Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is possibly the most important disease of Brassica worldwide. To compare chromosomal positions of Xcc resistance loci in Brassica oleracea between the p...Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is possibly the most important disease of Brassica worldwide. To compare chromosomal positions of Xcc resistance loci in Brassica oleracea between the present and published studies and to develop marker assisted selection (MAS) to resistance against Xcc race 1, we constructed a B. oleracea map, including pW, pX and BoCL markers that were closely linked to previously reported Xcc resistance QTLs. We also analyzed Xcc resistance QTLs by improving our previously reported map derived from the cross of a susceptible double-haploid line (GC P09) with a resistant double-haploid line (Reiho P01). In the nine linkage groups obtained (C1-C9), the major QTL, XccBo(Reiho)2, was derived from Reiho with a maximum LOD score (7.7) in C8. The QTL (LOD 4.4) located in C9, XccBo(GC)1 was derived from the susceptible GC. The other QTL (LOD 4.4), XccBo(Reiho)1, was found in C5. Based on common markers, it was possible to compare our finding Xcc resistance QTLs with the B. oleraceaXcc loci reported by previous authors;XccBo(Reiho)1 and XccBo(GC)1 may be identical to the Xcc resistance QTLs reported previously or a different member contained in the same resistance gene cluster. Our map includes public SSR markers linked to Xcc resistance genes that will promote pyramiding Xcc resistance genes in B. oleracea. The present study will also contribute to a better understanding of genetic control of Xcc resistance.展开更多
A phytotoxin from Xanthomonas campestris pv. retroflexus was isolated using a chromatographer and HPLC, and the components were identified to be a mixture of minor molecular compounds including organic acids and cyclo...A phytotoxin from Xanthomonas campestris pv. retroflexus was isolated using a chromatographer and HPLC, and the components were identified to be a mixture of minor molecular compounds including organic acids and cyclo-（proline-phenylalanine）. The greenhouse cultivation test was used to determine the influence of the isolated fractions on the growth of target weed redroot pigweed （Amaranthus retroflexus L）. The experimental results demonstrated that the cyclo-（Pro-Phe） had the weed inhibit activity obviously on dicotyledonous weed and the mixture with six organic acids showed stronger bioactivity. Further, greenhouse and field test were processed, and the test showed that the use of the toxin appeared to have the potential to be developed further as a bioherbicide system to control weedy grasses.展开更多
Bacterial spot(BS)is a severe bacterial disease induced by Xanthomonas campestris pv.vesicatoria(Xcv),a pathogen that causes serious damage to pepper growth and yield.It is therefore important to study the mechanisms ...Bacterial spot(BS)is a severe bacterial disease induced by Xanthomonas campestris pv.vesicatoria(Xcv),a pathogen that causes serious damage to pepper growth and yield.It is therefore important to study the mechanisms of pepper resistance to Xcv and to breed and promote Xcvresistant pepper varieties.However,studies of the responses to Xcv infection in peppers at the protein level are limited.Here,we examined Xcv-induced proteomic changes in leaves of the BS susceptible bell pepper ECW and the resistant bell pepper VI037601 using the isobaric tags for relative and absolute quantitation(iTRAQ)-based protein labeling technology.A total of 6,120 distinct proteins were identified,and there were 1,289 significantly differentially accumulated proteins(DAPs)in ECW and VI037601 leaves after Xcv inoculation.Among these,339(250up-and 89 down-regulated)and 479(300 up-and 179 down-regulated)DAPs were specifically identified in ECW and VI037601,respectively,with 459(364 up-and 95 down-regulated)similarly expressed DAPs being shared by ECW and VI037601.Based on bioinformatics analysis,many defense-associated proteins were identified as up-regulated in ECW and VI037601,especially the proteins involved in plant-pathogen interaction,phenylpropanoid biosynthesis,protein processing in the endoplasmic reticulum,and MAPK signaling pathway-plant.Moreover,we evaluated transcript levels of six differentially expressed genes from the iTRAQ results by q RT-PCR.The analysis revealed transcriptional changes that were consistent with the changes at the protein level.This study will provide a valuable resource for understanding the molecular basis of pepper resistance to Xcv infection and for improving the disease resistance of pepper cultivars.展开更多
