Four glutathione S-transferase (GST) genes, NbGSTU1, NbGSTU2, NbGSTU3, and NbGSTF1, were amplified from cDNA of Nicotiana benthamiana leaves infected with Colletotrichum destructivum using primers based on conserved regions of N. tabacum GST sequences. Expression of NbGSTU1 and NbGSTU3 increased progressively during infection by either C. destructivum or Colletotrichum orbiculare, except for a slight decrease by NbGSTU1 late in the infection, whereas NbGSTU2 and NbGSTF1 expression remained relatively constant. Each of the four genes was cloned into a PVX vector for virus-induced gene silencing, and reduced expression of the four genes was detected by RT-PCR. A statistically significant increase in susceptibility of N. benthamiana to infection following gene silencing was found only for NbGSTU1-silenced plants, which had 130% more lesions and 67% more colonization by C. orbiculare compared with control plants. These results demonstrate that the different GST genes respond in different ways to fungal infection, and at least one plant GST gene has an important role in disease development.

The ability of nonpathogenic isolates of Fusarium oxysporum (np Fo ) to induce systemic resistance and defence responses against subsequent challenge with a pathogenic strain of F. oxysporum f. sp. asparagi ( Foa ) was examined in Asparagus officinalis . In a split‐root experiment, roots inoculated with np Fo exhibited a hypersensitive response and those subsequently inoculated with Foa displayed resistance. Induction of systemic resistance in np Fo ‐treated plants led to significantly fewer necrotic lesions ( P = 0·05) and reduced Foa disease severity compared with plants not treated with np Fo . In hyphal‐sandwich root inoculation experiments, activities of peroxidase and phenylalanine ammonia‐lyase and lignin content were higher in np Fo ‐treated plants and increased more rapidly than in np Fo ‐untreated plants after Foa inoculation. Antifungal activity (inhibition of fungal spore germination and germ‐tube growth) from exudates of roots inoculated with Foa were observed for np Fo ‐treated plants but not for np Fo ‐untreated plants. Thus, isolates of np Fo may function as inducers of systemic acquired resistance (SAR) and defence responses against Foa invasion in A. officinalis .

Mango (Mangifera indica L.) is an economically significant fruit crop in provinces of southern China including Hainan, Yunnan, Sichuan, Guizhou, Guangdong and Fujian. The objective of this study was to examine the diversity of Colletotrichum species infecting mango cultivars in major growing areas in China, using morphological and molecular techniques together with pathogenicity tests on detached leaves and fruits. Over 200 Colletotrichum isolates were obtained across all mango orchards investigated, and 128 of them were selected for sequencing and analyses of actin (ACT), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer (ITS) region, β-tubulin (TUB2) genomic regions. Our results showed that the most common fungal isolates associated with mango in southern China involved 13 species: Colletotrichum asianum, C. cliviicola, C. cordylinicola, C. endophytica, C. fructicola, C. gigasporum, C. gloeosporioides, C. karstii, C. liaoningense, C. musae, C. scovillei, C. siamense and C. tropicale. The dominant species were C. asianum and C. siamense each accounting for 30%, and C. fructicola for 25%. Only C. asianum, C. fructicola, C. scovillei and C. siamense have previously been reported on mango, while the other nine Colletotrichum species listed above were first reports associated with mango in China. From this study, five Colletotrichum species, namely C. cordylinicola, C. endophytica, C. gigasporum, C. liaoningense and C. musae were the first report on mango worldwide. Pathogenicity tests revealed that all 13 species caused symptoms on artificially wounded mango fruit and leaves (cv. Tainong). There was no obvious relationship between aggressiveness and the geographic origin of the isolates. These findings will help in mango disease management and future disease resistance breeding.

Microdochium nivale (Fr.) Samuels & Hallett and Microdochium majus (Wollenw.) Glynn & S.G. Edwards are sister species that cause diseases on grasses and cereals at low temperatures. The DNA sequences of RPB2 (RNA polymerase II), β-tubulin, EF-1α (elongation factor), and ITS (rDNA internal transcribed spacer) from these groups were analysed to compare the extent of differences between these species, among isolates from Europe compared with those from North America, and among isolates of M. nivale originally collected from Agrostis spp. compared with isolates from wheat (Triticum aestivum). All of the regions studied except for ITS resolved M. nivale and M. majus isolates into separate clades. The RPB2 sequences also resolved both the North American and European M. majus isolates and M. nivale isolates from either turfgrasses or wheat into separate clades. These results support the recent elevation of M. nivale and M.majus to sister species and also provide some support for the assertion that there may be host-specific differences among M. nivale, which has a wider host range than M. majus.

Colletotrichum higginsianum is a hemibiotrophic ascomycetous fungus that causes economically important anthracnose diseases on numerous monocot and dicot crops worldwide. As a model pathosystem, the Colletotrichum–Arabidopsis interaction has the significant advantage that both organisms can be manipulated genetically. The goal of this review is to provide an overview of the system and to point out recent significant studies that update our understanding of the pathogenesis of C. higginsianum and resistance mechanisms of Arabidopsis against this hemibiotrophic fungus. The genome sequence of C. higginsianum has provided insights into how genome structure and pathogen genetic variability has been shaped by transposable elements, and allows systematic approaches to longstanding areas of investigation, including infection structure differentiation and fungal–plant interactions. The Arabidopsis-Colletotrichum pathosystem provides an integrated system, with extensive information on the host plant and availability of genomes for both partners, to illustrate many of the important concepts governing fungal–plant interactions, and to serve as an excellent starting point for broad perspectives into issues in plant pathology.