Genetic mapping identifies a rice naringenin O-glucosyltransferase that influences insect resistance.

Naringenin, the biochemical precursor for predominant flavonoids in grasses, provides protection against UV damage, pathogen infection and insect feeding. To identify previously unknown loci influencing naringenin accumulation in rice (Oryza sativa), recombinant inbred lines derived from the Nipponbare and IR64 cultivars were used to map a quantitative trait locus (QTL) for naringenin abundance to a region of 50 genes on rice chromosome 7. Examination of candidate genes in the QTL confidence interval identified four predicted uridine diphosphate-dependent glucosyltransferases (Os07g31960, Os07g32010, Os07g32020 and Os07g32060). In vitro assays demonstrated that one of these genes, Os07g32020 (UGT707A3), encodes a glucosyltransferase that converts naringenin and uridine diphosphate-glucose to naringenin-7-O-ß-d-glucoside. The function of Os07g32020 was verified with CRISPR/Cas9 mutant lines, which accumulated more naringenin and less naringenin-7-O-ß-d-glucoside and apigenin-7-O-ß-d-glucoside than wild-type Nipponbare. Expression of Os12g13800, which encodes a naringenin 7-O-methyltransferase that produces sakuranetin, was elevated in the mutant lines after treatment with methyl jasmonate and insect pests, Spodoptera litura (cotton leafworm), Oxya hyla intricata (rice grasshopper) and Nilaparvata lugens (brown planthopper), leading to a higher accumulation of sakuranetin. Feeding damage from O. hyla intricata and N. lugens was reduced on the Os07g32020 mutant lines relative to Nipponbare. Modification of the Os07g32020 gene could be used to increase the production of naringenin and sakuranetin rice flavonoids in a more targeted manner. These findings may open up new opportunities for selective breeding of this important rice metabolic trait.

Shelf-life extension of Pacific white shrimp using algae extracts during refrigerated storage.

BACKGROUND: Shrimp is a low-fat, high-protein aquatic product, and is susceptible to spoilage during storage. To establish an effective method for the quality control of Pacific white shrimp, the effects of polyphenols (PP) and polysaccharides (PS) from Porphyra yezoensis on the quality of Pacific white shrimp were assessed during refrigerated storage. Pacific white shrimp samples were treated with 5 g L-1 polyphenols, and 8 g L-1 polysaccharides, then stored at 4 ± 1 °C for 8 days. All samples were subjected to measurement of total viable count (TVC), pH, total volatile basic nitrogen (TVB-N), K-value, thiobarbituric acid (TBA), polyphenol oxidase (PPO) activity, and were also assessed by sensory evaluation. RESULTS: The results showed that PP, PS, and the mixture of polyphenols and polysaccharides (PP+PS) could inhibit the increase of total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and K-value, and reduce total viable count (TVC) compared with the control group. PP could also inhibit polyphenol oxidase (PPO) activity. Sensory evaluation proved the efficacy of PP and PS by maintaining the overall quality of Pacific white shrimp during refrigerated storage. Moreover, PP+PS could extend the shelf-life of shrimp by 3-4 days compared with the control group. CONCLUSION: PP+PS could more effectively maintain quality and extend shelf-life during refrigerated storage. © 2016 Society of Chemical Industry.

Vermicomposting of Pleurotus eryngii spent mushroom substrates and the possible mechanisms of vermicompost suppressing nematode disease caused by Meloidogyne incognita.

The mushroom industry produces a large amount of spent mushroom substrate (SMS), which requires a large geographical footprint and causes pollution. Vermicomposting is a low-cost technology for its value in recycling of organic wastes and production of beneficial organic fertilizers. In this study, the changes of physicochemical properties was characterized during vermicomposting of Pleurotus eryngii SMS with cow dung (CD) as amendment. The efficiency and possible mechanisms of vermicompost suppressing disease induced by Meloidogyne incognita was also investigated. Six combinations with different ratios of SMS and cow dung (CD) was included in the vermicomposting using Eisenia fetida. Effect of vermicompost against disease induced by M. incognita on tobacco was conducted under greenhouse condition. And the possible mechanisms of vermicompost suppressing M. incognita was investigated by evaluated the species diversity of nematode-trapping fungi (NTF) in soil, and the defense response enzymes in tobacco. The combination of 65% SMS +35% CD was more suitable for vermicomposting, in which the highest vermicompost production (57%) and earthworm biomass increment (268%) were achieved. Additionally, the reduction in pH, total organic carbon, carbon: nitrogen ratio, and the pronounced elevation in four overall nutrient status were also observed. Soil amended with vermicompost (100:1 w/w) showed 61% control efficiency against nematode disease caused by M. incognita on tobacco, which significantly higher than that of the normal compost (24%). Comparing to the normal compost, the potential mechanism of vermicompost suppressing M. incognita could be rely on promoting species diversity of NTF in soil and enhancing the activities of the defense response enzymes in tobacco plant. Our findings indicate that vermicomposting is a promising technology for recycling of P. eryngii SMS, and the resulting vermicompost as organic fertilizer can be sued for management of the diseases caused by root-knot nematodes. This study establish a sustainable avenue for P. eryngii SMS disposal and a practical manner for controlling pathogens.

