Endophytic Bacillus amyloliquefaciens YTB1407 elicits resistance against two fungal pathogens in sweet potato (Ipomoea batatas (L.) Lam.).

The endophytic Bacillus amyloliquefaciens YTB1407 was previously reported to promote the growth of sweet potato (Ipomoea batatas cv. Yanshu 25). Here, we demonstrate in both in vitro and pot trial assays that pre-treatment with YTB1407 suspension could enhance resistance against root rot disease and black rot disease, caused by Fusarium solani Mart. Sacc. f. sp. batatas McClure and Ceratocystis fimbriata Ell. & Halst on sweet potato, respectively. When seedlings were infected with fungal pathogens at 10 days post irrigation, pre-treatment with YTB1407 suspension decreased these pathogens and YTB1407 bacterial biomass in sweet potato roots. The pre-treatment activated the expression of salicylic acid (SA)-responsive PR-1 gene, raised SA content, and reduced hydrogen peroxide (H2O2) in the host to resist F. solani, while it enhanced the expression levels of SA-responsive NPR1 and PR1 genes and increased SA content to resist C. fimbriata. The disease resistance control effect initiated by pre-treatment with YTB1407 for root rot pathogen (F. solani) was better than for black rot pathogen (C. fimbriata). The results indicated that Bacillus amyloliquefaciens YTB1407 played a pivotal role in enhancing resistance to two fungi pathogens in sweet potato, through production of some antifungal metabolites to decrease infection in the early stage as well as induction of SA-dependent systemic resistance.

Copper ions suppress abscisic acid biosynthesis to enhance defence against Phytophthora infestans in potato.

Copper-based antimicrobial compounds are widely and historically used to control plant diseases, such as late blight caused by Phytophthora infestans, which seriously affects the yield and quality of potato. We previously identified that copper ion (Cu2+ ) acts as an extremely sensitive elicitor to induce ethylene (ET)-dependent immunity in Arabidopsis. Here, we found that Cu2+ induces the defence response to P. infestans in potato. Cu2+ suppresses the transcription of the abscisic acid (ABA) biosynthetic genes StABA1 and StNCED1, resulting in decreased ABA content. Treatment with ABA or inhibitor fluridone made potato more susceptible or resistance to late blight, respectively. In addition, potato with knockdown of StABA1 or StNCED1 showed greater resistance to late blight, suggesting that ABA negatively regulates potato resistance to P. infestans. Cu2+ also promotes the rapid biosynthesis of ET. Potato plants treated with 1-aminocyclopropane-1-carboxylate showed enhanced resistance to late blight. Repressed expression of StEIN2 or StEIN3 resulted in enhanced transcription of StABA1 and StNCED1, accumulation of ABA and susceptibility to P. infestans. Consistently, StEIN3 directly binds to the promoter regions of StABA1 and StNCED1. Overall, we concluded that Cu2+ triggers the defence response to potato late blight by activating ET biosynthesis to inhibit the biosynthesis of ABA.

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We isolated the endophytic Bacillus amyloliquefaciens YTB1407 from the root of Panax quinquefolium, which has both biological control and growth promoting effects. To investigate its potential applications, a pot experiment of sweet potato was tested to assess the capacity of endophytic colonization of YTB1407 and the selection of its optimum concentration by investigating the performance of root characteristics on three time points in the whole early growth phase after irrigating with different concentrations of bacterial suspensions with treatment of sterile water as control. The activities of endogenous hormone IAA, ZR, t-ZR and IAA oxidase (IAAO, PPO, POD) were analyzed. The results showed that YTB1407 promoted the specific colonization of root system, the elongation of adventitious root and branch roots, and root activity in the early growth stage of sweet potato. At later growth stage, it formed greater fresh mass of absorption root and lower aboveground/root system mass ratio. YTB1407 suspensions with OD600 of 0.50 (T0.50) had more significant effect, which induced the highest fresh tuber mass and the largest effective tuber numbers of per plant at top cover stage. YTB1407 promoted the differentiation of adventitious roots into tubers at initial point of tuberization by increasing IAA content and the ratio of (t-ZR+ZR)/IAA, decreasing IAAO activity and enhancing PPO activity. Moreover, it promoted the differentiated roots into tubers at tuberization stage by keeping the higher content of IAA, lower ratio of (t-ZR+ZR)/IAA, and decreasing IAAO and PPO activities.

