ABSTRACT
Citrus canker, caused by the Gram-negative bacterium Xanthomonas citri subsp citri (Xac), is a major disease affecting citriculture worldwide, because of the susceptibility of the host and the lack of efficient control methods. Previous studies have reported that some genes of phytopathogenic bacteria possess a consensus nucleotide sequence (TTCGC...N15...TTCGC) designated the "plant-inducible-promoter box" (PIP box) located in the promoter region, which is responsible for activating the expression of pathogenicity and virulence factors when the pathogen is in contact with the host plant. In this study, we mapped and investigated the expression of 104 Xac genes associated with the PIP box sequences using a macroarray analysis. Xac gene expression was observed during in vitro (Xac grown for 12 or 20 h in XAM1 induction medium) or in vivo (bacteria grown in orange leaves for 3 to 5 days) infection conditions. Xac grown in non-induction NB liquid medium was used as the control. cDNA was isolated from bacteria grown under the different conditions and hybridized to the macroarray, and 32 genes differentially expressed during the infection period (in vitro or in vivo induction) were identified. The macroarray results were validated for some of the genes through semi-quantitative RT-PCR, and the functionality of the PIP box-containing promoter was demonstrated by activating b-glucuronidase reporter gene activity by the PIP box-containing promoter region during Xac-citrus host interaction.
Subject(s)
Genes, Bacterial , Promoter Regions, Genetic , Xanthomonas/genetics , Gene Expression Regulation, Bacterial , Physical Chromosome Mapping , Virulence/genetics , Virulence Factors/genetics , Virulence Factors/metabolism , Xanthomonas/pathogenicityABSTRACT
Here, we report a quick and low-cost method to improve plant transformation using Agrobacterium tumefaciens. This method involves the use of physical wounding, ultrasound, and an increase in exposure time to the bacteria. We show how the transformation rate increased from 0 to 14% when an ultrasound pulse of 10 s was used in conjunction with 96 h of bacterial exposure in Eclipta alba explants.
Subject(s)
Agrobacterium tumefaciens/genetics , DNA, Bacterial/genetics , Eclipta/genetics , Plant Stems/genetics , Plants, Genetically Modified , Transformation, Genetic , Agrobacterium tumefaciens/metabolism , Anti-Bacterial Agents/pharmacology , DNA, Bacterial/metabolism , Eclipta/drug effects , Eclipta/microbiology , Eclipta/radiation effects , Genetic Vectors/chemistry , Genetic Vectors/metabolism , Kanamycin/pharmacology , Kanamycin Resistance , Plant Stems/drug effects , Plant Stems/microbiology , Plant Stems/radiation effects , Ultrasonic WavesABSTRACT
Random amplified polymorphic DNA (RAPD) was used to detect polymorphisms among Zaprionus indianus fly populations collected from six municipalities in the States of São Paulo and Minas Gerais, Brazil. This species is an important, recently introduced fruit fly pest of figs and other fruit. Among 21 primers, 16 produced 73 reproducible polymorphic fragments; primer AM-9 produced the greatest number of polymorphic bands (nine), with 52% genetic variability among populations. Genetic divergence analysis of the Z. indianus populations demonstrated two major groups, named Western and Eastern groups. There was greater gene flow within than between groups. The correlation coefficient for genetic and geographic distances (Mantel test) was significant, demonstrating isolation by distance.
