Medicago Polymorpha Research Articles

Salinity tolerance and avoidance mechanisms at germination among messina (

Messina (Melilotus siculus) cv. Neptune, an annual pasture legume native to the Mediterranean Basin, has recently been released for saltland pastures in southern Australia following demonstration of biomass production and persistence superior to other commercial pasture legumes in saline environments prone to winter waterlogging. Self-regenerating annual pasture legumes also require seed adaptations for both tolerating and avoiding salinity at germination in these environments. This study examined diversity within Neptune and 20 other messina accessions for salt tolerance at germination, recovery of germinability from temporary salt stress, and timing and extent of hardseed softening, compared with balansa clover (Trifolium michelianum) cv. Frontier, burr medic (Medicago polymorpha) cv. Scimitar and white melilot (Melilotus albus) cv. Jota. Germination rates after 14 days at 300 mM NaCl relative to 0 mM NaCl were ≥99% for Neptune and 18 other messina accessions, 66% for Scimitar, 21% for Jota and 11% for Frontier. No genotype germinated at 600 mM NaCl; however, when transferred to 0 mM NaCl after 14 days at 600 mM, all genotypes except Scimitar and Jota recovered partial germination, ranging from 13% to 93% of controls (0 mM NaCl for 28 days). The softening rate of hard (impermeable) seeds in the field varied among genotypes, with deferral of hardseed softening until late autumn–early winter, when rainfall is more likely, indicating greater persistence. The months in which the hardseed level first became significantly lower than the initial level (in freshly harvested seeds) after placement on the soil surface in December were: March for Frontier; April for Scimitar, Jota and Neptune; and March–July for all messina accessions. This study confirmed that messina has high salt tolerance and several avoidance mechanisms at germination that contribute to its adaptation to saline soils in southern Australia. Several messina accessions were superior to Neptune for individual traits which could be exploited for plant breeding. These results also have implications for saltland pastures in other regions of the world with Mediterranean-type climates.

Genetic analysis of boron tolerance in burr medic (

Soils with toxic levels of boron (B) are widespread in the cereal-livestock zone of southern Australia. The annual pasture legume burr medic (Medicago polymorpha L.) is widely grown in rotation with grain crops in this zone, but current cultivars are susceptible to high levels of B. We tested the boron tolerance of several putative B tolerant burr medic accessions and developed four F2 populations by crossing two tolerant accessions with two susceptible cultivars. We tested a B tolerance SSR marker developed for barrel medic (M. truncatula Gaernt) on tolerant burr medic accessions but found a new marker was required. We identified several B tolerant burr medic accessions. In our four F2 populations tolerance was inherited in a 3 : 1 (tolerant : susceptible) ratio and we identified a molecular marker that accounts for 0.84 of the variation. The B tolerant accessions, along with the B tolerance marker, will allow for the efficient introgression of B tolerance into widely adapted genetic backgrounds and will allow breeders to efficiently develop cultivar(s) that are tolerant of a widespread subsoil constraint.

Oviposition preferences of the native budworm,

The native budworm, Helicoverpa punctigera (Wallengren), is an important economic insect pest of cotton and other crops. It is widely distributed in Australia and has been recorded on a range of host plants including native, non-crop hosts in inland regions. To date, there are few records of its occurrence on plants with the C4 photosynthetic pathway. Here, we assessed the oviposition preferences of H. punctigera for naturally occurring C3 and C4 plants under glasshouse conditions, to establish their potential as hosts. We conducted bioassays on two C4 plants, saltbushes Atriplex nummularia Lindl. and Atriplex vesicaria Heward ex Benth.; and two C3 plants, legumes Medicago polymorpha L. (burr medic) and Cullen cinereum (Lindl.) J.W.Grimes (annual verbine). The two C4 plants attract egg laying in the field; however, C3 plants are the preferred hosts. Ovipositing females showed a preference for the C3 over the C4 plants but oviposition occurred on both. Of the C4 plants, females preferred to oviposit on A. nummularia (77%) over A. vesicaria (24%) in both a multi- and two-choice test. In addition, ovipositing females preferred the upper leaf surface of A. nummularia (68%) and the under leaf surface of A. vesicaria (64%) as their oviposition site. Our findings suggest that under field conditions, when C4 plants such as saltbushes grow near C3 plants, as occurs in inland regions, the C4 plants could receive eggs along with the C3 plants, enabling the initial stages of larval recruitment to occur in C3 plants.

