Verticillium longisporum, the invisible threat to oilseed rape and other brassicaceous plant hosts.

INTRODUCTION: The causal agents of Verticillium wilts are globally distributed pathogens that cause significant crop losses every year. Most Verticillium wilts are caused by V. dahliae, which is pathogenic on a broad range of plant hosts, whereas other pathogenic Verticillium species have more restricted host ranges. In contrast, V. longisporum appears to prefer brassicaceous plants and poses an increasing problem to oilseed rape production. TAXONOMY: Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Subclass Hypocreomycetida; Family Plectosphaerellaceae; genus Verticillium. DISEASE SYMPTOMS: Dark unilateral stripes appear on the stems of apparently healthy looking oilseed rape plants at the end of the growing season. Microsclerotia are subsequently formed in the stem cortex beneath the epidermis. GENOME: Verticillium longisporum is the only non-haploid species in the Verticillium genus, as it is an amphidiploid hybrid that carries almost twice as much genetic material as the other Verticillium species as a result of interspecific hybridization. DISEASE MANAGEMENT: There is no effective fungicide treatment to control Verticillium diseases, and resistance breeding is the preferred strategy for disease management. However, only a few Verticillium wilt resistance genes have been identified, and monogenic resistance against V. longisporum has not yet been found. Quantitative resistance exists mainly in the Brassica C-genome of parental cabbage lines and may be introgressed in oilseed rape breeding lines. COMMON NAME: Oilseed rape colonized by V. longisporum does not develop wilting symptoms, and therefore the common name of Verticillium wilt is unsuitable for this crop. Therefore, we propose 'Verticillium stem striping' as the common name for Verticillium infections of oilseed rape.

Zoosporicidal metabolites from an endophytic fungus Cryptosporiopsis sp. of Zanthoxylum leprieurii.

Two polyketides, cryptosporiopsin A (1) and hydroxypropan-2',3'-diol orsellinate (3), and a natural cyclic pentapeptide (4), together with two known compounds were isolated from the culture of Cryptosporiopsis sp., an endophytic fungus from leaves and branches of Zanthoxylum leprieurii (Rutaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic and spectrometric data. Cryptosporiopsin A and the other metabolites exhibited motility inhibitory and lytic activities against zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 10-25µg/mL. In addition, the isolated compounds displayed potent inhibitory activity against mycelial growth of two other peronosporomycete phytopathogens, Pythium ultimum, Aphanomyces cochlioides and a basidiomycetous fungus Rhizoctonia solani. Weak cytotoxic activity on brine shrimp larvae was observed.