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Yang X.,Anhui Academy of Agricultural Sciences | Yang X.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | Yi X.-K.,Anhui Academy of Agricultural Sciences | Yi X.-K.,CAS Hefei Institutes of Physical Science | And 12 more authors.
Genetics and Molecular Research | Year: 2015

Bacterial canker, caused by Pseudomonas syringae pv. actinidiae, is one of the most severe diseases of kiwifruit. It has become an international pandemic and threatens the sustainable development of kiwifruit production in all main kiwi-growing regions worldwide. Streptomycin has been the major bactericide for the control of kiwifruit canker, especially in Anhui Province, one of the main kiwifruit production regions in China. However, until now, no studies on the baseline sensitivity to streptomycin of field isolates of P. syringae pv. actinidiae from China have been available. During 2012-2013, a total of 102 single-colony P. syringae pv. actinidiae strains were isolated: 36, 12, 13, 26, and 15 strains from Yuexi, Jinzhai, Huoshan, Qianshan, and Taihu counties, respectively. All strains were confirmed by production of a 280-bp fragment using the specific primers PsaF1/R2 upon polymerase chain reaction amplification, followed by an assay for confirmation of pathogenicity to fulfill Koch’s postulates. In this study, the streptomycin sensitivity of the 102 isolated strains was determined. The half-maximal effective concentration values for inhibition of growth by streptomycin were 0.03-0.42 μg/mL (average 0.12 ± 0.06 μg/mL). The baseline sensitivity curve was unimodal, representing range-of-variation factors of 14.0. No resistant subpopulation was identified among the strains used in the study. Thus, these sensitivity data could be used as a baseline for monitoring the shift in sensitivity of P. syringae pv. actinidiae populations to streptomycin in Anhui Province. Continuous resistance monitoring should be carried out, as streptomycin is an at-risk bactericide agent. © FUNPEC-RP.


Chen Y.,Anhui Academy of Agricultural Sciences | Chen Y.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | Yang X.,Anhui Academy of Agricultural Sciences | Yang X.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | And 12 more authors.
Annals of Applied Biology | Year: 2015

Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv oryzae, is one of the most serious bacterial diseases in China. Presently, bismerthiazol has been the major bactericide for the control of BLB, however, bismerthiazol-resistant strains of X. oryzae pv. oryzae have appeared in the field in China. Zinc thiazole is a novel bactericide with strong antibacterial activity against Xanthomonas spp. In this study, sensitivity of 109 X. oryzae pv. oryzae strains to zinc thiazole was determined. The EC50 values for zinc thiazole in inhibiting bacterial growth of the 109 X. oryzae pv. oryzae strains were 0.53-9.62 μg mL-1 with the average EC50 value of 4.82 ± 1.86 μg/ml. The minimum inhibitory concentration (MIC) values of zinc thiazole against the 109 X. oryzae pv. oryzae strains were assessed and the results showed that the MIC values of zinc thiazole for completely inhibiting the growth of these 109 strains ranged from 5.0 to 40.0 μg mL-1. In the evaluation of protective and curative activity test, zinc thiazole exhibited great activity against BLB and provided over 88% control efficacy (at 300 μg mL-1) 1 and 3 days before or after inoculations, which was also higher that that of bismerthiazol in the corresponding treatments. Our field trials showed that zinc thiazole at 375 g.a.i ha-1 provided over 70% control efficacy in 2012 and over 80% control efficacy in 2013 at both sites. Moreover, in all the four field trials, zinc thiazole at 250 g.a.i ha-1 provided higher control efficacy than that of bismerthiazol at 250 g.a.i ha-1. Taken together, zinc thiazole is therefore an alternative tool for the management of BLB. © 2014 Association of Applied Biologists.


