Influence of physico-chemical traits of bitter gourd, Momordica charantia L. on larval density and resistance to melon fruit fly, Bactrocera cucurbitae (Coquillett)

Abstract:  Melon fruit fly, Bactrocera cucurbitae (Coquillett) is one of the most important pests of bitter gourd, Momordica charantia L. Because of the difficulties associated with chemical control of this pest, it is important to identify the traits associated with resistance and their influence on pest multiplication. There were significant differences in test genotypes for fruit infestation and larval density/fruit. The wild accessions, IC 256185, IC 248256, IC 213311, IC 248282, IC 256110 and IC 248281 were identified as resistance sources to melon fruit fly. There was a significant and positive correlation ( r  = 0.96) between percentage fruit infestation and larval density/fruit. Percentage fruit infestation and larval density/fruit were positively correlated with depth of ribs, flesh thickness, fruit diameter and fruit length, and negatively associated with fruit toughness. Flesh thickness and fruit diameter explained 93.0% of the total variation for fruit fly infestation, and flesh thickness and fruit length explained 76.3% of the variation for larval density/fruit. Ascorbic acid, nitrogen, phosphorus, potassium, protein, reducing sugars, non-reducing sugars and total sugars were negatively correlated, while the moisture content showed a positive association with fruit fly infestation and larval density/fruit. Moisture, potassium and reducing sugar content explained 97.4% of the total variation in fruit infestation, while moisture, phosphorus, protein, reducing and total sugars explained 85.7% variation for larval density/fruit.     

Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinis

The roots of date palm contain four cell wall‐bound phenolic acids identified as p‐hydroxybenzoic, p‐coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2–55.8% of cell wall‐bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre‐infection contents of p‐coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p‐hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre‐infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall‐bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post‐infection contents of cell wall‐bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p‐hydroxybenzoic acid (1.54 μmol/g), p‐coumaric acid (2.77 μmol/g) and ferulic acid (2.64 μmol/g) and on the fifteenth day for sinapic acid (1.85 μmol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p‐hydroxybenzoic acid, 2.6 times for p‐coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p‐coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre‐infection contents of the resistant cultivar. The contents of p‐hydroxybenzoic acid in the susceptible cultivar roots did not present post‐infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall‐bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection.     

Fluctuations in fruit fly abundance and infestation in sweet gourd fields in relation to varied meteorological factors

The study was conducted with the aim of furthering our understanding of seasonality in the population dynamics and infestation rates of the fruit fly Bactrocera spp. in sweet gourd (Cucurbita moschata) during winter and summer in 2017. We also investigated the effects of using methyl eugenol traps on fly abundance and infestation. Two fruit fly species, namely, B. cucurbitae and B. dorsalis, were present in the sweet gourd field, and we observed fluctuations in their abundance. Compared to B. dorsalis, B. cucurbitae was significantly more abundant in both winter and summer. Infestation level was found to be the highest in fields lacking methyl eugenol traps in both seasons. Fruit fly larval population per infested fruit was higher in summer than in winter. Fly abundance was significantly and positively correlated with mean temperature and rainfall but significantly and negatively correlated with light intensity. Relative humidity was insignificantly but positively correlated with fly abundance. The temperature, light intensity, relative humidity, and rainfall individually explained 48.9, 24.1, 0.8, and 1.6% of variation in fruit fly abundance, respectively. The combined effect of the weather parameters on fruit fly abundance was 75.4% and was significant predictor of fruit fly abundance.     

RNAi‐suppression of barley caffeic acid O‐methyltransferase modifies lignin despite redundancy in the gene family