[Effects of deguelin on proliferation and apoptosis of MCF-7 breast cancer cells by phosphatidylinositol 3-kinase/Akt signaling pathway].

OBJECTIVE: To study the effects of deguelin on proliferation and apoptosis of human breast cancer cell line MCF-7 and on phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. METHODS: After treatment with 0, 1, 5, 10, 15 and 20 µmol/L of deguelin for 6, 24, 48 and 72 hours, the proliferation inhibition rate of MCF-7 cells was measured by cell counting kit-8 assay. Apoptosis rate of MCF-7 cells was detected with Annexin V-fluorescein isothiocyanate/propidium iodide double staining by flow cytometry and the apoptotic morphology was observed under a transmission electron microscope. After treatment with 0, 1 and 5 µmol/L of deguelin for 6 hours, 5 proteins involved in the PI3K/Akt signaling pathway were examined by Western blot analysis. RESULTS: Deguelin at doses of 5, 10, 15 and 20 µmol/L inhibited the proliferation of MCF-7 cells at 6, 24, 48 and 72 hours. There was a significant difference in each group compared with the control group (P<0.01). The inhibitory effect was more marked with increasing concentration and duration of treatment. There were statistical differences (P<0.05) among 5, 10, 15 and 20 µmol/L groups. However, 1 µmol/L of deguelin had no obvious effects on the proliferation of MCF-7 cells at 6, 24, 48 and 72 hours, showing no significant difference compared with control group (P>0.05). Deguelin at doses of 5, 10, 15 and 20 µmol/L induced apoptosis of MCF-7 cells at 6 hours. There were significant differences (P<0.01) in the early and late apoptosis rate between the treated groups and the control group. The typical apoptotic MCF-7 cells were observed under the transmission electron microscopy. However, 1 µmol/L of deguelin had no apparent effect in inducing apoptosis of MCF-7 cells at 6 hours. After treatment with 5 µmol/L of deguelin for 6 hours the expression of phosphorylated phosphatase and tensin homologue deleted on chromosome 10 (PTEN) (Ser380), phosphorylated 3-phosphoinositide-dependent protein kinase 1 (PDK1) (Ser241), phosphorylated Akt (Thr308) and phosphorylated glycogen synthase kinase-3ß (GSK-3ß) (Ser9) proteins were significantly reduced in MCF-7 cells, while there was no significant change in the expression of total Akt protein. However, after treatment with 1 µmol/L of deguelin for 6 hours, there was no apparent change in the expression of these 5 proteins. CONCLUSION: Deguelin can inhibit the phosphorylation of GSK-3ß (Ser9) via inhibition of the phosphorylation of PTEN (Ser380) and PDK1 (Ser241) pathway, thus inducing apoptosis and inhibiting proliferation of MCF-7 cells.

Control of the pattern-recognition receptor EFR by an ER protein complex in plant immunity.

In plant innate immunity, the surface-exposed leucine-rich repeat receptor kinases EFR and FLS2 mediate recognition of the bacterial pathogen-associated molecular patterns EF-Tu and flagellin, respectively. We identified the Arabidopsis stromal-derived factor-2 (SDF2) as being required for EFR function, and to a lesser extent FLS2 function. SDF2 resides in an endoplasmic reticulum (ER) protein complex with the Hsp40 ERdj3B and the Hsp70 BiP, which are components of the ER-quality control (ER-QC). Loss of SDF2 results in ER retention and degradation of EFR. The differential requirement for ER-QC components by EFR and FLS2 could be linked to N-glycosylation mediated by STT3a, a catalytic subunit of the oligosaccharyltransferase complex involved in co-translational N-glycosylation. Our results show that the plasma membrane EFR requires the ER complex SDF2-ERdj3B-BiP for its proper accumulation, and provide a demonstration of a physiological requirement for ER-QC in transmembrane receptor function in plants. They also provide an unexpected differential requirement for ER-QC and N-glycosylation components by two closely related receptors.

