Differences in Frequency of Transposable Elements Presence in Botrytis cinerea Populations from Several Hosts in Greece

Abstract

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.

Botrytis cinerea in raspberry in Serbia II: Growth rate and virulence of isolates

“…Furthermore, there was no correlation in isolate virulence to different hosts, which supports the idea that hosts may shape the pathogen's population structure (Fournier & Giraud, 2008). This finding confirmed the importance of knowing the pathogen population structure on each attacked host for developing an effective control strategy (Samuel et al, 2012). However, further research is needed to improve our understanding of the genetic structure of the pathogen using more powerful molecular techniques.…”

“…The difference between the highest and lowest growth rates was 16.1 mm/ day, suggesting different abilities of the isolates to live and spread saprotrophically, regardless of their morphological or genetic grouping. The results of Martinez et al (2003) and Samuel et al (2012) showed that the growth rate of vacuma isolates was higher than that of transposa. However, according to our results, mycelial growth rates of the isolates belonging to vacuma, transposa or boty subgroups varied similarly ( flipper group contained only two isolates and was excluded from the analysis).…”

Botrytis pseudocinerea Is a Significant Pathogen of Several Crop Plants but Susceptible to Displacement by Fungicide-Resistant B. cinerea Strains

“…These data suggest that B. pseudocinerea is the dominant blossom end rot pathogen of apple in northern Germany. In contrast, Greek Botrytis isolates from apples with storage rot belonged exclusively to B. cinerea (10). On raspberries, B. pseudocinerea was found at high frequencies only in an organic orchard (field A) but appeared to be largely absent from two intensively treated fields.…”

“…To obtain boscalid-resistant mutants of B. cinerea B05.10 and B. pseudocinerea VD110 (13) and carbendazim-resistant mutants of strain VD110, a UV treatment was performed prior to selection. For this purpose, 10 7 conidia from 12-day-old sporulating cultures were spread on yeast, Bacto peptone, and acetate (YBA) plates containing 3 mg of boscalid liter Ϫ1 or on HA plates containing 3 mg carbendazim liter Ϫ1 (16). UV irradiation was performed in a Gene Linker UV chamber (Bio-Rad Laboratories, Hercules, CA) at 120 mJ cm Ϫ2 for 18 s, which resulted in 70 to 80% lethality (nongerminating conidia on nonselective HA medium).…”

“…In particular, the presence or absence of the long terminal repeat retrotransposon Boty (7) and of the DNA transposon Flipper (8) was used to divide isolates into different transposon types, e.g., transposa (containing both transposons) and vacuma (containing no transposon). The value of this feature for genetic classification turned out to be low, but evidence has been obtained that transposa and vacuma types of B. cinerea show different adaptations to several host plants and seasonal changes in their relative frequencies (9,10). A subgroup of B. cinerea vacuma strains, called group I, was found to be clearly distinct from transposa and other vacuma strains (group II) on the basis of genetic markers and sequence data (11,12).…”