Caffeic acid O‐methyltransferase (COMT), the lignin biosynthesis gene modified in many brown‐midrib high‐digestibility mutants of maize and sorghum, was targeted for downregulation in the small grain temperate cereal, barley (Hordeum vulgare), to improve straw properties. Phylogenetic and expression analyses identified the barley COMT orthologue(s) expressed in stems, defining a larger gene family than in brachypodium or rice with three COMT genes expressed in lignifying tissues. RNAi significantly reduced stem COMT protein and enzyme activity, and modestly reduced stem lignin content while dramatically changing lignin structure. Lignin syringyl‐to‐guaiacyl ratio was reduced by ~50%, the 5‐hydroxyguaiacyl (5‐OH‐G) unit incorporated into lignin at 10‐–15‐fold higher levels than normal, and the amount of p‐coumaric acid ester‐linked to cell walls was reduced by ~50%. No brown‐midrib phenotype was observed in any RNAi line despite significant COMT suppression and altered lignin. The novel COMT gene family structure in barley highlights the dynamic nature of grass genomes. Redundancy in barley COMTs may explain the absence of brown‐midrib mutants in barley and wheat. The barley COMT RNAi lines nevertheless have the potential to be exploited for bioenergy applications and as animal feed.     

Wine phenolic compounds influence the production of volatile phenols by wine-related lactic acid bacteria

Aims: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4‐vinylphenol [4VP] and 4‐ethylphenol [4EP]) from the metabolism of p‐coumaric acid by lactic acid bacteria (LAB). Methods and Results: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p‐coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p‐coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l^?1) of tannins inhibited the synthesis of 4VP by Lact. plantarum. Conclusions: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p‐coumaric acid. On the other hand, tannins exert an inhibitory effect. Significance and Impact of the Study: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.     

Metabolomics reveals herbivore‐induced metabolites of resistance and susceptibility in maize leaves and roots

Plants respond to herbivory by reprogramming their metabolism. Most research in this context has focused on locally induced compounds that function as toxins or feeding deterrents. We developed an ultra‐high‐pressure liquid chromatography time‐of‐flight mass spectrometry (UHPLC‐TOF‐MS)‐based metabolomics approach to evaluate local and systemic herbivore‐induced changes in maize leaves, sap, roots and root exudates without any prior assumptions about their function. Thirty‐two differentially regulated compounds were identified from Spodoptera littoralis‐infested maize seedlings and isolated for structure assignment by microflow nuclear magnetic resonance (CapNMR). Nine compounds were quantified by a high throughput direct nano‐infusion tandem mass spectrometry/mass spectrometry (MS/MS) method. Leaf infestation led to a marked local increase of 1,3‐benzoxazin‐4‐ones, phospholipids, N‐hydroxycinnamoyltyramines, azealic acid and tryptophan. Only few changes were found in the root metabolome, but 1,3‐benzoxazin‐4‐ones increased in the vascular sap and root exudates. The role of N‐hydroxycinnamoyltyramines in plant–herbivore interactions is unknown, and we therefore tested the effect of the dominating p‐coumaroyltyramine on S. littoralis. Unexpectedly, p‐coumaroyltyramine was metabolized by the larvae and increased larval growth, possibly by providing additional nitrogen to the insect. Taken together, this study illustrates that herbivore attack leads to the induction of metabolites that can have contrasting effects on herbivore resistance in the leaves and roots.     

Production of Substituted Styrene Bioproducts from Lignin and Lignocellulose Using Engineered Pseudomonas putida KT2440

Ferulic acid is a renewable chemical found in lignocellulose from grasses such as wheat straw and sugarcane. Pseudomonas putida is able to liberate and metabolize ferulic acid from plant biomass. Deletion of the hydroxycinnamoyl‐CoA hydratase‐lyase gene (ech) produced a strain of P. putida unable to utilize ferulic and p‐coumaric acid, which is able to accumulate ferulic acid and p‐coumaric acid from wheat straw or sugar cane bagasse. Further engineering of this strain saw the replacement of ech with the phenolic acid decarboxylase padC, which converts p‐coumaric and ferulic acid into 4‐vinylphenol and the flavor agent 4‐vinylguaiacol, respectively. The engineered strain containing padC is able to generate 4‐vinylguaiacol and 4‐vinylphenol from media containing lignocellulose or Green Value Protobind lignin as feedstock, and does not require the addition of an exogenous inducer molecule. Biopolymerization of 4‐vinylguaiacol and 4‐vinylcatechol styrene products is also carried out, using Trametes versicolor laccase, to generate “biopolystyrene” materials on small scale.     