[GIS-based analysis of spatio-temporal variability of groundwater nitrate concentration in high-yield region in North China Plain].

Nitrate pollution in groundwater is very widespread in intensive agricultural region. 394 samples from phreatic water wells and 283 samples from confined water wells were collected across Huantai County at the same season of 2002 and 2007, which is representative of high-yield region of North China Plain. The NO3- -N concentration was determined. Geostatistics combined with GIS technique were used to analyze the spatio-temporal variability of groundwater nitrate concentration. The average nitrate concentrations in phreatic water were 8.08 mg x L(-1) and 14.68 mg x L(-1) in 2002 and 2007 respectively, and that in confined water were 3.87 mg x L(-1) and 7.19 mg x L(-1) respectively. The spatial correlation distances of nitrate concentrations in confined water for both periods were greater than that in phreatic water. The mapping showed that the areas of phreatic groundwater with high levels of nitrate concentrations (10-15, 15-20, 20-30, and >30 mg x L(-1)) increased by 13.06%, 14.37%, 12.23%, and 3.85% from 2002 to 2007, while the area with low levels (0-5 and 5-10 mg x L(-1)) nitrate concentrations were decreased by 28.87% and 14.63% compared with 2002. However, the areas of confined water with nitrate concentrations of 5-10 mg x L(-1), 10-15 mg x L(-1) and 15-20 mg x L(-1) were increased by 28.01%, 9.33%, and 0.48% respectively, while the areas of NO3- -N concentration (0-5 mg x L(-1)) was decreased by 37.82%. The NO3- -N concentration in confined water was significantly negative related to groundwater depth for the two period, we found an increasing trend of NO3- -N concentration in the deeper confined water from 2002 to 2007.

[Effect of Endostatin and SU6668 combined with 5-FU on human colon cancer xenograft in nude mice].

OBJECTIVE: To investigate the effect of Endostatin and SU6668 combined with 5-FU on the growth and metastasis of human colon cancer in vivo and its mechanism. METHODS: Metastatic model of human colon cancer was established by orthotopic implantation of human tumor tissue into colon wall of nude mice. Twelve days later, mice were randomly divided into saline water control, Endostatin, SU6668, Endostatin plus SU6668, and Endostatin plus SU6668 and 5-FU groups, intraperitoneal injected respectively every day for four weeks. Six weeks after implication, the tumor weight, inhibition rates, intratumoral microvessel density (MVD) and metastasis were evaluated after the mice were sacrificed. RESULTS: Compared with the control, tumor growth was significantly inhibited in mice treated respectively with Endostatin, SU6668, Endostatin plus SU6668 and Endostatin plus SU6668 and 5-FU with an inhibition rate of 0, 64.9%, 63.5%, 76.4% and 88.2% respectively,and MVD decreased significantly in treated groups [(18.10+/-5.65) vs (2.75+/-0.75), (3.17+/-0.58), (0.94+/-0.42) and (0.36+/-0.45)]. The incidences of peritoneal and region lymph node metastases were significantly inhibited in Endostatin, SU6668, Endostatin plus SU6668 and Endostatin plus SU6668 and 5-FU (90% vs 16.7%, 25%, 0 and 0; 90% vs 0, 0, 0 and 0). The growth and metastasis of human colon cancer implanted in nude mice were significantly inhibited in Endostatin, SU6668, Endostatin plus SU6668, and Endostatin plus SU6668 and 5-FU, and the effect of Endostatin plus SU6668 and 5-FU was the most obviously. CONCLUSION: Endostatin plus SU6668 and 5-FU has strong inhibitory effect both on tumor growth and metastasis of human colon cancer.