The Effect of the Co-Blending Process on the Sensing Characteristics of Conductive Chloroprene Rubber/Natural Rubber Composites.

Three different blending procedures were used to create multiwalled carbon nanotube (MWCNT)-modified chloroprene rubber (CR)/natural rubber (NR) blended composites (MWCNT/CR-NR). The effects of the blending process on the morphology of the conductive network and interfacial contacts were researched, as well as the resistance-strain response behavior of the composites and the mechanism of composite sensitivity change under different processes. The results show that MWCNT/CR-NR composites have a wide strain range (ε = 300%) and high dynamic resistance-strain response repeatability. Different blending procedures have different effects on the morphology of the conductive network and the interfacial interactions of the composites. If the blending procedures have wider conductive phase spacing and stronger interfacial contacts, the change in the conductive path and tunneling distance occurs more rapidly, and the material has a higher resistance-strain response sensitivity.

Identification of Xanthones from the Mangosteen Pericarp that Inhibit the Growth of Ralstonia solanacearum.

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive bacterial diseases in agriculture. There is no effective control method, although chemical pesticides are used to prevent this disease, but they may lead to serious problems of environmental pollution. Natural products from plants can be rich and environmentally friendly sources for a broad spectrum biological control of bacteria. This study focuses on the pericarp of mangosteen (Garcinia mangostana) using bioactivity-guided analysis of different fractions and liquid chromatography-mass spectrometry combined with multivariate analysis to determine markers of active fractions. Six prenyl xanthones, including two new xanthones, garcimangosxanthones H and I, were isolated and identified by NMR and HRESIMS. The biomarker γ-mangostin displayed significant activity against the phytopathogen R. solanacearum with an IC50 of 34.7 ± 1.5 µg/mL; γ-mangostin affected the bacterial morphology at a concentration of 16.0 µg/mL as seen with a scanning electron microscope image, and it significantly repressed the virulence-associated genes HrpB, FihD, and PilT of R. solanacearum. γ-Mangostin also reduced the symptoms of bacterial wilt disease effectively that is caused by R. solanacearum in tomato and tobacco seedlings in vitro. These results suggested that the use of γ-mangostin from the mangosteen pericarp against R. solanacearum may be used as a natural bacteriostatic agent in agriculture.

A homoisoflavonoid and a fatty acid in common purslane (Portulaca oleracea L.) synergistically inhibit growth of Spodoptera litura larvae.

BACKGROUND: Portulaca oleracea L., common purslane, is an insecticidal plant that has been documented as a 'Chinese indigenous pesticide', and it is seldom visited by insects in the field. However, identification of anti-insect compounds and mechanisms of action are still unclear. RESULTS: Interplanting purslane with Chinese cabbage demonstrated that purslane may contain secondary compounds that S. litura avoids eating. Four compounds were isolated from P. oleracea by directed anti-insect activity, and their chemical structures were identified by NMR spectra as (9Z,11E,15Z)-13-hydroxyoctadeca-9,11,15-trienoic acid (1), portulacanone A (2), portulacanone D (3), and a new natural product 2,4'-dihydroxy-3',5'-dimethoxychalcone (4). A combination of compound 1 and 2 possessed stronger activity than other combinations (compounds 1 + 3; 1 + 4; 2 + 3; 2 + 4; 3 + 4). Both active compounds were detected in all samples from 23 regions in China, and concentrations in samples collected from 17 regions were generally above 500 µg/kg. Concentrations of compounds 1 and 2 fluctuated greatly from April to November, and reached maximum concentrations of 45 951.44 µg/kg for compound 1 and 3739.09 µg/kg for compound 2 in November. The combination of these compounds (1 + 2) caused mid-gut structural deformation and tissue decay as determined by mid-gut histopathology of S. litura. CONCLUSION: In general, these active compounds coexisting contributed to partly protect purslane from insects. This research also provides new insights into the use of purslane as important ingredient of botanical pesticide alternatives to traditional chemical pesticides. © 2019 Society of Chemical Industry.