Exogenous ACC Deaminase Is Key to Improving the Performance of Pasture Legume-Rhizobial Symbioses in the Presence of a High Manganese Concentration.

Manganese (Mn) toxicity is a very common soil stress around the world, which is responsible for low soil fertility. This manuscript evaluates the effect of the endophytic bacterium Pseudomonas sp. Q1 on different rhizobial-legume symbioses in the absence and presence of Mn toxicity. Three legume species, Cicer arietinum (chickpea), Trifolium subterraneum (subterranean clover), and Medicago polymorpha (burr medic) were used. To evaluate the role of 1-aminocyclopropane-1-carboxylate (ACC) deaminase produced by strain Q1 in these interactions, an ACC deaminase knockout mutant of this strain was constructed and used in those trials. The Q1 strain only promoted the symbiotic performance of Rhizobium leguminosarum bv. trifolii ATCC 14480T and Ensifer meliloti ATCC 9930T, leading to an increase of the growth of their hosts in both conditions. Notably, the acdS gene disruption of strain Q1 abolished the beneficial effect of this bacterium as well as causing this mutant strain to act deleteriously in those specific symbioses. This study suggests that the addition of non-rhizobia with functional ACC deaminase may be a strategy to improve the pasture legume–rhizobial symbioses, particularly when the use of rhizobial strains alone does not yield the expected results due to their difficulty in competing with native strains or in adapting to inhibitory soil conditions.

Legume Ecotypes and Commercial Cultivars Differ in Performance and Potential Suitability for Use as Permanent Living Mulch in Mediterranean Vegetable Systems

Weed control in organic conservative vegetable systems is extremely challenging and the use of legume permanent living mulches (pLM) presents an interesting opportunity. The successful use of pLM is largely determined by the choice of appropriate legumes which are able to combine adequate weed control with a marginal competitive effect on the cash crop(s). However, the availability of legumes for such systems is limited and their characterization based on growth traits can support the selection of suitable legumes for conservation organic vegetable systems. The current study investigated weed control capacity and variability in morphological and phenological traits relevant in inter-plant competition among a range of 11 commercial cultivars of legumes and seven ecotypes of Medicago polymorpha (bur medic). For commercial cultivars, Lotus corniculatus (bird’s-foot trefoil) and Trifolium repens (white clover) showed the best weed control capacity, while Trifolium subterraneum (subterranean clover) and Medicago polymopha had more suitable characteristics for a rapid and complete establishment of the pLM. Overall, legume mulches appear more effective in dicotyledonous than in monocotyledonous weed control. Trifolium subterraneum cv. Antas and T. repens cv. Haifa were identified as the potentially most suitable legumes for use as pLM and their use in mixtures could be a promising solution. In addition, the ecotypes of Medicago polymorpha Manciano and Talamone proved to be well adapted for local environmental conditions and they showed a better weed suppression than the commercial cultivars of Medicago polymorpha.

Microbial mutualist distribution limits spread of the invasive legume Medicago polymorpha

The spread of invasive species can be limited or promoted by the distributions of mutualists, which presents an opportunity for managing biological invasions. However, the ways in which the geographical distributions of mutualists shape the range limits and invasion dynamics of introduced species remains unclear. Legumes include noxious invaders whose success is tied to their mutualism with nitrogen-fixing rhizobium bacteria. We examine whether the availability of compatible rhizobia limits the spread of an invasive legume at both small (50 m) and large (United States) spatial scales across natural invasion fronts. Using greenhouse experiments we simulated the dispersal of Medicago polymorpha into soils at increasing distances from a host patch. We find that rhizobial mutualist availability rapidly declines to almost zero within 20 m of established legume patches and legume fitness and the percentage of leaf nitrogen derived from symbiotic nitrogen fixation show a concomitant decline. The decline of fitness due to the lack of rhizobium mutualists differs among M. polymorpha genotypes. Our findings support the missed mutualist hypothesis whereby mutualist limitation reduces invasiveness. As M. polymorpha colonizes novel areas, seeds following either short- (50 m) or long-range seed dispersal will be mutualist-limited and exhibit low fitness and nitrogen fixation. Without co-introduction via transport of soil containing both mutualists, the patchy distribution of E. medicae may limit M. polymorpha invasion. Plant lineages exhibit genetic variation upon which selection could act to reduce dependence on rhizobia, thus a scarcity of symbionts could cause plant symbiosis traits to evolve during invasion.

