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Lecanicillium lecanii is an important entomopathogenic fungus which is used as a biopesticide for control of sucking insects. However, low fungicide-tolerance limits its application in the field. To improve the propamocarb-tolerance of L. lecanii , an optimized UV-light radiation-based mutagenesis system was established. The radiation time was optimized to 60 s for L. lecanii in the first round of UV-light radiation when a 20 Watt germicidal lamp was placed at a distance of 45 cm from plates. Both the positive mutation rate and EC 50 value of the UV-mutant were the highest when using this radiation time. The tolerance ratio (TR) was always lower than 1.13 in the first round of UV-light radiation. To further increase fungal propamocarb-tolerance, the highest propamocarb-tolerant mutant in the first round of UV-light radiation was used as a starting strain for multiple rounds of UV-light radiation in which a same germicidal lamp and radiation parameter were applied as described in the first round of UV-light radiation. TR was largely accumulated to 2.13 on the fourth round of radiation, and then began to level off and remained constant. A higher propamocarb-tolerant mutant was obtained in the sixth-round UV-light radiation, whose median effective concentration (EC 50 ) value was increased 2.15-fold compared to the wild-type strain, and it was mitotically stable in 20 passages on PDAY medium. This mutant did not show any significant changes of conidial yield on plates and virulence on aphids, although its colony growth was significantly lower than that of the wild-type strain. After the application of propamocarb at a recommended field dose of 550 μg/ml, the interval time of using L. lecanii was significantly shortened in this mutant compared to the wild-type strain. The results indicated that this improved strain could be potentially applied in combination with propamocarb in the field.

Transgenic cotton GK 12 producing Cry1Ab/Ac proteins can effectively control lepidopteran pests in agriculture. However, there are concerns that GK 12 has unintended side-effects on actinobacterial communities in the soil. Actinobacterial communities in the rhizosphere soil of cottons were analyzed by real-time PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) at different growth stages in three annual replications under field conditions. Population sizes and community structures of Actinobacteria were markedly affected by natural variations in years, growth stages and cultivars. No significant differences were found in population sizes (excepting at budding in 2009), community structures, and Shannon indices of Actinobacteria (excepting at budding in 2010) between the GK 12 and its non-transgenic parent Simian 3, although there were differences between the GK 12 and the conventional cotton DP 5415. Phylogenetic analysis of DGGE band sequences indicated that Cellulosimicrobium sp. and Rhodococcus sp. only occurred in the GK 12 and the Simian 3. The dominant Actinobacteria did not differ between the GK 12 and the Simian 3. In conclusion, the overall impacts of the GK 12 on actinobacterial communities in the rhizosphere soil, based on qPCR and DGGE, were not significant during three continuous years in northern China.

Transgenic cotton GK 12 expressing insecticidal Cry1Ab/1Ac gene can effectively control the lepidopteran pests in agriculture, however it may have unintended side-effects on soil fungal communities. Therefore, the fungal community size and structure in rhizosphere soil of Bt and non-Bt cottons were analyzed by real-time polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE) at growth stages and three annual replications in an intensive conventional cultivation system. The Cry1Ab/1Ac protein was undetectable or occasionally detectable at a low level (

Background Lecanicillium lecanii has been developed as a biopesticide and used in biological control of several agricultural insects. To improve fungal virulence, an optimised polyethylene glycol (PEG)-mediated protoplast transformation system was established for L. lecanii. Pr1A-like cuticle-degrading protease gene (Cdep1) from Beauveria bassiana was transferred into L. lecanii, and its resulting activity against Aphis gossypii was assessed. Results The optimised protoplast generation yielded 2.5 × 10(8) protoplasts g(-1) wet mycelium of fungi, and gave nearly 98% viability and 80% regeneration on plates. Protease activities were increased about fivefold in transformants expressing CDEP1. The median lethal concentration (LC50 ) for transformants expressing CDEP1 was twofold lower than that for the wild type (WT). The median survival time (LT50 ) for transformants expressing CDEP1 was also 14.2% shorter than that for WT, though no significant difference. There were no significant differences in conidial germination as colony growth and conidial yield on plates between transformants expressing CDEP1 and WT. The transformants expressing CDEP1 grew significantly quicker than WT in insects. The transformants expressing CDEP1 were lower in conidial yields on insect cadavers, but insignificantly different from WT. Conclusion The PEG-mediated protoplast transformation system was effective for L. lecanii, and the expression of CDEP1 significantly enhanced fungal virulence against cotton aphids. © 2016 Society of Chemical Industry.

