphological and functional observations of D. grahamii exhibit simultaneous pollen release and stigma receptivity when the flower is activated by a pollinator and there is no secondary pollen presentation; this contrasts with what has been reported on other species of Desmodium. Pollen is the pollinators’ only reward, and its deposition and collection must be done synchronically, occurring when a bee lands and introduces its proboscis in the flower. In this study, we identified seven floral visitors: five bee pollinators and two syrphid flies as pollen thieves. On some occasions, Apis mellifera also behaves as a pollen thief. Fruit and seed set of flowers that were isolated from visitors may indicate a delayed pollination mechanism. Pollination results also suggest that Apis bees and syrphid flies may contribute to fruit and seed production when they forage on flowers at post-anthesis.

Desmodium amplistipulaceum (Leguminosae, Papilionoideae), a new species from northwest region of Chiapas, Mexico

Desmodium amplistipulaceum, a new species from the evergreen tropical forest of La Sepultura Biosphere Reserve, Chiapas, is described and illustrated. Morphologically it is very similar to Desmodium helleri, but it differs from this by persistent and widely ovate stipules; inflorescences in simple racemes and slightly hirsute sessile loments with 4 or 5 articles. It includes a morphological description, map of distribution and comparative photographs of the calyx, trichomes of calyx and gynoecium and stigma for both species, as well as an identification key to differentiate all the Desmodium species from La Sepultura, Chiapas.

Plastid genome evolution in tribe Desmodieae (Fabaceae: Papilionoideae).

Recent plastid genome (plastome) studies of legumes (family Fabaceae) have shown that this family has undergone multiple atypical plastome evolutions from each of the major clades. The tribe Desmodieae belongs to the Phaseoloids, an important but systematically puzzling clade within Fabaceae. In this study, we investigated the plastome evolution of Desmodieae and analyzed its phylogenetic signaling. We sequenced six complete plastomes from representative members of Desmodieae and from its putative sister Phaseoloid genus Mucuna. Those genomes contain 128 genes and range in size from 148,450 to 153,826 bp. Analyses of gene and intron content revealed similar characters among the members of Desmodieae and Mucuna. However, there were also several distinct characters identified. The loss of the rpl2 intron was a feature shared between Desmodieae and Mucuna, whereas the loss of the rps12 intron was specific to Desmodieae. Likewise, gene loss of rps16 was observed in Mucuna but not in Desmodieae. Substantial sequence variation of ycf4 was detected from all the sequenced plastomes, but pseudogenization was restricted to the genus Desmodium. Comparative analysis of gene order revealed a distinct plastome conformation of Desmodieae compared with other Phaseoloid legumes, i.e., an inversion of an approximately 1.5-kb gene cluster (trnD-GUC, trnY-GUA, and trnE-UUC). The inversion breakpoint suggests that this event was mediated by the recombination of an 11-bp repeat motif. A phylogenetic analysis based on the plastome-scale data set found the tribe Desmodieae is a highly supported monophyletic group nested within the paraphyletic Phaseoleae, as has been found in previous phylogenetic studies. Two subtribes (Desmodiinae and Lespedezinae) of Desmodieae were also supported as monophyletic groups. Within the subtribe Lespedezinae, Lespedeza is closer to Kummerowia than Campylotropis.