Chen Y.,Anhui Academy of Agricultural Sciences | Chen Y.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | Yang X.,Anhui Academy of Agricultural Sciences | Yang X.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | And 7 more authors.
Plant Disease | Year: 2015

Fusarium asiaticum is a causal agent of Fusarium head blight (FHB) of wheat in the southern part of China. Carbendazim has been extensively used for controlling FHB for more than 30 years, leading to the widespread carbendazim-resistant isolates in all major wheat-producing provinces in China, especially in Anhui Province. F. asiaticum isolates were collected throughout Anhui Province between 2010 and 2012 to monitor their sensitivity to carbendazim. In total, 74 of 899 singlespore isolates F. asiaticum were found to be resistant to carbendazim. Resistant isolates were collected from all of the sampled sites except Hefei of Anhui Province. The overall frequency of carbendazim resistance was shown to be 8.2%. Of the 74 isolates, 1, 68, and 5 had low resistance (LR), moderate resistance (MR),and high resistance (HR), respectively, to carbendazim. Five types of point mutations (F167Y, E198L, E198K, F200Y, and E198Q) in the 2-tubulin gene conferring resistance to carbendazim were detected in the field-resistant isolates with frequencies of 89.2, 2.7, 4.1, 2.7, and 1.4%, respectively. The point mutations at codon 167, 198, or 200 of the 2-tubulin gene were correlated with different levels of carbendazim resistance. Some of the sensitive and resistant isolates appeared to possess different biological characteristics; however, these might not be due to resistance. Because carbendazim resistance was generally widespread throughout Anhui Province, the sensitivity of F. asiaticum populations to carbendazim should be constantly monitored for the development of carbendazim resistance in natural populations. © 2015 The American Phytopathological Society


Chen Y.,Anhui Academy of Agricultural Sciences | Chen Y.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | Yang X.,Anhui Academy of Agricultural Sciences | Yang X.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | And 7 more authors.
Annals of Applied Biology | Year: 2015

Sensitivity to azoxystrobin and kresoxim-methyl of 80 single-spore isolates of Magnaporthe oryzae was determined. The EC50 values for azoxystrobin and kresoxim-methyl in inhibiting mycelial growth of the 80 M. oryzae isolates were 0.006-0.056 and 0.024-0.287 μg mL-1, respectively. The EC50 values for azoxystrobin and kresoxim-methyl in inhibiting conidial germination of the M. oryzae populations were 0.004-0.051 and 0.012-0.105 μg mL-1, respectively. There was significant difference in sensitivity to azoxystrobin or kresoxim-methyl between the tested isolates representing differential sensitivity to carbendazim (MBC) and kitazin P (IBP); however, there was no correlation between this difference in sensitivity to azoxystrobin or kresoxim-methyl and sensitivity to MBC or IBP, indicating that there was no cross-resistance between azoxystrobin or kresoxim-methyl and MBC or IBP. In the protective and curative experiments, kresoxim-methyl exhibited higher protective and curative activity than azoxystrobin when applied at 150 and 250 μg mL-1 accordingly, while azoxystrobin exhibited stronger inhibitory activity against M. oryzae isolates than that of kresoxim-methyl in the in vitro test. The results of field experiments also suggested that both azoxystrobin and kresoxim-methyl at 187.5 g.a.i. ha-1 gave over 73% control efficacy in both sites, exhibiting excellent activity against rice blast. Taken together, azoxystrobin and kresoxim-methyl could be a good substitute for MBC or IBP for controlling rice blast in China, but should be carefully used as they were both at-risk. © 2015 Association of Applied Biologists.


Chen Y.,Anhui Academy of Agricultural Sciences | Chen Y.,Laboratory of Quality and Safety Risk Assessment for Agro Products Hefei | Yao J.,Anhui Entry Exit Inspection and Quarantine Bureau | Li Y.-F.,Anhui Entry Exit Inspection and Quarantine Bureau | And 6 more authors.
Phytoparasitica | Year: 2014

A method for simple and rapid detection of Ustilaginoidea virens in rice seeds was developed based on specific polymerase chain reaction (PCR). To design the specific primers for detection of U. virens, the comparison was made on 5.8S rDNA intra- and inter-specific variations in nucleotide sequences of U. virens and other pathogens: Fusarium verticillioides, Sclerotinia sclerotiorum, Tilletia barclayana, Fusarium graminearum and Magnaporthe oryzae. A 346-bp fragment could be amplified by using the specific primers uvr-F and uvr-R in U. virens, but not in other test fungi, indicating that the designed primers were specific for the detection of U. virens. U. virens was detected in nine of the 24 tested rice samples, indicating that 37.5% of the rice samples were contaminated with the false smut pathogen. The development of the simple and rapid detection technique using specific primers will be applicable for direct identification of U. virens in rice seeds to screen large numbers of samples. © 2013 Springer Science+Business Media Dordrecht.

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