Effect of low-temperature stress on the survival of Meloidogyne incognita and its application in greenhouse of northern China.

We examined the effects of low temperature on egg hatching and killing rate of the 2nd instars of Meloi-dogyne incognita (J2) in the laboratory. We further evaluated the effects of two soil treatment methods on the survival rate of M. incognita in northern China in a field experiment. The results of laboratory experiment showed that survival rate of J2 was 0 after being subjected to -7 ℃ for 24 hours, and that egg hatching was completely inhibited 24 hours after being subjected to -9 ℃. The survival rate of J2 was 0 after being subjected to -1, -2, -3, and -4 ℃ for 8, 5, 3, and 1.5 d, respectively. Egg hatching was completely inhibited after being subjected to -2, -3, -4, and -5 ℃ for 9, 6, 4, and 1 d, respectively. Results of the fitting analysis showed that both the relationships between the temperature and the lethal time of J2 as well as the temperature and the non-hatching time of the eggs followed exponential functions. The results of field test showed that death rate of M. incognita in 0-50 cm soil layer after ridging treatment and 0-30 cm soil layer after leveling treatment could reach 100%, while the disease index of the former in 30-40 cm and 40-50 cm was 84.9% and 75.8%, respectively, which was lower than that in the greenhouse. Our results suggest that preventing and controlling M. incognita in greenhouses through low-tempe-rature in winter could achieve a better control effect in Yulin City and the northward region. The proposed technique is convenient and has high potential for popularization.

[Barrier effect against Bemisia tabaci and the control of tomato yellow leaf curl virus in a tomato-maize intercropping system]. / ç•ªèŒ„çŽ‰ç±³é—´å¥—ä½œå¯¹çƒŸç²‰è™±çš„å±éšœæ•ˆåº”åŠæŽ§åˆ¶ç•ªèŒ„é»„åŒ–æ›²å¶ç— æ¯’ç— çš„æ•ˆæžœ.

We examined the barrier effects against Bemisia tabaci and the potential to control the tomato yellow leaf curl virus (TYLCV) of different tomato-maize intercropping modes. Tomatoes (variety Jinshan 511) were planted at a fixed row distance either as a monoculture or together with maize (variety Xianyu 335) at the distances of 10, 20, and 30 cm. We investigated the viral index for TYLCV and the population density of B. tabaci. Compared with tomato monoculture, the natural barrier established by the maize stabilized the growth environment for tomato. When the maize spacing was 10, 20, and 30 cm, the average temperature of tomato plants from 6:00 to 20:00 decreased by 3.01, 2.26, and 1.45 ℃, the average relative humidity increased by 13.0%, 8.8%, and 6.0%, and the mean light intensity reduced by 26.1%, 20.4%, and 14.5%, respectively. The changes of those factors alleviated the adverse environmental conditions (i.e., intense light, high temperature, and lack of moisture) that promote the spread of virus-related diseases during the high-temperature period of the day, with the most effective planting distance for the maize being 10 cm. Our results suggested that the intercropping of tomato and maize had a barrier effect against B. tabaci and was able to control the TYLCV in tomato. When the planting distance for the maize was 10, 20, and 30 cm, the number of B. tabaci was 88.7%, 82.0%, and 73.9% lower than tomato monoculture, respectively. The TYLCV was inhibited, with the viral disease index being decreased by 67.3%, 59.4%, and 44.5%, respectively. Tomato-maize intercropping was also beneficial for tomato plant growth and fruit set, which could enhance tomato yield. Such effect was strengthened under higher maize density.

Three new pigment protein tyrosine phosphatases inhibitors from the insect parasite fungus Cordyceps gracilioides: terreusinone A, pinophilin C and cryptosporioptide A.

Three new pigment compounds--terreusinone A (1), pinophilin C (2) and cryptosporioptide A (3)-were isolated from a solid culture of Cordyceps gracilioides. The structures of these compounds were determined by extensive spectroscopic analysis including HRESIMS, 1D- and 2D-NMR. The structure of terreusinone A (1) was further confirmed by single-crystal X-ray crystallographic diffraction analysis. In an in vitro activity assay, 1, 2 and 3 exhibited high inhibitory activity against PTP1B, SHP2, CDC25B, LAR and SHP1. Terreusinone A (1) inhibited PTP1B, SHP2, CDC25B, LAR and SHP1 enzyme with IC50 values 12.5, >50, 4.1, 10.6, 5.6 µg/mL, respectively; pinophilin C (2) with IC50 values 6.8, 8.0, 4.5, 4.7, 3.4 µg/mL, respectively; and cryptosporioptide A (3) with IC50 values 7.3, 5.7, 7.6, >50, 4.9 µg/mL, respectively.

A novel oxybis cresol verticilatin with highly varying degrees of biological activities from the insect pathogenic fungus Paecilomyces verticillatus.

A novel oxybis cresol compound named verticilatin (1), together with two known compounds, 5-methylresorcinol (2) and 2,4-dihydroxy-3,6-dimethylbenzaldehyde (3), was isolated from cultures of the insect pathogenic fungi Paecilomyces verticillatus. The structures of compounds were determined by extensive spectroscopic analysis of HR-ESI-MS and 1D and 2D NMR including HSQC, HMBC, COSY, and ROESY. Fortunately, compound 1 exhibited significant inhibitory activities against CDC25B, cathepsin B, MEG2, and SHP2 enzyme, with IC50 values of 11.5, 3.5, 7.8, and 15 µg/ml, respectively.

Penostatin derivatives, a novel kind of protein phosphatase 1b inhibitors isolated from solid cultures of the entomogenous fungus Isaria tenuipes.

Protein tyrosine phosphatase 1B (PTP1B) is implicated as a negative regulator of insulin receptor (IR) signaling and a potential drug target for the treatment of type II diabetes and other associated metabolic syndromes. Therefore, small molecular inhibitors of PTP1B can be considered as an attractive approach for the design of new therapeutic agents of type II diabetes diseases. In a continuing search for new protein phosphatase inhibitors from fungi, we have isolated a new compound, named penostatin J (1), together with three known ones, penostatin C (2), penostatin A (3), and penostatin B (4), from cultures of the entomogenous fungus Isaria tenuipes. The structure of penostatin J (1) was elucidated by extensive spectroscopic analysis. We also demonstrate for the first time that penostatin derivatives exhibit the best PTP1B inhibitory action. These findings suggest that penostatin derivatives are a potential novel kind of PTP1B inhibitors.