The results of the study suggest that a high risk for selection of QoI-resistant strains exists in crops heavily treated with QoIs, in spite of the widespread occurrence of the cytb intron in B. cinerea populations. The developed real-time TaqMan PCR constitutes a powerful tool to streamline detection of the mutation by reducing pre- and post-amplification manipulations, and can be used for rapid screening and quantification of QoI resistance.

This study was conducted primarily to investigate the presence and frequency distribution of the transposable elements Boty and Flipper in populations of the necrotroph plant pathogen Botrytis cinerea in Greece. In total, 334 isolates were collected from diseased grape, strawberry, tomato, cucumber, kiwifruit, and apple fruit during 2009. The presence of the two transposable elements was based on polymerase chain reaction detection. Results showed that all the sampled hosts occurred in sympatry, with four possible different genotypes (transposa type carrying both transposable elements, Boty type carrying only the Boty element, Flipper type carrying only the Flipper element, and vacuma type carrying neither transposable element). Marked differences in genotype frequencies among populations were observed. In tomato, cucumber, grape, and strawberry, transposa isolates carrying both elements were predominant in the populations whereas, in kiwifruit and apple fruit populations, the vacuma isolates were prevailing. Furthermore, in kiwi and apple fruit populations, high frequencies of Flipper-type isolates were observed. In an attempt to explain the observed predominance of vacuma isolates in kiwifruit populations, the mycelial growth rate of a set of vacuma isolates was compared with the mycelial growth rate of a set of transposa isolates at three different temperatures (0, 10, and 20°C). The same set of isolates was used to compare pathogenicity of isolates on wound-inoculated kiwifruit incubated at two different temperatures (0 and 20°C), in terms of disease incidence and disease severity. In addition, the selected isolates were used to compare their ability in causing latent infections on kiwifruit in the field. The results showed that vacuma and transposa isolates had similar mycelial growth rates at the limiting temperatures of 0 and 10°C, while vacuma isolates grew faster at the optimum temperature of 20°C. Similarly, there was no significant difference regarding pathogenicity on kiwifruit between transposa and vacuma isolates. However, artificial inoculations conducted on blossoms in the field showed that vacuma isolates caused significantly higher incidence of latent infections.

No abstract

Improved in vitro clonal propagation methods are valuable tools for nurseries and growers, and are essential for manipulation and improvement of tree fruit germplasm using the tools and techniques of biotechnology. We have developed a rapid shoot multiplication procedure for clonal propagation of apple, Malus ×domestica cv. Gale Gala and pear, Pyrus communis L. cv. Bartlett. Rapid clonal multiplication was achieved after the following series of steps: pre-conditioning of micropropagated shoots, sectioning pre-treated stems into thin slices, placing slices onto shoot induction medium and incubating directly under cool-white fluorescent lights or after a brief dark incubation. Multiple induction of shoots recovered from stem slice explants within three weeks of culture. A maximum of 37% of cultured apple stem slices, and 97% of pear stem slices, showed induction of shoots. More shoots were recovered on phytagel solidified shoot induction medium than on agar. Cultured stem slices of both apple and pear showed maximum recovery of shoots from shoot induction medium supplemented with thidiazuron (TDZ) compared to medium supplemented with BAP and kinetin. Under ideal conditions, pear stems generated four times the shoots as the same quantity or length of apple shoots. Micropropagated shoots were rooted and transferred to the greenhouse and field nursery for further evaluation. Chemical names used: N-phenyl-N′-1,2,3-thidiazol-5-ylurea (thidiazuron or TDZ); 6-benzylaminopurine (BAP).