The herbicide bensulfuron-methyl inhibits rice seedling development by blocking calcium ion flux in the OsCNGC12 channel.

Identification of translocator protein-related genes involved in bensulfuron-methyl (BSM) uptake and transport in rice could facilitate the development of herbicide-tolerant cultivars by inactivating them. This study found that the OsCNGC12 mutants not only reduced BSM uptake but also compromised the Ca2 ⁺ efflux caused by BSM in the roots, regulating dynamic equilibrium of Ca2 ⁺ inside the cell and conferring non-target-site tolerance to BSM.

Comparison of Glyphosate-Degradation Ability of Aldo-Keto Reductase (AKR4) Proteins in Maize, Soybean and Rice.

Genes that participate in the degradation or isolation of glyphosate in plants are promising, for they endow crops with herbicide tolerance with a low glyphosate residue. Recently, the aldo-keto reductase (AKR4) gene in Echinochloa colona (EcAKR4) was identified as a naturally evolved glyphosate-metabolism enzyme. Here, we compared the glyphosate-degradation ability of theAKR4 proteins from maize, soybean and rice, which belong to a clade containing EcAKR4 in the phylogenetic tree, by incubation of glyphosate with AKR proteins both in vivo and in vitro. The results indicated that, except for OsALR1, the other proteins were characterized as glyphosate-metabolism enzymes, with ZmAKR4 ranked the highest activity, and OsAKR4-1 and OsAKR4-2 exhibiting the highest activity among the AKR4 family in rice. Moreover, OsAKR4-1 was confirmed to endow glyphosate-tolerance at the plant level. Our study provides information on the mechanism underlying the glyphosate-degradation ability of AKR proteins in crops, which enables the development of glyphosate-resistant crops with a low glyphosate residue, mediated by AKRs.

Persistence of Metarhizium (Hypocreales: Clavicipitaceae) and Beauveria bassiana (Hypocreales: Clavicipitaceae) in Tobacco Soils and Potential as Biocontrol Agents of Spodoptera litura (Lepidoptera: Noctuidae).

Entomopathogenic fungi (EPF), such as Metarhizium spp. and Beauveria bassiana, are widely used in the biocontrol of many species of insect pests. Tobacco is an economically important crop in Guangdong Province of China, but insect pests, such as Spodoptera litura Fabricius, are a major threat to production. Here, we tested the persistence of five Metarhizium species and B. bassiana in glasshouse pot and field experiments and assessed their long-term efficacy against S. litura. We found that the colony forming units of these EPF decreased by c. 93% by 180 d in the pot soils declines tended to be exponential. In contrast, declines of c. 99% in field soils were more gradual (linear), occurring throughout the 360 d experiment. Metarhizium anisopliae Ma09 had the longest estimated half-life of 41 d, while that of B. bassiana was the shortest (9 d). Fungal density in the upper soil layer (0-5 cm) decreased rapidly and was undetectable after 150 d, whereas density was consistently greatest in the mid-layer (10-15 cm). At 180 d after inoculation, strain Ma09 elicited highest rates of mortality in S. litura. We conclude that soils in Guangdong Province are all suitable for the use of Metarhizium as a biocontrol agent, where M. anisopliae Ma09 offers greatest residual activity.

Decay of Quinclorac in Acidic Paddy Soil and Risk Evaluation to the Subsequent Crop, Tobacco (Nicotiana tabacum L.).

Quinclorac is a selective herbicide commonly used in China to control monocotyledonous weeds in paddy fields. A field experiment was conducted to quantify the environmental behavior of quinclorac in acidic paddy soil under rice (Oryza sativa L.) field conditions, and to evaluate the risk of its residues to the subsequent crop of tobacco (Nicotiana tabacum L.). Rice was sprayed once with quinclorac 50% WP at 562.5, 375.0, or 187.5 g a.i. ha-1 at 7 days after transplanting the seedlings. Decay of quinclorac in paddy field soil followed first-order kinetics, with a half-life of 28.29-30.27 days. At harvest time, 0.090, 0.074 and 0.034 mg kg-1 of quinclorac were found in soils following the above-described treatments, respectively. Leaves of the subsequent crop, tobacco, sown the year after the quinclorac treatments, exhibited different dose-dependent degrees of visible phytotoxicity symptoms.

Antibacterial activity of Lansiumamide B to tobacco bacterial wilt (Ralstonia solanacearum).