Genome‐wide identification of tolerance mechanisms toward p‐coumaric acid in Pseudomonas putida

The soil bacterium Pseudomonas putida KT2440 has gained increasing biotechnological interest due to its ability to tolerate different types of stress. Here, the tolerance of P. putida KT2440 toward eleven toxic chemical compounds was investigated. P. putida was found to be significantly more tolerant toward three of the eleven compounds when compared to Escherichia coli. Increased tolerance was for example found toward p‐coumaric acid, an interesting precursor for polymerization with a significant industrial relevance. The tolerance mechanism was therefore investigated using the genome‐wide approach, Tn‐seq. Libraries containing a large number of miniTn5‐Km transposon insertion mutants were grown in the presence and absence of p‐coumaric acid, and the enrichment or depletion of mutants was quantified by high‐throughput sequencing. Several genes, including the ABC transporter Ttg2ABC and the cytochrome c maturation system (ccm), were identified to play an important role in the tolerance toward p‐coumaric acid of this bacterium. Most of the identified genes were involved in membrane stability, suggesting that tolerance toward p‐coumaric acid is related to transport and membrane integrity.

     

Interaction of acid exudates in chickpea with biological activity of Bacillus thuringiensis towards Helicoverpa armigera

The gram pod borer, Helicoverpa armigera, is one of the most important constraints to chickpea production. High acidity of chickpea exudates is associated with resistance to pod borer, H. armigera; however, acidic exudates in chickpea might influence the biological activity of the bacterium, Bacillus thuringiensis (Bt), applied as a foliar spray or deployed in transgenic plants for controlling H. armigera. Therefore, studies were undertaken to evaluate the biological activity of Bt towards H. armigera on chickpea genotypes with different amounts of organic acids. Significantly lower leaf feeding, larval survival and larval weights were observed on ICC 506EB, followed by C 235, and ICCV 10 across Bt concentrations. Leaf feeding by the larvae and larval survival and weights decreased with an increase in Bt concentration. However, rate of decrease in leaf feeding and larval survival and weights with an increase in Bt concentration was greater on L 550 and ICCV 10 than on the resistant check, ICC 506EB, suggesting that factors in the resistant genotypes, particularly the acid exudates, resulted in lower levels of biological activity of Bt possibly because of antifeedant effects of the acid exudates. Antifeedant effects of acid exudates reduced food consumption and hence might reduce the efficacy of Bt sprays on insect‐resistant chickpea genotypes or Bt‐transgenic chickpeas, although the combined effect of plant resistance based on organic acids, and Bt had a greater effect on survival and development of H. armigera than Bt alone.     

Variability in the production of amylase by three isolates ofMyrothecium roridum

Amylase production by three isolates ofMyrothecium roridum under different cultural conditions was studied. Starch followed by dextrin induced maximum amylase production (dextrinizing and saccharifying) by all the three isolates. Glucose was a poor substrate for the production of amylases. Bitter gourd isolate was a comparatively more efficient producer of amylases than the other two isolates. Addition of glucose to the starch medium resulted in a repression of amylases. Urea was a good source of nitrogen for induction of dextrinizing amylase in bitter gourd and pearl millet isolates.l-Asparagine,l-tyrosine were good sources of nitrogen for induction of saccharifying amylase in bitter gourd, water melon and pearl millet isolate, respectively. With a few exceptions, dextrinizing amylase production was inhibited by gibberellic acid, cycocel, calcium chloride and calcium sulfate, while these substances stimulated saccharifying-amylase production. No correlation could be observed between amylase production and vegetative growth. Amylases of all the three isolates ofM. roridum were characterized.     