Lettuce yields can be reduced by the disease bacterial leaf spot(BLS)caused by the pathogen Xanthomonas campestris pv.vitians(Xcv)and host resistance is the most feasible method to reduce disease losses.The cultivars ...Lettuce yields can be reduced by the disease bacterial leaf spot(BLS)caused by the pathogen Xanthomonas campestris pv.vitians(Xcv)and host resistance is the most feasible method to reduce disease losses.The cultivars La Brillante,Pavane and Little Gem express an incompatible host–pathogen interaction as a hypersensitive response(HR)to California strains of Xcv resulting in resistance.Little was known about the inheritance of resistance;however,resistance to other lettuce pathogens is often determined by resistance gene candidates(RGCs)encoding nucleotide-binding leucine-rich repeat(NB-LRR)proteins.Therefore,we determined the inheritance of BLS resistance in the cultivars La Brillante,Little Gem and Pavane and mapped it relative to RGCs.The reaction to Xcv was analyzed in nine F_(1),F_(2) and recombinant inbred line populations of lettuce from HR3compatible or HR3HR crosses.The HR in La Brillante,Pavane and Little Gem is conditioned by single dominant genes,which are either allelic or closely linked genes.The resistance gene in La Brillante was designated Xanthomonas resistance 1(Xar1)and mapped to lettuce linkage group 2.Xar1 is present in a genomic region that contains numerous NB-LRR encoding RGCs and functional pathogen resistance loci in the RGC2 family.The Xar1 gene confers a high level of BLS resistance in the greenhouse and field that can be introgressed into commercial lettuce cultivars to reduce BLS losses using molecular markers.展开更多
Mango bacterial canker is caused by Xanthomonas campestris pv. mangiferaeindicae. During 2009 and 2013,leaves,twigs and fruits of mango were collected from commercial and experimental mango fields with typical canker ...Mango bacterial canker is caused by Xanthomonas campestris pv. mangiferaeindicae. During 2009 and 2013,leaves,twigs and fruits of mango were collected from commercial and experimental mango fields with typical canker symptoms in Hainan,Guangxi,Guangdong and Szechwan Provinces of China. The causal agent was identified as X. campestris pv. mangiferaeindicae through KC semi-selective medium isolation,pathogenicity tests,and sequencing of the gyrB gene.展开更多
[Objective] This study aimed to develop a PCR assay for detecting Xanthomonas campestris pv. mangiferaeindicae(Xcm) in culture and in planta. [Method] Primers(Xcm HF and Xcm HR) were designed based on the partial sequ...[Objective] This study aimed to develop a PCR assay for detecting Xanthomonas campestris pv. mangiferaeindicae(Xcm) in culture and in planta. [Method] Primers(Xcm HF and Xcm HR) were designed based on the partial sequence of hrp B gene from xanthomonads to develop a PCR assay for Xcm. Furthermore, specificity and sensitivity of the primer pairs were analyzed in detection of genomic DNA and cell from Xcm. [Result] Amplication was positive only with genomic DNA from positive control ATCC11637 and 12 Xcm strains; no PCR products were amplified with genomic DNA from ten other xanthomonads and seven other bacterial species. The sensitivity of detection was 2.4 pg/μl genomic DNA, and 1.8 × 104CFU/ml cells. The primers also worked well for pathogen detection in direct PCR assays of Xcm colonies grown on liquid medium and in PCR assays of total DNA from leaf, branch and fruit lesions. [Conclusion] A PCR assay was successfully established for rapid detection of Xcm in culture and in planta.展开更多
The leaf, bark and seed extracts ofMoringa oleifera were evaluated for their efficacy under field conditions in suppressing Xanthomonas campestris pv. campestris in rape （Brassica napus. L.）. Xanthomonas campestris ...The leaf, bark and seed extracts ofMoringa oleifera were evaluated for their efficacy under field conditions in suppressing Xanthomonas campestris pv. campestris in rape （Brassica napus. L.）. Xanthomonas campestris pv. campestris is an important bacterial pathogen of agricultural importance causing devastating black rot disease of Brassicas. Three extracts concentrations of 60, 100 and 140% were sprayed as foliar applications weekly and the antibacterial activity was evaluated by recording number of totally defoliated plants. The three extracts showed significant effect against the test pathogen （p 〉 0.05）. The antibacterial activity of seed extract demonstrated higher activity against the Xanthomonas campestris pv. campestris as evidenced by lower mean leaf defoliation of 1.59 cm followed by bark （2.58 cm） and lastly leaf extracts （2.96 cm） （p 〈 0.05）. There were no significant differences based on the concentration levels used. Observations revealed that 100% and 140% levels were not significantly different from each other on enhancing growth of the stem diameter. Moringa seed at 60% concentration level can be used to enhance growth of rape. The conclusion is that Moringa seed extracts can be effectively implemented to suppress Xanthomonas campestris pv. campestris pathogen in field grown rape in an integrated disease control program.展开更多
