Las is transmitted by the Asian citrus psyllid (ACP) Diaphorina citri (Hemiptera: Psyllidae) in a persistent manner, but its interactions with the psyllid vector, particularly at the organ and cellular levels, are poorly understood. We have tested several fluorescence in situ hybridization

(FISH) protocols and three nucleic acid probes for the localization of Las in haemolymph smears and dissected organs of ACP adults that fed on Las-infected plants in the field or laboratory and in sections from Las-infected citrus leaves. Las was detected by FISH and confocal laser scanning microscopy in the filter chamber, midgut, Malpighian tubules, haemolymph, salivary glands, Opaganib clinical trial ovaries and in muscle and fat tissues of ACP that acquired Las from infected plants, as well as in the phloem of infected citrus leaves. Las appeared

as pleiomorphic bodies or short thin rods that were much more dispersed and individually distinct in citrus leaf phloem and in ACP haemolymph, but more densely aggregated in cells of the salivary glands and other ACP organs and tissues. Our results provide the first in situ demonstration of Las infection in various psyllid organs and tissues and show the near-systemic infection of ACP by Las. “
“A total of 241 isolates of Phytophthora infestans were collected in 1997, 2006 and 2007 in eight European countries and characterized with molecular markers (simple sequence repeats, SSR genotypes) and phenotypic traits selleck inhibitor such as sensitivity to fungicides, mating type and aggressiveness. The mating type distribution changed from mainly A1 in 1997 to a majority of A2 in 2007. No resistant isolates were detected for

fluazinam and mandipropamid, whereas the proportion selleck compound of isolates resistant to mefenoxam (MFX) was high and increased over the years. There was no genetic link between mating type and MFX resistance. Aggressiveness (product between lesion expansion and sporulation capacity) was slightly higher for MFX-resistant compared to sensitive isolates and for isolates collected later compared to earlier in the same season. It was about equally high for A1 and A2 types, and for French isolates in 1997 and British isolates in 2007, but lower for French isolates in 2007. Six different SSR genotype families were distinguished. In 1997, populations were dominated by genotype families I and III/IV, which significantly declined in 2007 being largely displaced by genotype families II (‘blue 13’ type) and V, which are by coincidence mainly A2 MFX resistant and A1 MFX sensitive, respectively. However, mating type and MFX resistance were genetically not linked to SSR genotypes. “
“The application of silicon (Si) reduces the intensity of diseases in several economically important crops.