Tolerance as a mechanism of resistance to Thrips palmi in common beans

Tolerance as a mechanism of resistance to the melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), in common beans, Phaseolus vulgaris L., was evaluated under field and greenhouse conditions. Seven resistant (Brunca, BH‐5, BH‐60, BH‐130, BH‐144, EMP 486, and FEB 115) and five susceptible (PVA 773, EMP 514, BAT 477, APN 18, and RAZ 136) bean genotypes were assessed according to adult and larval populations, visual damage and reproductive adaptation scores, and yield components in field trials. From these genotypes, four resistant (Brunca, BH‐130, EMP 486, and FEB 115) and two susceptible (APN 18 and RAZ 136) genotypes were selected for quantification of proportional plant weight and height increase changes due to thrips infestation in greenhouse tests. Under medium to high thrips infestation in the field, most resistant genotypes tended to have higher reproductive adaptation and lower yield losses, though they did not always suffer less damage, as compared to susceptible genotypes. In the greenhouse, resistant genotypes showed less reduction in plant dry weight and height increase than did some susceptible ones under the same infestation pressure. Results from both field trials and greenhouse tests suggest the possible expression of tolerance as a mechanism of resistance to T. palmi in the resistant genotype EMP 486, and confirm the existence of antixenosis in FEB 115, whereas tolerance might be combined with other resistance mechanisms in Brunca.     

南美斑潜蝇幼虫为害对黄瓜叶片中水杨酸和茉莉酸的诱导作用

【目的】为揭示南美斑潜蝇Liriomyza huidobrensis (Blanchard)与其寄主相互作用的机理, 为利用诱导抗性控制南美斑潜蝇的发生为害奠定必要的基础。【方法】本文采用高效液相色谱法（HPLC）和超高效液相色谱法-质谱联用法（UPLC MS）, 分别测定了南美斑潜蝇幼虫为害对黄瓜叶片中茉莉酸（jasmonic acid, JA）和水杨酸（salicylic acid, SA）的诱导作用。【结果】南美斑潜蝇幼虫持续为害1 d后, 受害黄瓜叶片内JA含量即显著高于健康对照, 轻度受害处理和重度受害处理分别在第3天和第5天上升幅度最大, 分别比健康对照增加2.01倍和1.62倍; 而SA含量在3 d后才显著高于健康对照, 轻度受害处理和重度受害处理在第9天上升幅度最大, 分别比健康对照增加4.66倍和1.67倍; 轻度受害对JA和SA的系统诱导作用不明显, 而重度受害对JA和SA具有明显的系统诱导作用。【结论】南美斑潜蝇幼虫为害对黄瓜叶片内JA和SA具有诱导作用。     

Age‐stage,two‐sex life tables of Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) with a discussion on the problem of applying female age‐specific life tables to insect populations

Abstract Age‐stage, two‐sex life tables of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), reared on cucumber (Cucumis sativus L.), sponge gourd (Luffa cylindrica Roem) and a carrot medium (mashed Daucus carota L. mixed with sucrose and yeast hydrolysate) were constructed under laboratory conditions at 25 ± 1°C, 65%± 0.5% relative humidity, and a photoperiod 12 : 12 h (L : D). The intrinsic rates of increase of B. cucurbitae were 0.144 6, 0.141 2 and 0.068 8 days on cucumber, sponge gourd, and carrot medium, respectively. The highest net reproduction rate was 172 offspring per fly reared on sponge gourd. The mean generation times of B. cucurbitae ranged from 34 days reared on cucumber to 56 days reared on carrot medium. The life history raw data was analyzed using the traditional female age‐specific life table and compared to results obtained using the age‐stage, two‐sex life table. When the age‐specific female life table is applied to an age‐stage‐structured two‐sex population, survival and fecundity curves will be improperly manipulated due to an inability to include variation in preadult development time. We discussed different interpretations of the relationship between the net reproductive rate and the intrinsic rate of increase to clarify possible misunderstanding in the literature.     

Eradication of the melon fly,Dacus cucurbitae,from Kume is., Okinawa with the sterile insect release method

The sterile insect release method was applied to eradicate the melon fly, Dacus cucurbitae, from the 58.5 km² island of Kume, in the Okinawa Islands group. Weekly releases of 1 to 1.5 million flies irradiated as pupae with 6–7 kR from a cobalt-60 source did not decrease the wild melon fly population. Releases of 1.5–2 million pupae per week made from September, 1975 to January, 1976 decreased the percent egg-hatch of females caught on Kume Is., but did not decrease the percent infestation significantly. The number of pupae released was increased from February, 1976 to accelerate the eradication process. When the number of pupae released exceeded 3.5 million per week, a rapid increase in the ratio of marked (sterile) to unmarked (wild) flies, a remarkable decrease in percent egg-hatch, and a decrease in percent infestation of fruits were observed. There has been no sign of melon fly infestation in wild cucurbit fruits from October, 1976 to the present time (April, 1977), despite the fact that more than 70,000 fruits were carefully examined. The eradication of the melon fly from Kume Is. was thus achieved by April, 1977, after the release of 264 million sterile fly pupae.     

