Ecological and Industrial Implications of Dynamic Seaweed-Associated Microbiota Interactions

Seaweeds are broadly distributed and represent an important source of secondary metabolites (e.g., halogenated compounds, polyphenols) eliciting various pharmacological activities and playing a relevant ecological role in the anti-epibiosis. Importantly, host (as known as basibiont such as algae)–microbe (as known as epibiont such as bacteria) interaction (as known as halobiont) is a driving force for coevolution in the marine environment. Nevertheless, halobionts may be fundamental (harmless) or detrimental (harmful) to the functioning of the host. In addition to biotic factors, abiotic factors (e.g., pH, salinity, temperature, nutrients) regulate halobionts. Spatiotemporal and functional exploration of such dynamic interactions appear crucial. Indeed, environmental stress in a constantly changing ocean may disturb complex mutualistic relations, through mechanisms involving host chemical defense strategies (e.g., secretion of secondary metabolites and antifouling chemicals by quorum sensing). It is worth mentioning that many of bioactive compounds, such as terpenoids, previously attributed to macroalgae are in fact produced or metabolized by their associated microorganisms (e.g., bacteria, fungi, viruses, parasites). Eventually, recent metagenomics analyses suggest that microbes may have acquired seaweed associated genes because of increased seaweed in diets. This article retrospectively reviews pertinent studies on the spatiotemporal and functional seaweed-associated microbiota interactions which can lead to the production of bioactive compounds with high antifouling, theranostic, and biotechnological potential.     

Jasmonic and salicylic acid-induced resistance in sorghum against the stem borer Chilo partellus

Induced resistance was studied in three sorghum genotypes (IS2205, ICSV1 and ICSV700) against Chilo partellus (Swinhoe) (Lepidoptera; Pyralidae) infestation and jasmonic acid (JA) and salicylic acid (SA) application. The activity of plant defensive enzymes [peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD), and catalase (CAT)], and the amounts of total phenols, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and proteins were recorded at 6 days after infestation. The induction of enzyme activities and the amounts of secondary metabolites varied among the genotypes and treatments. The genotype IS2205 showed a stronger effect than that of ICSV1 or ICSV 700. Treatment with JA followed by insect infestation induced greater levels of enzymes and secondary metabolites. The results suggest that JA induces greater levels of resistance components in sorghum plants against insect pests. Thus, pretreatment of plants with elicitors including JA and SA could provide a greater opportunity for plant defense against herbivores.     

Food preferences and consumption parameters of Cabbage butterfly,Pieris brassicae (Lepidoptera: Pieridae) on different kale genotypes

Journal of Plant Diseases and Protection - Food preferences and consumption parameters of Pieris brassicae larvae were carried out on 17 kale (Brassica oleracea var. acephala) genotypes....     

Effect of plant secondary metabolites on legume pod borer, Helicoverpa armigera

The effect of various flavonoids, lectins and phenyl β-d-glucoside on larval survival, weights and the activities of digestive (total serine protease and trypsin) and detoxifying [esterase and glutathione-S-transferase] enzymes of Helicoverpa armigera larvae at 5 and 10 days after treatment (DAT) was studied through diet incorporation assay. Flavonoids (quercetin, cinnamic acid, caffeic acid, chlorogenic acid, catechin, trihydroxyflavone, gentisic acid, ferulic acid, protocatechuic acid and umbelliferone) were incorporated in artificial diet at 100, 500 and 1000 ppm, lectins: groundnut leaf lectin (GLL), concavalin (ConA) and phenyl β-d-glucoside at 2.5 and 5 μg mL^?1. Flavonoids such as chlorogenic acid, caffeic acid and protocatechuic acid at 1,000 ppm were more toxic to H. armigera larvae at 10 DAT than quercetin, catechin, cinnamic acid, trihydroxyflavone, gentisic acid, ferulic acid and umbelliferone. Larval growth and development were significantly reduced in H. armigera larvae fed on a diet with GLL and ConA at 5 μg mL^?1 compared to the larvae fed at 2.5 and 1.25 μg mL^?1 concentrations. The enzyme activities of the larvae were significantly reduced in flavonoid-treated diets. The flavonoids such as chlorogenic acid, caffeic acid, gentisic acid, trihydroxyflavone, catechin and protocatechuic acid, and lectins, GLL and ConA can be utilized in insect control programs.     

Effect of humic acid amendment on cadmium bioavailability and accumulation by pak choi (Brassica rapa ssp. chinensis L.) to alleviate dietary toxicity risk

Cadmium (Cd) contamination in soil and its movement into food chain through vegetable dietary poses a risk to human health. A pot experiment was conducted to investigate the effect of humic acid (HA) and two cultivars of Brassica rapa ssp. chinensis L. (pak choi) with differing Cd accumulation abilities on Cd accumulation in different Cd contaminated Ferralsol, Histosol and Luvisol soils. The results showed that HA significantly increased soil pH and cation exchange capacity in Ferralsol (acidic) and Histosol (neutral) soils. HA was more effective in Ferralsol and Histosol soil in reducing bioavailable Cd and its accumulation in both cultivars. Low and high Cd accumulating cultivars combined with HA effectively reduced shoot Cd concentration by 7–34% and 19–35% in Histosol soil, whereas 22–34% and 11–26% in Ferralsol soil, respectively. However, no such reduction was observed for Cd accumulation and bioavailability in Cd-contaminated Luvisol (alkaline) soil. Application of HA enhanced shoot dry biomass in both cultivars grown in Histosol and Ferralsol soils. Therefore, the HA amendment combination with low Cd accumulating cultivars of pak choi could be an effective method for phytostabilization and reduce health risks associated with consuming this vegetable grown in Cd-contaminated acidic and neutral pH soils.