Interseeding cover crops into maize: Characterization of species performance under Mediterranean conditions

Cover crop (CC) benefits and adoption in crop rotations may be limited by the short planting window after the cash crop. Interseeding or relay intercropping of CC is a technique that could overcome short planting windows constraints and allow CC establishment and growth. However, in Mediterranean regions this technique has been poorly implemented.Field experiments were established in Central Spain during two consecutive growing seasons to assess the performance of different species as interseeded crops into irrigated maize (Zea mays L.). The treatments included annual ryegrass (Lolium multiflorum L.) and eight legumes: burr medic (Medicago polymorpha L.), barrel medic (Medicago truncatula L.), yellow sweetclover (Melilotus officinalis L.), berseem clover (Trifolium alexandrinum L.), balansa clover (Trifolium michelanium L.), red clover (Trifolium pratense L.), Persian clover (Trifolium resupinatum L.), and common vetch (Vicia sativa L.). A bare soil was included as control treatment. After the maize harvest, the four species with the best performance were planted as autumn cover crops in adjacent plots. The ground cover was studied throughout the experimental period, and biomass and N content for each species were determined in the autumn and in the following spring prior to the cover crop termination. The soil inorganic N content was determined in spring.Barrel medic, yellow sweetclover, common vetch and annual ryegrass were the species with the best performance in terms of soil coverage during the summer. Red clover and Persian clover had good establishment in one out of two years. None of the interseeded species impaired maize grain yield or quality. Interseeded species achieved better soil coverage and increased the biomass accrued at autumn compared to cover crops sown in October. Therefore, interseeded species ensured longer ground coverage, increasing the potential for soil quality improvement or weed suppression. Moreover, the higher biomass achieved by interseeded species ensured the survival of yellow sweetclover, which was winter killed when planted in the autumn. Interseeded cover crops enhanced the potential of N leaching reduction compared to autumn cover crops.This experiment confirms the suitability of different species interseeded in summer into irrigated maize in Mediterranean regions, and highlights the extra benefits of this practice in annual rotations.

Effect of Groundcovers on Reducing Soil Erosion and Non-Point Source Pollution in Citrus Orchards on Red Soil Under Frequent Heavy Rainfall

Periods of consecutive days with heavy rain of high intensity are common in the red soil region of China, increasing unpredictable risks of soil erosion and non-point source pollution on sloping orchards. Grass cover, as a type of vegetation management, is useful for controlling soil erosion and pollution. However, the potential of different kinds of groundcover plants in combating soil erosion and non-point source pollution remains unclear under the rainfall conditions in this region of China. This study included 7 d of simulated rainfall applied to a set of six treatments: Bare soil control, natural grass, and four groundcover treatments, Trifolium repens, T. repens, and Lolium perenne, Vicia sativa and Festuca elata, Medicago polymorpha, and Cynodon dactylon. The effects of the treatments on runoff volume, and soil, nitrogen, and phosphorus losses were evaluated. The results indicated that greater soil erosion and non-point source pollution occurred over the first 3d of daily 1-h simulated rainfall events. Also, the beneficial effects of the groundcover plants were greater earlier in the 7-d period of daily heavy rain, particularly in reducing runoff and nitrogen loss on the second and third day. Compared with bare soil, all the groundcovers showed a reduction effect in varying degrees, among which T. repens treatment was more effective. T. repens treatment showed an overall reduction in runoff and soil loss by 25.5% and 91.5%, respectively, and total nitrogen, nitrate nitrogen, ammonia nitrogen and total phosphorus loss by 25.5%, 74.6%, 90.7%, and 81.8%, respectively. These findings indicated that single planting of perennial pasture T. repens with short stems is an effective management option to limit soil erosion and non-point source pollution in sloping citrus orchards of southern China.