Characterization of Miscanthus cell wall polymers

Efficient utilization of lignocellulosic Miscanthus biomass for the production of biochemicals, such as ethanol, is challenging due to its recalcitrance, which is influenced by the individual plant cell wall polymers and their interactions. Lignocellulosic biomass composition differs depending on several factors, such as plant age, harvest date, organ type, and genotype. Here, four selected Miscanthus genotypes (Miscanthus sinensis, Miscanthus sacchariflorus, Miscanthus × giganteus, Miscanthus sinensis × Miscanthus sacchariflorus hybrid) were grown and harvested, separated into stems and leaves, and characterized for their non‐starch polysaccharide composition and structures, lignin contents and structures, and hydroxycinnamate profiles (monomers and ferulic acid dehydrodimers). Polysaccharides of all genotypes are mainly composed of cellulose and low‐substituted arabinoxylans. Ratios of hemicelluloses to cellulose were comparable, with the exception of Miscanthus sinensis that showed a higher hemicellulose/cellulose ratio. Lignin contents of Miscanthus stems were higher than those of Miscanthus leaves. Considering the same organs, the four genotypes did not differ in their Klason lignin contents, but Miscanthus × giganteus showed the highest acetylbromide soluble lignin content. Lignin polymers isolated from stems varied in their S/G ratios and linkage type distributions across genotypes. p‐Coumaric acid was the most abundant ester‐bound hydroxycinnamte monomer in all samples. Ferulic acid dehydrodimers were analyzed as cell wall cross‐links, with 8‐5‐coupled diferulic acid being the main dimer, followed by 8‐O‐4‐, and 5‐5‐diferulic acid. Contents of p‐coumaric acid, ferulic acid, and ferulic acid dimers varied depending on genotype and organ type. The largest amount of cell wall cross‐links was analyzed for Miscanthus sinensis.     

The bottle gourd genome provides insights into Cucurbitaceae evolution and facilitates mapping of a Papaya ring‐spot virus resistance locus

Bottle gourd (Lagenaria siceraria) is an important vegetable crop as well as a rootstock for other cucurbit crops. In this study, we report a high‐quality 313.4‐Mb genome sequence of a bottle gourd inbred line, USVL1VR‐Ls, with a scaffold N50 of 8.7 Mb and the longest of 19.0 Mb. About 98.3% of the assembled scaffolds are anchored to the 11 pseudomolecules. Our comparative genomic analysis identifies chromosome‐level syntenic relationships between bottle gourd and other cucurbits, as well as lineage‐specific gene family expansions in bottle gourd. We reconstructed the genome of the most recent common ancestor of Cucurbitaceae, which revealed that the ancestral Cucurbitaceae karyotypes consisted of 12 protochromosomes with 18 534 protogenes. The 12 protochromosomes are largely retained in the modern melon genome, while have undergone different degrees of shuffling events in other investigated cucurbit genomes. The 11 bottle gourd chromosomes derive from the ancestral Cucurbitaceae karyotypes followed by 19 chromosomal fissions and 20 fusions. The bottle gourd genome sequence has facilitated the mapping of a dominant monogenic locus, Prs, conferring Papaya ring‐spot virus (PRSV) resistance in bottle gourd, to a 317.8‐kb region on chromosome 1. We have developed a cleaved amplified polymorphic sequence (CAPS) marker tightly linked to the Prs locus and demonstrated its potential application in marker‐assisted selection of PRSV resistance in bottle gourd. This study provides insights into the paleohistory of Cucurbitaceae genome evolution, and the high‐quality genome sequence of bottle gourd provides a useful resource for plant comparative genomics studies and cucurbit improvement.     