This paper reports zircon LA-ICP-MS U–Pb ages and Hf–O isotopic ratios, and whole-rock major and trace element data of Early Cretaceous felsic intrusive rocks from Nagqu area, the northern Lhasa subterrane, southern Tibet. LA-ICP-MS zircon U–Pb dating of biotite granites and biotite monzogranites in the area yields magmatic crystallization ages of ca. 112 Ma, which suggests that they were emplaced in the late Early Cretaceous. Both rocks show high-K calc-alkaline to shoshonitic composition and slightly–moderately peraluminous signature. They are enriched in the alkalis, Rb, Th, K, U and light rare earth elements, depleted in Nb, Ta, Ti and P, and characterized by high Al 2 O 3 contents (12–16 wt.%), high Rb/Sr ratios (1.3–33) and low Mg # values (15–39). Their magmatic zircons have negative e Hf (t) values (from − 25.9 to 0.5) and high positive δ 18 O values (from 7.9‰ to 11.5‰). All the above characteristics indicate that Nagqu biotite monzogranites and biotite granites were likely derived from hybrid melts of sediments from the continent crust with minor mantle-derived input, then experienced varied degrees of fractional crystallization. The Nagqu intrusion is a component of the late Early Cretaceous magmatic flare-up event that occurred during ~ 120–100 Ma in the northern and partly central Lhasa subterranes. This magmatic flare-up is marked with a great compositional diversity (basalt, rhyolite, adakitic rocks, dioritic enclave, biotite monzogranite and granite) that might be caused by the slab breakoff of the southward subducting Bangong–Nujiang oceanic lithosphere, or more likely by slab window opening, which may have significantly contributed to juvenile crustal growth of the northern Lhasa subterrane.

Lecanicillium lecanii has been developed as a biopesticide and used in biological control of several agricultural insects. To improve fungal virulence, an optimised polyethylene glycol (PEG)-mediated protoplast transformation system was established for L. lecanii. Pr1A-like cuticle-degrading protease gene (Cdep1) from Beauveria bassiana was transferred into L. lecanii, and its resulting activity against Aphis gossypii was assessed.The optimised protoplast generation yielded 2.5 × 10(8) protoplasts g(-1) wet mycelium of fungi, and gave nearly 98% viability and 80% regeneration on plates. Protease activities were increased about fivefold in transformants expressing CDEP1. The median lethal concentration (LC50 ) for transformants expressing CDEP1 was twofold lower than that for the wild type (WT). The median survival time (LT50 ) for transformants expressing CDEP1 was also 14.2% shorter than that for WT, though no significant difference. There were no significant differences in conidial germination as colony growth and conidial yield on plates between transformants expressing CDEP1 and WT. The transformants expressing CDEP1 grew significantly quicker than WT in insects. The transformants expressing CDEP1 were lower in conidial yields on insect cadavers, but insignificantly different from WT.The PEG-mediated protoplast transformation system was effective for L. lecanii, and the expression of CDEP1 significantly enhanced fungal virulence against cotton aphids. © 2016 Society of Chemical Industry.

The entomopathogenic fungus L. lecanii has been developed as biopesticides and used widely for biological control of several insects in agricultural practice. Due to the lack of isolation/count methods for L. lecanii in soil, the persistence of this fungus in soil appears to have attracted no attention. A selective medium and count method for L. lecanii in soil based on cetyl trimethyl ammonium bromide (CTAB) was developed, and then the persistence and viability of this fungus in soil were investigated under field conditions between 2012 and 2014. The results showed that the rate of recovery for L. lecanii in soil on the selective CTAB medium was satisfactory. The minimum CFUs for L. lecanii on the selective medium (0.5 g/L CTAB) was about 102 conidia/g soil. The L. lecanii density in soil declined quickly in the first month after inoculation with fungal conidia, kept stable for 6 to 10 months, and then decreased gradually until undetectable. L. lecanii could persist for at least 14 months in the agricultural soil of northern China. The colony growth, conidia yield and germination rate on plates, as well as the median lethal concentration or times (LC50 or LT50) to aphids, mycelium growth in aphids and sporulation on aphids of L. lecanii did not change significantly during the persistence in soil. In general, the count method developed here was a very useful tool for monitoring the dynamics of natural or introduced L. lecanii populations in soil, and the data on the persistence of L. lecanii in soil reported here were helpful for biological control and environmental risk assessment.