Pathogenicity of Hendersonia salsolae on Salsola kali ssp. ruthenica

A pathogen identified,as Hendersonia salsolae Moesz was isolated from foliar and stem lesions on Russian thistle [Salsola kali ssp.ruthenica (Iljin)Soó] seedlings collected in Szarkás,Hungary in 1996. Based on our field surveys and completed pathogenicity tests,it was established that this fungus is patho- genic on Salsola kali ssp.ruthenica.This is the first report about pathogenicity of H.salsolae and satis- faction of Koch 's postulates

Reappearance of bacterial leaf and flower spot on Zinnia elegans caused by Xanthomonas campestris pv. zinniae in Europe

During the years 2006 and 2007, serious outbreaks of bacterial leaf and flower spot disease were observed on zinnia ( Zinnia elegans Jaqc. cv. Mondo and Capricio) plants grown in several parks in Budapest, Hungary. Five strains of Xanthomonas campestris pv. zinniae isolated from diseased zinnia plants were identified based on morphological, physiological, biochemical and pathogenicity tests, as well as sequence analysis of the bacterial 16S–23S rDNA spacer region

Heat shock‐induced enhanced susceptibility of barley to Bipolaris sorokiniana is associated with elevated ROS production and plant defence‐related gene expression

Heat stress alters plant defence responses to pathogens. Short-term heat shock promotes infections by biotrophic pathogens. However, little is known about how heat shock affects infection by hemibiotrophic pathogens like Bipolaris sorokiniana (teleomorph: Cochliobolus sativus). We assessed the effect of heat shock in B. sorokiniana-susceptible barley (Hordeum vulgare cv. Ingrid) by monitoring leaf spot symptoms, B. sorokiniana biomass, ROS and plant defence-related gene expression following pre-exposure to heat shock. For heat shock, barley plants were kept at 49 °C for 20 s. B. sorokiniana biomass was assessed by qPCR, ROS levels determined by histochemical staining, while gene expression was assayed by RT-qPCR. Heat shock suppressed defence responses of barley to B. sorokiniana, resulting in more severe necrotic symptoms and increased fungal biomass, as compared to untreated plants. Heat shock-induced increased susceptibility was accompanied by significant increases in ROS (superoxide, H2O2). Transient expression of plant defence-related antioxidant genes and a barley programmed cell death inhibitor (HvBI-1) were induced in response to heat shock. However, heat shock followed by B. sorokiniana infection caused further transient increases in expression of HvSOD and HvBI-1 correlated with enhanced susceptibility. Expression of the HvPR-1b gene encoding pathogenesis-related protein-1b increased several fold 24 h after B. sorokiniana infection, however, heat shock further increased transcript levels along with enhanced susceptibility. Heat shock induces enhanced susceptibility of barley to B. sorokiniana, associated with elevated ROS levels and expression of plant defence-related genes encoding antioxidants, a cell death inhibitor, and PR-1b. Our results may contribute to elucidating the influence of heat shock on barley defence responses to hemibiotrophic pathogens