CEPA处理对苦瓜采后呼吸、乙烯释放及保护系统的影响

CEPA处理适期采收的食用苦瓜后,使其呼吸速率,乙烯释放速率明显增加,呼吸上升、瓜皮转黄期由采后第8天提前至第6天,且使贮期缩短4d。CEPA处理不同程度地抑制了苦瓜采后前期的各种保护酶活性,且使衰老后期的保护酶活性上升期提前。CEPA处理后前6d,AsA、GSH含量均呈上升趋势;6d后迅速下降,且下降速率大于CK。CEPA处理未改变苦瓜采后MDA含量总体下降的趋势。     

PHYSIOLOGICAL EFFECTS OF RESVERATROL AND COUMARIC ACID ON TWO MAJOR GROUNDNUT PESTS AND THEIR EGG PARASITOID BEHAVIOR

Groundnut, Arachis hypogea L., is one of the plant species that synthesizes phenolic compounds, resveratrol and coumaric acid. They are induced as a defense strategy in plant in response to feeding lepidopterans. The present study investigated the role of resveratrol and coumaric acid in producing antiherbivore effects as a direct defense against two major groundnut pests, Spodoptera litura F. and Amsacta albistriga W., and in indirect defense by attracting the egg parasitoid Trichogramma chilonis Ishii under laboratory conditions. The phenolic compounds deterred the feeding of both pests and caused reduction in the larval weights in a dose‐dependent manner in leaf disk bioassays. Antioxidant mechanisms of larvae fed with these phenols were measured by estimating the activities of superoxide dismutase (SOD), ascorbate peroxidase (APOX), and catalase (CAT). Enzyme activities increased significantly in experimental larvae, more so in resveratrol‐treated than in coumaric acid treated larvae. Feeding larvae with resveratrol and coumaric acid resulted in enhanced activities of detoxifying enzymes, carboxyl esterase (EST), and glutathione‐S‐transferase (GST) in the midgut tissues of both species, indicating the toxic nature of these compounds. Trichogramma chilonis was more attracted toward coumaric acid treatments in Y‐olfactometer tests than to resveratrol. This study contributes to the understanding of the roles of resveratrol and coumaric acid in direct as well as indirect defense, we infer a possible utilization of these compounds in alternate measures of groundnut pest control in future.     

Chemical Characterization and Phytotoxic Effects of the Aerial Parts of Ruzigrass (Urochloa ruziziensis)

Studies of the phytotoxic effects between plants can be a crucial tool in the discovery of innovative compounds with herbicide potential. In this sense, we can highlight ruzigrass (Urochloa ruziziensis), which is traditionally used in the crop rotation system in order to reduce weed emergence. The aim of this work was to characterize the secondary metabolites of ruzigrass and to evaluate its phytotoxic effects. In total, eight compounds were isolated: friedelin, oleanolic acid, α‐amyrin, 1‐dehydrodiosgenone, sitosterol and stigmasterol glycosides, tricin and p‐coumaric acid. Phytotoxic effects of the crude methanolic extract and fractions of ruzigrass were assessed using germination rate, initial seedling growth, and biomass of Bidens pilosa, Euphorbia heterophylla and Ipomoea grandifolia. Chemometric analysis discriminated the weed species into three groups, and B. pilosa was the most affected by fractions of ruzigrass. The phytotoxic activities of 1‐dehydrodiosgenone, tricin, and p‐coumaric acid are also reported, and p‐coumaric acid and 1‐dehydrodiosgenone were active against B. pilosa.     

Ferulic acid: a key component in grass lignocellulose recalcitrance to hydrolysis

In the near future, grasses must provide most of the biomass for the production of renewable fuels. However, grass cell walls are characterized by a large quantity of hydroxycinnamic acids such as ferulic and p‐coumaric acids, which are thought to reduce the biomass saccharification. Ferulic acid (FA) binds to lignin, polysaccharides and structural proteins of grass cell walls cross‐linking these components. A controlled reduction of FA level or of FA cross‐linkages in plants of industrial interest can improve the production of cellulosic ethanol. Here, we review the biosynthesis and roles of FA in cell wall architecture and in grass biomass recalcitrance to enzyme hydrolysis.