Author's Correction: Stress Tolerance and Symbiotic and Phylogenic Features of Root Nodule Bacteria Associated with Medicago Species in Different Bioclimatic Regions of Tunisia.

Thirty two rhizobial isolates were obtained from different bioclimatic regions of Tunisia using as trap plants, Medicago sativa, Medicago ciliaris, Medicago polymorpha and Medicago minima. To study their diversity and characterize them in relation to Mediterranean conditions, abiotic stress resistance, symbiotic properties and genetic diversity in terms of 16S rRNA and nodA sequences were assessed. Five isolates from M. sativa, three from M. ciliaris and three from M. minima could grow at 45°C. Only two isolates from M. sativa grew at 4% NaCl. The most stress tolerant isolates were obtained from arid soils. A phylogenetic analysis of 16S rRNA genes revealed 29 isolates to be closely related to Ensifer including one (Pl.3-9) that showed a 16S rRNA sequence similar to that of Ensifer meliloti and nodA sequence similar to that of Ensifer medicae. However, three isolates were categorized into Agrobacterium containing the nodA of Ensifer. Furthermore, these isolates developed nodules on original hosts. The results for the four isolates suggest horizontal gene transfer between the species.

Floristic Composition and Diversity in Plots of Early Post-Agricultural Succession in Four Agroecosystems in the District of Cajatambo, Lima

In this paper, the floristic composition is studied in plots of early post-agricultural succession induced in four agroecosystems (Ocopata, Rancas, Tupicocha and Ucupi) in the district of Cajatambo, Lima. The plots are located between 2,992 masl and 4,220 masl in three plant formations (agriculture, scrubland and grassland), and the description of the floristic composition was made before and after inducing the succession between 2015 and 2017. The number of determined plants is 78, all of which belong to 30 botanical families, of which the Asteraceae (16 species), Fabaceae (11 species) and Poaceae (8 species) families stand out. Indeed, the only common species among the four agroecosystems is Medicago polymorpha ; moreover, five species appear in three of the four agroecosystems: Brassica rapa subsp. campestris and Verbena litoralis (Ocopata, Tupicocha and Rancas), Oenothera rosea and Trifolium repens (Ocopata, Rancas and Ucupi) and Bidens andicola (Tupicocha, Rancas and Ucupi).

Palynological investigation of some selected species of family Fabaceae from Pakistan, using light and scanning electron microscopy techniques.

Pollen morphology of 11 species of family Fabaceae that is, Trifolium alexandrinum, Trifolium resupinatum, Arachis hypogaea, Lathyrus aphaca, Medicago lupulina, Vicia sativa, Lathyrus odoratus, Pongamia pinnata, Melilotus indicus, Medicago polymorpha, Medicago sativa from Pakistan has been investigated by light and scanning electron microscopy. Pollen were generally tricolporate, radially symmetrical, isopolar, elliptic in equatorial view and triangular in polar view under LM. Results showed that pollens were per-prolate (T. alexandrinum), prolate (T. resupinatum, V. sativa, L. odoratus, Melilotus indicus, M. polymorpha, M. sativa) and sub-prolate (A. hypogaea, L. aphaca, M. lupulina, P. pinnata). The larger polar/equatorial (P/E) ratio was found in T. alexandrinum (2.26 μm) and the smallest was found in M. lupulina (1.21 μm). The exine of T. resupinatum was 3.00 μm in thickness while others posses smaller exine thickness. The larger pore diameter was found in P. pinnata (16.01 μm) while others have smaller. The length of colpi was larger in Arachis hypogaea (32.24) while others posses smaller. Eight types of surface ornamentation (Psilate, faintly rugulate). Perforate and rugulate to verrucate have been observed under SEM. The pollens were europalynous type. Pollen morphology proved to be useful for the specific delimitation and serve as a tool for the identification and classification of taxa at specific and generic levels and can also be used as a key for the taxonomic features. Diversity in exine sculpture is helpful indicative characters for the isolation of closely related species. Hence, it is clear that both qualitative and quantitative characters of pollen can be useful for differentiating between taxa at specific level.

