Identification of differentially expressed genes of Xanthomonas axonopodis pv. citri by representational difference analysis of cDNA

Xanthomonas axonopodis pv. citri is a phytopathogenic bacterium responsible for citrus canker, a serious disease which causes severe losses in citriculture around the world. In this study we report the differential expression of X. axonopodis pv. citri in response to specific treatments by using Representational Difference Analysis of cDNA (cDNA RDA). cDNAs from X. axonopodis pv. citri cultured in the presence of leaf extract of the host plant (Citrus sinensis), in vivo, as well as in the complex medium were hybridized against cDNA of the bacterium grown in the minimal medium. Sequencing of the difference products obtained after the second and third hybridizations revealed a total of 37 distinct genes identified by homology searches in the genome of X. axonopodis pv. citri. These genes were distributed in different functional categories, including genes that encode hypothetical proteins, genes involved in metabolism, cellular processes and pathogenicity, and mobile genetic elements. Most of these genes are likely related to growth and/or acquisition of nutrients in specific treatments whereas others might be important for the bacterium pathogenicity.140149Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Efeitos de giberelinas no desenvolvimento do algodoeiro (Gossypium hirsutum L. cv.'IAC-RM3')

Seedlings of cotton were treated 19 days after the sowing with gibberellins at concentrations of 2, 20 and 200 ppm and the check to verify The effect of the compound on the growth of the plant. The experiment was done under greenhouse conditions in 1974. The main proposal of this work is to study the variation of plant height, net assimilation rate, relative growth rate and the leaf area ratio with application of gibberellins. The growth regulator at concentrations of 2, 20 and 200 ppm increased plant height, respectively in 27, 48 and 65% when compared to the control. Application of gibberellins at concentrations of 2 and 20 ppm promotes increase in the net assimilation rate and in the leaf area ratio of cotton. The relative growth rate was superior in the plots that received gibberelins at concentrations of 2, 20 and 200 ppm. It was verified that gibberellins at 200 ppm has a tendency to promote reduction in the net assimilation rate and slight variation in the leaf area ratio in relation to check.Verificou-se o efeito de giberelinas, quando aplicada sob a forma de pulverização das plântulas, no desenvolvimento do algodoeiro cultivar 'IAC-RM3' em condições de casa-de-vegetação. Estudaram-se as concentrações de 0, 2, 20 e 200 ppm do regulador de crescimento; sendo que os tratamentos aumentaram a altura das plantas em 27, 48 e 65%, com relação ao controle. Aplicações de giberelinas nas dosagens de 2 e 20 ppm promoveram aumento na TAL e na RAF do algodoeiro. A TCR foi superior nas plantas tratadas com giberelinas. Verificou-se ainda que giberelinas a 200 ppm promove redução na TAL e variação mínima na RAF, com relação ao controle

Identification of differentially expressed genes of Xanthomonas axonopodis pv. citri by representational difference analysis of cDNA

Xanthomonas axonopodis pv. citri is a phytopathogenic bacterium responsible for citrus canker, a serious disease which causes severe losses in citriculture around the world. In this study we report the differential expression of X. axonopodis pv. citri in response to specific treatments by using Representational Difference Analysis of cDNA (cDNA RDA). cDNAs from X. axonopodis pv. citri cultured in the presence of leaf extract of the host plant (Citrus sinensis), in vivo, as well as in the complex medium were hybridized against cDNA of the bacterium grown in the minimal medium. Sequencing of the difference products obtained after the second and third hybridizations revealed a total of 37 distinct genes identified by homology searches in the genome of X. axonopodis pv. citri. These genes were distributed in different functional categories, including genes that encode hypothetical proteins, genes involved in metabolism, cellular processes and pathogenicity, and mobile genetic elements. Most of these genes are likely related to growth and/or acquisition of nutrients in specific treatments whereas others might be important for the bacterium pathogenicity

Eric- And Rep-pcr Amplify Non-repetitive Fragments From The Genome Of Drechslera Avenae And Stemphylium Solani.

In the present study, the homology relationships among fragments amplified by ERIC (Enterobacterial Repetitive Intergenic Consensus) and REP (Repetitive Extragenic Palindromic) primers in Drechslera avenae and Stemphylium solani causing leaf blotch and black spot of oats and leaf blight of cotton, respectively, were investigated by Southern hybridization followed by DNA sequencing. ERIC- and REP-PCR were performed for 24 isolates of D. avenae and 33 isolates of S. solani. The banding patterns obtained were transferred to nylon membranes and a total of 16 fragments, four ERIC and four REP bands from each fungus, used as probes. The hybridization and DNA sequencing revealed a low degree of similarity among the bands indicating that the regions amplified by these primers are not repetitive and that the primers anneal at random regions in the genomes of D. avenae and S. solani.21151-

Microarray Analyses of Xylella fastidiosa Provide Evidence of Coordinated Transcription Control of Laterally Transferred Elements

Genetically distinct strains of the plant bacterium Xylella fastidiosa (Xf) are responsible for a variety of plant diseases, accounting for severe economic damage throughout the world. Using as a reference the genome of Xf 9a5c strain, associated with citrus variegated chlorosis (CVC), we developed a microarray-based comparison involving 12 Xf isolates, providing a thorough assessment of the variation in genomic composition across the group. Our results demonstrate that Xf displays one of the largest flexible gene pools characterized to date, with several horizontally acquired elements, such as prophages, plasmids, and genomic islands (GIs), which contribute up to 18% of the final genome. Transcriptome analysis of bacteria grown under different conditions shows that most of these elements are transcriptionally active, and their expression can be influenced in a coordinated manner by environmental stimuli. Finally, evaluation of the genetic composition of these laterally transferred elements identified differences that may help to explain the adaptability of Xf strains to infect such a wide range of plant species. [Supplemental material is available online at www.genome.org.