Bacterial proliferation in hosts requires activation of a number of housekeeping pathways, including purine de novo biosynthesis. Although inactivation of purine biosynthesis genes can attenuate virulence, it is uncle...Bacterial proliferation in hosts requires activation of a number of housekeeping pathways, including purine de novo biosynthesis. Although inactivation of purine biosynthesis genes can attenuate virulence, it is unclear which biochemical or virulence factors are associated with the purine biosynthesis pathway in vivo. We report that inactivation of purC, a gene encoding phosphoribosylaminoimidazole-succinocarboxamide synthase, caused complete loss of virulence in Xanthomonas campestris pv. cam- pestris, the causal agent of black rot disease of cruciferous plants. The purC mutant was a purine auxotroph; it could not grow on minimal medium, whereas addition of purine derivatives, such as hypoxanthine or adenine plus guanine, restored growth of the mutant. The purC mutation also significantly enhanced the production of an unknown purine synthesis associated pigment and extracellular polysaccharides by the bacterium. In addition, comparative proteomic analyses of bacteria grown on rich and minimal media revealed that the purC mutation affected the expression levels of diverse proteins involved in purine and pyrimidine synthesis, carbon and energy metabolisms, iron uptake, proteolysis, protein secretion, and signal transduction. These results provided clues to understanding the contributions of purine synthesis to bacterial virulence and interactions with host immune systems.展开更多
文摘Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is possibly the most important disease of Brassica worldwide. To compare chromosomal positions of Xcc resistance loci in Brassica oleracea between the present and published studies and to develop marker assisted selection (MAS) to resistance against Xcc race 1, we constructed a B. oleracea map, including pW, pX and BoCL markers that were closely linked to previously reported Xcc resistance QTLs. We also analyzed Xcc resistance QTLs by improving our previously reported map derived from the cross of a susceptible double-haploid line (GC P09) with a resistant double-haploid line (Reiho P01). In the nine linkage groups obtained (C1-C9), the major QTL, XccBo(Reiho)2, was derived from Reiho with a maximum LOD score (7.7) in C8. The QTL (LOD 4.4) located in C9, XccBo(GC)1 was derived from the susceptible GC. The other QTL (LOD 4.4), XccBo(Reiho)1, was found in C5. Based on common markers, it was possible to compare our finding Xcc resistance QTLs with the B. oleraceaXcc loci reported by previous authors;XccBo(Reiho)1 and XccBo(GC)1 may be identical to the Xcc resistance QTLs reported previously or a different member contained in the same resistance gene cluster. Our map includes public SSR markers linked to Xcc resistance genes that will promote pyramiding Xcc resistance genes in B. oleracea. The present study will also contribute to a better understanding of genetic control of Xcc resistance.
基金Supported by the National Natural Science Fotmdation of China （No.30370939）, Natural Science Foundation of Zhejiang Province （No.300054） and Science Research Plan of Zhejiang Province （No.2004C22005）.
文摘A phytotoxin from Xanthomonas campestris pv. retroflexus was isolated using a chromatographer and HPLC, and the components were identified to be a mixture of minor molecular compounds including organic acids and cyclo-（proline-phenylalanine）. The greenhouse cultivation test was used to determine the influence of the isolated fractions on the growth of target weed redroot pigweed （Amaranthus retroflexus L）. The experimental results demonstrated that the cyclo-（Pro-Phe） had the weed inhibit activity obviously on dicotyledonous weed and the mixture with six organic acids showed stronger bioactivity. Further, greenhouse and field test were processed, and the test showed that the use of the toxin appeared to have the potential to be developed further as a bioherbicide system to control weedy grasses.