Assessment of the Crop Water Stress Index and Color Quality of Bur Clover (Medicago polymorpha L.) Under Different Irrigation Regimes

ABSTRACTRelationship between canopy temperature and soil moisture is important for using the potential of canopy temperature as an indicator of crop water stress. A two-year field experiment was carried out during June to September 2016 and 2017 at the Research Station of College of Agriculture, Darab, Shiraz University, Iran, to determine crop water stress index (CWSI) for bur clover. Irrigation regimes including well-watered [Irrigation according to 100% field capacity (FC)], mild water stress (75% FC), severe water stress (50% FC), and most severe water stress (25% FC) were arranged in a randomized complete block design with four replications. In 2016, CWSI values showed an increasing trend from June (0.066 in well-watered) to August (0.821 in most severe water stress) as a result of higher vapor pressure deficit (VPD) and depression in canopy-air temperature differences (Tc-Ta). A similar trend was observed in the second year. In both years, by increase in mean temperature from June to August, Tc-Ta differential increased and the highest monthly average value of CWSI for all treatments was obtained in August. By enhancing water stress, the color grading score decreased sharply (from 6 to 3) and stayed constant (2) for August and September. Also, a negative relationship was observed between CWSI and dry matter production (R2 = 0.88**) and color quality (R2 = 0.94**). It was concluded that mild water stress (75% FC) with mean seasonal CWSI being ranged about 0.198 to 0.294, without any loss in visual color quality might be the best irrigation regime for bur clover production.

Tolerance and recovery of the annual pasture legumes Melilotus siculus, Trifolium michelianum and Medicago polymorpha to soil salinity, soil waterlogging and the combination of these stresses

This study evaluated the responses to and recovery from soil waterlogging, soil salinity and the combination of these stresses of the annual pasture legumes Melilotus siculus cv. Neptune, Trifolium michelianum cv. Frontier and Medicago polymorpha cv. Scimitar. The major aim was to test the tolerance of these plants to salinity and waterlogging in soil inoculated with rhizobia, adding to previous controlled-environment studies, which have used nutrient solution cultures, as well as to examine post-stress recovery. Plants were grown in pots of soil inoculated with their appropriate species-specific rhizobia. Drained non-saline controls, and waterlogged non-saline, drained saline (100 mM NaCl) and waterlogged saline treatments were imposed for 3 weeks, followed by a 4 week recovery period. In the waterlogged saline soil, shoot dry mass of M. siculus was 63% of the control, compared to 10% for T. michelianum and 5% for M. polymorpha, and after the recovery phase was 75% of the control for M. siculus, 58% for T. michelianum and 4% for M. polymorpha. Foliar Na+ concentrations of T. michelianum and M. polymorpha were 2.8-fold higher than for M. siculus. The greater tolerance of M. siculus can be attributed to regulation of leaf Na+ concentrations in saline conditions and the formation of aerenchymatous phellem to enhance O2 supply to roots in waterlogged soils. This controlled glasshouse study using pots of soil supports earlier nutrient solution experiments and field observations that M. siculus possesses greater tolerance of combined waterlogging and salinity, than T. michelianum and M. polymorpha.

Rapid evolution of Medicago polymorpha during invasion shifts interactions with the soybean looper.

The Enemy Release Hypothesis posits that invasion of novel habitats can be facilitated by the absence of coevolved herbivores. However, a new environment and interactions with unfamiliar herbivores may impose selection on invading plants for traits that reduce their attractiveness to herbivores or for enhanced defenses compared to native host plants, leading to a pattern similar to enemy release but driven by evolutionary change rather than ecological differences. The Shifting Defense Hypothesis posits that plants in novel habitats will shift from specialized defense mechanisms to defense mechanisms effective against generalist herbivores in the new range. We tested these ideas by comparing herbivore preference and performance of native (Eurasia)‐ and invasive (New World)‐range Medicago polymorpha, using a generalist herbivore, the soybean looper, that co‐occurs with M. polymorpha in its New World invaded range. We found that soybean loopers varied in preference and performance depending on host genotype and that overall the herbivore preferred to consume plant genotypes from naïve populations from Eurasia. This potentially suggests that range expansion of M. polymorpha into the New World has led to rapid evolution of a variety of traits that have helped multiple populations become established, including those that may allow invasive populations to resist herbivory. Thus, enemy release in a novel range can occur through rapid evolution by the plant during invasion, as predicted by the Shifting Defense Hypothesis, rather than via historical divergence.

