Genetic Diversity and Biocontrol of Rosellinia necatrix Infecting Apple in Northern Italy.

The soilborne fungus Rosellinia necatrix is the causal agent of white root rot disease on numerous plant species, including apple, which, together with the ability to survive in soil for long periods, makes this pathogen difficult to control. To understand the origins of pathogen infestation, a survey of diseased apple orchards in the northeast of Italy was conducted and 35 isolates of R. necatrix were characterized with intersimple sequence repeat markers. High genetic heterogeneity among the collected isolates suggested multiple preexisting sources of inoculum and not movement of infected soil or plant material from a single source. Greenhouse trials confirmed that, as with some other crops, soil water content and temperature were the main factors influencing infection of apple plants, while organic fertilizers and the incorporation of apple wood residues were less important. The efficacy of Trichoderma atroviride SC1 as a biocontrol agent against R. necatrix greatly depended on the timing of application. It reduced white root rot incidence on apple seedlings only if treatment was applied at least 1 week before planting.

Microarray analysis of differentially expressed mRNAs and miRNAs in young leaves of sorghum under dry-down conditions.

Sorghum is a C4 plant adapted to semi-arid environments, and characterized by high water-use efficiency. To better understand the molecular and physiological basis of drought response the sorghum genotype IS19453, selected as a drought tolerant line during field trials, was evaluated in a "dry-down" experiment under controlled conditions. The incoming stress was monitored by determining the water potential available for 4-leaf-old plants. Control plants were maintained at approximately 2.5 pF, while water stressed plants were sampled at 3.12, 3.65 and 4.14 pF. Transcriptome analysis was monitored using a high density microarray containing all available sorghum TC sequences. Drought affected gene expression at 4.14 pF; 1205 genes resulted up-regulated. Most of the differentially expressed genes were involved in regulation of transcription (bZIPs, MYBs, HOXs), signal transduction (phosphoesterases, kinases, phosphatases), carbon metabolism (NADP-ME), detoxification (CYPs, GST, AKRs), osmoprotection mechanisms (P5CS) and stability of protein membranes (DHN1, LEA, HSPs). Several of them could be located in stay green QTLs. Eight were selected and validated by qRT-PCR. A dedicated miRNA microarray allowed the identification of four families of miRNAs up-regulated in the earlier phase of stress, while one family was down-regulated. The selected drought related genes could be used to screen for potential drought tolerance in other sorghum genotypes.

Differential gene expression in kernels and silks of maize lines with contrasting levels of ear rot resistance after Fusarium verticillioides infection.

Fusarium verticillioides is the causal agent of ear rot in most maize-growing areas of southern Europe. F. verticillioides produces fumonisins commonly found at biologically significant concentrations in maize grain; the molecular interaction between the fungus and the plant is not well known, and little information is currently available about the defense response of maize against F. verticillioides infection. We attempted to identify genes that may be involved in Fusarium ear rot resistance using resistant and susceptible maize genotypes. Kernels of the resistant inbred showed significantly reduced incidence of infection by F. verticillioides, limited amounts of total fumonisin content and reduced fungal growth, as indicated by a lower copy number of ß-tubulin 2 and FUM 21 genes of F. verticillioides. Gene expression data were obtained from microarray hybridizations using maize seeds infected with F. verticillioides, by comparing seeds at 0 and 48h after infection. Differentially expressed sequences were identified and classified into 11 functional categories. Most of the differentially expressed genes were assigned to the category "cell rescue, defense and virulence" in both resistant and susceptible maize lines. These genes encode for PR proteins, detoxification enzymes and ß-glucosidases. Most of the pathogenesis-related genes were differentially activated after F. veticillioides infection, depending on the resistance level of the maize genotypes. In kernels of the resistant line, the defense-related genes assayed were transcribed at high levels before infection and provided basic defense against the fungus. In the susceptible kernels, the defense-related genes were induced from a basal level, responding specifically to pathogen infection. The qRT-PCR in infected silks showed that PR1, PR5, PRm6 and thaumatin genes had lower expression ratios in the resistant line compared to the susceptible one.

Bleomycin genotoxicity and amifostine (WR-2721) cell protection in normal leukocytes vs. K562 tumoral cells.

Recent advances in chemotherapy have focused on the benefit of high dose regimens, increasing the dose intensity of conventional chemotherapy. However, unacceptable cytotoxicity and genotoxicity on normal cells often impairs the proper management of patients. Phosphoaminothiol WR-1065, the active metabolite of amifostine, appears to protect normal cells and tissues against cytotoxic exposure to radiation or chemotherapeutic agents. Nevertheless, there is disagreement in findings on amifostine protection against bleomycin-induced severe side effects which have suggested that amifostine effectiveness against bleomycin-induced genotoxicity in normal leukocytes and tumour line cells K562 be studied. DNA damage was detected by single cell gel electrophoresis (or Comet) assay, a technique able to detect DNA strand breaks, alkali-labile sites and incomplete excision repair events in individual cells and which appears to be an ideal tool for assessing variability in response of different cell types in vitro. WR-2721 appears to selectively protect healthy leukocytes but not K562 tumoral cells. On the other hand, data on the inter- and intra-individual sensitivity to bleomycin and amifostine suggest that individual metabolic/genetic differences and other factors relating to lifestyle may be responsible for response variability. Application of the Comet assay in appropriate clinical settings to test the sensitivity of patients when undergoing chemotherapy appears possible.