基金supported by grants of the National Key R&D Program of China (Grants Nos.2016YFE0205500 and 2017YFD0101903)the earmarked fund for China Agriculture Research System (Grant No.CARS-23-G28)+2 种基金the China Postdoctoral Science Foundation (Grant No.2017M620305)Natural Science Foundation of Hubei Province (Grant No.2020CFA010)Youth Fund of Hubei Academy of Agricultural Sciences (Grant No.2021NKYJJ04)。
文摘Bacterial spot(BS)is a severe bacterial disease induced by Xanthomonas campestris pv.vesicatoria(Xcv),a pathogen that causes serious damage to pepper growth and yield.It is therefore important to study the mechanisms of pepper resistance to Xcv and to breed and promote Xcvresistant pepper varieties.However,studies of the responses to Xcv infection in peppers at the protein level are limited.Here,we examined Xcv-induced proteomic changes in leaves of the BS susceptible bell pepper ECW and the resistant bell pepper VI037601 using the isobaric tags for relative and absolute quantitation(iTRAQ)-based protein labeling technology.A total of 6,120 distinct proteins were identified,and there were 1,289 significantly differentially accumulated proteins(DAPs)in ECW and VI037601 leaves after Xcv inoculation.Among these,339(250up-and 89 down-regulated)and 479(300 up-and 179 down-regulated)DAPs were specifically identified in ECW and VI037601,respectively,with 459(364 up-and 95 down-regulated)similarly expressed DAPs being shared by ECW and VI037601.Based on bioinformatics analysis,many defense-associated proteins were identified as up-regulated in ECW and VI037601,especially the proteins involved in plant-pathogen interaction,phenylpropanoid biosynthesis,protein processing in the endoplasmic reticulum,and MAPK signaling pathway-plant.Moreover,we evaluated transcript levels of six differentially expressed genes from the iTRAQ results by q RT-PCR.The analysis revealed transcriptional changes that were consistent with the changes at the protein level.This study will provide a valuable resource for understanding the molecular basis of pepper resistance to Xcv infection and for improving the disease resistance of pepper cultivars.
基金This research was supported by the California Leafy Greens Research Program,the California Department of Food and Agriculture,USDA NRI(grant no.2008-35300-004447)USDA NIFA SCRI(grant no.2010-51181-21631).
文摘Lettuce yields can be reduced by the disease bacterial leaf spot(BLS)caused by the pathogen Xanthomonas campestris pv.vitians(Xcv)and host resistance is the most feasible method to reduce disease losses.The cultivars La Brillante,Pavane and Little Gem express an incompatible host–pathogen interaction as a hypersensitive response(HR)to California strains of Xcv resulting in resistance.Little was known about the inheritance of resistance;however,resistance to other lettuce pathogens is often determined by resistance gene candidates(RGCs)encoding nucleotide-binding leucine-rich repeat(NB-LRR)proteins.Therefore,we determined the inheritance of BLS resistance in the cultivars La Brillante,Little Gem and Pavane and mapped it relative to RGCs.The reaction to Xcv was analyzed in nine F_(1),F_(2) and recombinant inbred line populations of lettuce from HR3compatible or HR3HR crosses.The HR in La Brillante,Pavane and Little Gem is conditioned by single dominant genes,which are either allelic or closely linked genes.The resistance gene in La Brillante was designated Xanthomonas resistance 1(Xar1)and mapped to lettuce linkage group 2.Xar1 is present in a genomic region that contains numerous NB-LRR encoding RGCs and functional pathogen resistance loci in the RGC2 family.The Xar1 gene confers a high level of BLS resistance in the greenhouse and field that can be introgressed into commercial lettuce cultivars to reduce BLS losses using molecular markers.
