Inheritance of resistance to Plum pox virus in the progeny of the apricot cv. ‘Harlayne’

Natural resistance to Plum pox virus (PPV), the agent of sharka disease, is one of the most important traits of interest to stone fruit breeders, although few sources of resistance have been identified. One of the few apricot cultivars which does show resistance, ‘Harlayne’, was chosen for a study of the genetics of PPV resistance. It was crossed with three different cultivars, two susceptible (‘Vestar’ and ‘Strepet’) and one immune (‘Orangered’). Four different lines (since there was one reciprocal combination) were established and the F1 crosses were subsequently inoculated with the PPV-M and PPV-D strains by grafting infected buds. A woody indicator Prunus persica ‘GF 305’ was then also top-grafted onto the plants of three of these F1 populations. The observations of leaf symptoms and accompanying ELISA tests were performed over three, or in one case five, growing seasons and then hybrids were classified accordingly, as either resistant or susceptible. The resistant : susceptible ratios were calculated and compared with expected theoretical ratios using the χ2-test. The ratios of resistant to susceptible plants in the progeny derived from the four apricot crosses are compatible with the hypothesis of three dominant genes being responsible for PPV resistance, with ‘Harlayne’ being heterozygous for all three genes. However, the possibility that resistance is controlled by just two dominant genes can not be ruled out just yet

Biodegradation of Spilled Diesel Fuel in Agricultural Soil: Effect of Humates, Zeolite, and Bioaugmentation

Possible enhancement of biodegradation of petroleum hydrocarbons in agricultural soil after tank truck accident (~5000 mg/kg dry soil initial concentration) by bioaugmentation of diesel degrading Pseudomonas fluorescens strain and addition of abiotic additives (humates, zeolite) was studied in a 9-month pot experiment. The biodegradation process was followed by means of analytical parameters (hydrocarbon index expressed as content of C10–C40 aliphatic hydrocarbons, ratio pristane/C17, and total organic carbon content) and characterization of soil microbial community (content of phospholipid fatty acids (PLFA) as an indicator of living microbial biomass, respiration, and dehydrogenase activity). The concentration of petroleum hydrocarbons (C10–C40) was successfully reduced by ~60% in all 15 experiment variants. The bioaugmentation resulted in faster hydrocarbon elimination. On the contrary, the addition of humates and zeolite caused only a negligible increase in the degradation rate. These factors, however, affected significantly the amount of PLFA. The humates caused significantly faster increase of the total PLFA suggesting improvement of the soil microenvironment. Zeolite caused significantly slower increase of the total PLFA; nevertheless it aided in homogenization of the soil. Comparison of microbial activities and total PLFA revealed that only a small fraction of autochthonous microbes took part in the biodegradation which confirms that bioaugmentation was the most important treatment