Tobacco bacterial wilt caused by Ralstonia solanacearum is one of the most serious diseases of tobacco in the area of tobacco cultivation. As there is no effective control method for tobacco bacterial wilt diseases, developing new antibacterial agents in tobacco will make great practical sense. The antibacterial activity against R. solanacearum of Lansiumamide B which is isolated from the seeds of Clausena lansium is reported in this paper for the first time. The bioassay results indicate that Lansiumamide B could completely inhibit the growth of R. solanacearum at the concentration of 125 mg/L in vitro, the EC50 and EC90 are 48.82 mg/L and 86.26 mg/L, respectively. The result of pot experiments indicates that the control efficiency of the Lansiumamide B on tobacco bacterial wilt are 95.84%, 91.67% and 86.38% at 7 days, 14 days and 21 days after treatment at the concentration of 100mg/kg, respectively, nearly 40 times higher than Streptomycin, a special fungicide to the disease, at 21 days after treatment with root irrigation method. These results suggest that Lansiumamide B has the potential of developing as a new type of plant-type fungicide on controlling the diseases of tobacco bacterial wilt.

Larvicidal activity of lansiumamide B from the seeds of Clausena lansium against Aedes albopictus (Diptera: Culicidae).

The larvicidal activity of crude petroleum ether, toluene, n-butanol, ethyl acetate, acetone, and methanol extracts of the seeds of Clausena lansium was assayed for their toxicities against the early fourth instar larvae of Aedes albopictus. The larval mortality was observed after 24-h exposure. The LC(50) value of petroleum ether extract was 22.99 ppm, showing the best larvicidal activity among all six solvent extracts. A cinnamon amide compound lansiumamide B (N-methyl-N-cis-styrylcinnamamide) was isolated from the petroleum ether extract by column chromatographic method, which exhibited a strong larvicidal activity against the early fourth instar larvae of A. albopictus with LC(50) and LC(90) values of 0.45 and 2.19 ppm, respectively. The structure was elucidated by (1)H NMR, (13)C NMR spectral data. The larvicidal activity against mosquito of lansiumamide B from the seed of C. lansium was evaluated for the first time.

Design, synthesis and antifungal/insecticidal evaluation of novel cinnamide derivatives.

Twenty novel cinnamamide derivatives were designed and synthesized using as lead compound pyrimorph, whose morpholine moiety was replaced by ß-phenylethylamine. All the compounds were characterized by their spectroscopic data. The fungicidal and insecticidal activities were also evaluated. The preliminary results showed that all the title compounds had certain fungicidal activities against seven plant pathogens at a concentration of 50 µg/mL, and compounds 11a and 11l showed inhibition ratios of up to 90% against R. solani. Most of the title compounds exhibited moderate nematicidal activities. In general, the morpholine ring may be replaced by other amines and a chlorine atom in the pyridine ring is helpful to fungicidal activity.

Studies of O,O-dimethyl α-(2,4-dichlorophenoxyacetoxy)ethylphosphonate (HW02) as a new herbicide. 1. Synthesis and herbicidal activity of HW02 and analogues as novel inhibitors of pyruvate dehydrogenase complex.

On the basis of the previous work for optimization of O,O-diethyl α-(substituted phenoxyacetoxy)alkylphosphonates, further extensive synthetic modifications were made to the substituents in alkylphosphonate and phenoxy moieties of the title compounds. New O,O-dimethyl α-(substituted phenoxyacetoxy)alkylphosphonates were synthesized as potential inhibitors of pyruvate dehydorogenase complex (PDHc). Their herbicidal activity and efficacy in vitro against PDHc were examined. Some of these compounds exhibited significant herbicidal activity and were demonstrated to be effective inhibitors of PDHc from three different plants. The structure-activity relationships of these compounds including previously reported analogous compounds were studied by examining their herbicidal activities. Both inhibitory potency against PDHc and herbicidal activity of title compounds could be increased greatly by optimizing substituent groups of the title compounds. O,O-Dimethyl α-(2,4-dichlorophenoxyacetoxy)ethylphosphonate (I-5), which acted as a competitive inhibitor of PDHc with much higher inhibitory potency against PDHc from Pisum sativum and Phaseolus radiatus than from Oryza sativa , was found to be the most effective compound against broadleaf weeds and showed potential utility as herbicide.