基金Supported by the Ministry of Science and Technology and the Ministry of Agriculture of China(2014hzs1J007-2)
文摘Mango bacterial canker is caused by Xanthomonas campestris pv. mangiferaeindicae. During 2009 and 2013,leaves,twigs and fruits of mango were collected from commercial and experimental mango fields with typical canker symptoms in Hainan,Guangxi,Guangdong and Szechwan Provinces of China. The causal agent was identified as X. campestris pv. mangiferaeindicae through KC semi-selective medium isolation,pathogenicity tests,and sequencing of the gyrB gene.
基金Supported by Fundamental Scientific Research Fund of Chinese Academy of Tropical Agricultural Sciences(2014hzs1J007-2)
文摘[Objective] This study aimed to develop a PCR assay for detecting Xanthomonas campestris pv. mangiferaeindicae(Xcm) in culture and in planta. [Method] Primers(Xcm HF and Xcm HR) were designed based on the partial sequence of hrp B gene from xanthomonads to develop a PCR assay for Xcm. Furthermore, specificity and sensitivity of the primer pairs were analyzed in detection of genomic DNA and cell from Xcm. [Result] Amplication was positive only with genomic DNA from positive control ATCC11637 and 12 Xcm strains; no PCR products were amplified with genomic DNA from ten other xanthomonads and seven other bacterial species. The sensitivity of detection was 2.4 pg/μl genomic DNA, and 1.8 × 104CFU/ml cells. The primers also worked well for pathogen detection in direct PCR assays of Xcm colonies grown on liquid medium and in PCR assays of total DNA from leaf, branch and fruit lesions. [Conclusion] A PCR assay was successfully established for rapid detection of Xcm in culture and in planta.
文摘The leaf, bark and seed extracts ofMoringa oleifera were evaluated for their efficacy under field conditions in suppressing Xanthomonas campestris pv. campestris in rape （Brassica napus. L.）. Xanthomonas campestris pv. campestris is an important bacterial pathogen of agricultural importance causing devastating black rot disease of Brassicas. Three extracts concentrations of 60, 100 and 140% were sprayed as foliar applications weekly and the antibacterial activity was evaluated by recording number of totally defoliated plants. The three extracts showed significant effect against the test pathogen （p 〉 0.05）. The antibacterial activity of seed extract demonstrated higher activity against the Xanthomonas campestris pv. campestris as evidenced by lower mean leaf defoliation of 1.59 cm followed by bark （2.58 cm） and lastly leaf extracts （2.96 cm） （p 〈 0.05）. There were no significant differences based on the concentration levels used. Observations revealed that 100% and 140% levels were not significantly different from each other on enhancing growth of the stem diameter. Moringa seed at 60% concentration level can be used to enhance growth of rape. The conclusion is that Moringa seed extracts can be effectively implemented to suppress Xanthomonas campestris pv. campestris pathogen in field grown rape in an integrated disease control program.
基金supported by the grants from the National Basic Research Program of the Ministry of Science and Technology of China(No.2011CB100700)the National Science Foundation of China(Nos.31100065 and 31070081)the Basic Research of Frontiers of the Chinese Academy of Sciences(No.KSCX2-EW-J-6)
文摘Bacterial proliferation in hosts requires activation of a number of housekeeping pathways, including purine de novo biosynthesis. Although inactivation of purine biosynthesis genes can attenuate virulence, it is unclear which biochemical or virulence factors are associated with the purine biosynthesis pathway in vivo. We report that inactivation of purC, a gene encoding phosphoribosylaminoimidazole-succinocarboxamide synthase, caused complete loss of virulence in Xanthomonas campestris pv. cam- pestris, the causal agent of black rot disease of cruciferous plants. The purC mutant was a purine auxotroph; it could not grow on minimal medium, whereas addition of purine derivatives, such as hypoxanthine or adenine plus guanine, restored growth of the mutant. The purC mutation also significantly enhanced the production of an unknown purine synthesis associated pigment and extracellular polysaccharides by the bacterium. In addition, comparative proteomic analyses of bacteria grown on rich and minimal media revealed that the purC mutation affected the expression levels of diverse proteins involved in purine and pyrimidine synthesis, carbon and energy metabolisms, iron uptake, proteolysis, protein secretion, and signal transduction. These results provided clues to understanding the contributions of purine synthesis to bacterial virulence and interactions with host immune systems.