Efficacy of some Herbicides and Agricultural Practices on the Productivity of Sugar Beet (Beta vulgaris L.)

Two field experiments were conducted on sugar beet crop (Beta vulgaris) to increase the quality of yield in sugar beet by applying mixtures of pre- and post-emergence herbicides and non-chemical strategies. Triflusulfuron-methyl, phenemedipham7.5+ desmedipham 1.5+ ethofumesate 11.5, S-metolachlor, propaquizafop, and clethodim, in addition, Triflusulfuron-methyl +hand hoeing, phenmedipham 7.5+ desmedipham 1.5+ ethofumesate 11.5 +hand hoeing, first hand hoeing, second hand hoeing and untreated check were evaluated. All combinations were repeated twice. Percentage of weed reduction, total of all weeds, yield, yield components, percentages of total soluble solids (TSS), total yield of sugar beet ton per feddan and the percentages of weed density were calculated. Results revealed that, triflusulfuron-methyl + hand hoeing followed by phenmedipham7.5+ desmedipham 1.5+ ethofumesate 11.5+ hand hoeing and twice hand hoeing recorded equally the same effect followed by triflusulfuron-methyl followed by first hand hoeing when compared with untreated check. The reduction (weed control) percentages were 98, 96, 96, 84 and 81, respectively compared with untreated (check) in the first season. However, in the second season, the reduction percentages were 98, 96, 96, 86 and 80, respectively. The highest value of fresh weight andthe most two abundant species weeds were Beta vulgaris and Medicago hispida. Also, the results revealed that, there were significant effects between weed control treatments on crop yield (ton/fed) and untreated check during the two seasons, where the lowest yield was 9.38 ton/fed. while, the highest yield was 32.2 ton/fed. in the twice hand hoeing treatment. On the other hand, the effect of tested herbicides on fresh weight of grassy weeds (g/m2) in two seasons, in the first season, twice hand hoeing was found to be more effective followed by clethodim, propaquizafop and then S-metolachlor, where the percentages of reduction were 99, 93, 86 and 85, respectively compared with untreated check. However, in the second season, the reduction percentages were 100, 98, 95 and 95, respectively. The highest value of fresh weight andthe most abundant weed wasPhalaris sp. Also, the results showed significant effects between weed control treatments on crop yield (ton/fed), during the first season with low crop yield (2.22 ton/fed.) in untreated check and the high crop yield (33.525 ton/fed.) in propaquizafop treatment. The highest value of crop yield was 24 ton/fed. in twice hand hoeing and the lowest was 9.3 ton/fed. in untreated check in the second season. In two seasons, data showed that weed control treatments increased the tested yield parameters as a following: triflusulfuron-methyl +hand hoeing > phenmedipham 7.5+ desmedipham 1.5+ ethofumesate 11.5 > twice hand hoeing > first hand hoeing and Pop-S. In addition, the data showed that clethodim was found to be the most effective in weed control, highest value of yield component followed by S-metolachlor, propaquizafop and then twice hand hoeing. However, clethodim was the most effective in weed control with the highest value of yield components wheras twice hand hoeing was the lowest one. It can be concluded that, triflusulfuron-methyl +hand hoeing was highly effective in weed control with highest value of yield components, while hand hoeing is the lowest one.

The Phytol-rich Essential Oil from Fresh Medicago hispida Exerts Significant Inhibitory Activity against Escherichia coli

Medicago hispida is one of the most widely distributed and commonly cultivated plants of the genus Medicago in China. It is mainly consumed as a vegetable. In this paper, the extraction, chemical composition and antimicrobial potential of the essential oil from fresh M. hispida (EOFMH) were conducted and evaluated for the first time. The extraction yield of EOFMH was found to be 0.27% and 27 compounds were identified in EOFMH by gas chromatography-mass spectrometer (GC-MS) with the highest level of phytol, accounting for 48.8%. EOFMH exhibited certain inhibitory effects against Staphylococcus aureus, Escherichia coli, Candida albicans, Bacillus pumilus and Bacillus subtilis, particularly its antibacterial activity against E. coli was equivalent to that of chloramphenicol. Results obtained from present work provided strong evidence that EOFMH could be considered as a phytol-rich natural product and a new source of nature-based antibacterial agent to be applied in industry.

Metabolite profiling of Huaiyang Medicago polymorpha with different mowing crops

The main purpose of our study was to identify and compare secondary metabolites due to different mowing in order to make better use of Huaiyang Medicago polymorpha. The metabolite profiling of Huaiyang Medicago polymorpha with two mowing crops was performed using a rapid resolution liquid chromatography system with quadrupole time-of-flight mass spectrometer (RRLC-QTOFMS) followed by multivariate statistical analyses. Principal Component Analysis (PCA) results showed a clear distinction between two mowing crops. The major metabolites that contributed to mowing discrimination were identified. The results also showed that the content of major active compounds in Medicago polymorpha from the second crop are higher significantly than the first crop. This study suggests that the strategy is a reliable and simple method for the rapid discrimination of subtle variations due to different mowing crops.

Discovery of Three New Phytotoxins from the Fungus Aspergillus nidulans by Pathway Inactivation.

Fungi are a source of novel phytotoxic compounds to be explored in the search for effective and environmentally safe herbicides. The genetic inactivation of the biosynthetic pathway of the new phytotoxin cichorine has led to the isolation of three novel phytotoxins from the fungus Aspergillus nidulans: 8-methoxycichorine (4), 8-epi-methoxycichorine (5), and N-(4’-carboxybutyl) cichorine (6). The structure of the new compounds was clearly determined by a combination of nuclear magnetic resonance (NMR) analysis and high-resolution electrospray ionization (HRESIMS). The phytotoxic bioassay was studied on leaves from Zea mays and Medicago polymorpha L. at the concentration of 5 × 10−3 M by using a moist chamber technique. Novel phytotoxins 8-methoxycichorine (4), 8-epi-methoxycichorine (5), and N-(4’-carboxybutyl) cichorine (6) exhibited a better phytotoxic effect than cichorine.

A high-throughput method of analyzing multiple plant defensive compounds in minimized sample mass.

Premise of the StudyCurrent methods for quantifying herbivore‐induced alterations in plant biochemistry are often unusable by researchers due to practical constraints. We present a cost‐effective, high‐throughput protocol to quantify multiple biochemical responses from small plant tissue samples using spectrophotometric techniques.Methods and ResultsUsing Solanum lycopersicum and Medicago polymorpha leaves pre‐ and post‐herbivory, we demonstrate that our protocol quantifies common plant defense responses: peroxidase production, polyphenol oxidase production, reactive oxygen species production, total protein production, and trypsin‐like protease inhibition activity.ConclusionsCurrent protocols can require 500 mg of tissue, but our assays detect activity in less than 10 mg. Our protocol takes two people 6 h to run any of the assays on 300 samples in triplicate, or all of the assays on 20 samples. Our protocol enables researchers to plan complex experiments that compare local versus systemic plant responses, quantify environmental and genetic variation, and measure population‐level variation.

Rapid establishment of a flowering cline in Medicago polymorpha after invasion of North America.

To establish and spread in a new location, an invasive species must be able to carry out its life cycle in novel environmental conditions. A key trait underlying fitness is the shift from vegetative to reproductive growth through floral development. In this study, we used a common garden experiment and genotyping-by-sequencing to test whether the latitudinal flowering cline of the North American invasive plant Medicago polymorpha was translocated from its European native range through multiple introductions, or whether the cline rapidly established due to evolution following a genetic bottleneck. Analysis of flowering time in 736 common garden plants showed a latitudinal flowering time cline in both the native and invaded ranges where genotypes from lower latitudes flowered earlier. Genotyping-by-sequencing of 9,658 SNPs in 446 individuals revealed two major subpopulations of M.polymorpha in the native range, only one of which is present in the invaded range. Additionally, native range populations have higher genetic diversity than invaded range populations, suggesting that a genetic bottleneck occurred during invasion. All invaded range individuals are closely related to plants collected from native range populations in Portugal and southern Spain, and population assignment tests assigned invaded range individuals to this same narrow source region. Taken together, our results suggest that latitudinal clinal variation in flowering time has rapidly evolved across the invaded range despite a genetic bottleneck following introduction.