Rhizoctonia cerealis, the causal agent of sharp eyespot on wheat, was not considered to be an important pathogen for many years. Recently, the disease has become endemic in many countries except for South America. The disease has created a new threat to world wheat production because the damage of wheat sharp eyespot has become increasingly severe. In this paper, previous studies on this pathogen, including the disease geographical distribution, pathogen identification, life cycle, symptoms, favourable environmental conditions, effects on wheat yield and control strategy, are reviewed. Such information will be helpful in management of sharp eyespot.

The Ccz1-Mon1 protein complex, the guanine nucleotide exchange factor (GEF) of the late endosomal Rab7 homolog Ypt7, is required for the late step of multiple vacuole delivery pathways, such as cytoplasm-to-vacuole targeting (Cvt) pathway and autophagy processes. Here, we identified and characterized the yeast Mon1 homolog in Fusarium graminearum, named FgMon1. FgMON1 encodes a trafficking protein and is well conserved in filamentous fungi. Targeted gene deletion showed that the ∆Fgmon1 mutant was defective in vegetative growth, asexual/sexual development, conidial germination and morphology, plant infection and deoxynivalenol production. Cytological examination revealed that the ∆Fgmon1 mutant was also defective in vacuole fusion and autophagy, and delayed in endocytosis. Yeast two hybrid and in vitro GST-pull down assays approved that FgMon1 physically interacts with a Rab GTPase FgRab7 which is also important for the development, infection, membrane fusion and autophagy in F. graminearum. FgMon1 likely acts as a GEF of FgRab7 and constitutively activated FgRab7 was able to rescue the defects of the ∆Fgmon1 mutant. In summary, our study provides evidences that FgMon1 and FgRab7 are critical components that modulate vesicle trafficking, endocytosis and autophagy, and thereby affect the development, plant infection and DON production of F. graminearum.

Fusarium Ear Blight is a destructive fungal disease of cereals including wheat and can contaminate the crop with various trichothecene mycotoxins. This investigation has produced a new β-glucuronidase (GUS) reporter strain that facilitates the quick and easy assessment of plant infection. The constitutively expressed gpdA:GUS strain of Fusarium graminearum was used to quantify the overall colonisation pattern. Histochemical and biochemical approaches confirmed, in susceptible wheat ear infections, the presence of a substantial phase of symptomless fungal growth. Separate analyses demonstrated that there was a reduction in the quantity of physiologically active hyphae as the wheat ear infection proceeded. A simplified linear system of rachis infection was then utilised to evaluate the expression of several TRI genes by RT-qPCR. Fungal gene expression at the advancing front of symptomless infection was compared with the origin of infection in the rachis. This revealed that TRI gene expression was maximal at the advancing front and supports the hypothesis that the mycotoxin deoxynivalenol plays a role in inhibiting plant defences in advance of the invading intercellular hyphae. This study has also demonstrated that there are transcriptional differences between the various phases of fungal infection and that these differences are maintained as the infection proceeds.

Fusarium crown rot of wheat has become more prevalent in China. To investigate the phylogenetic structure of Fusarium causing wheat crown rot in China, wheat basal stems with symptoms of the disease were collected from 2009 to 2013 in Jiangsu, Anhui, Henan, Hebei, and Shandong provinces. In total, 175 Fusarium isolates were collected and their mycotoxin chemotypes and distribution were identified. Among the 175 isolates, 123 were Fusarium asiaticum; 95 of these were the chemotype 3-acetyl-deoxynivalenol (3-AcDON) and 28 were nivalenol (NIV). Thirty-seven isolates belonged to F. graminearum, which were all 15-AcDON. Smaller numbers of isolates consisted of F. acuminatum, F. pseudograminearum, and F. avenaceum. The virulence of F. asiaticum and F. graminearum isolates on wheat crowns and heads was comparable. The virulence of isolates of the DON and NIV chemotype were statistically similar, but DON tended to be more aggressive. The DON concentrations in grains from wheat heads inoculated with isolates causing either Fusarium head blight or crown rot were similar. In the five provinces, F. asiaticum of the 3-AcDON chemotype was the predominant pathogen causing crown rot, followed by F. graminearum. Recent changes in causal Fusarium species, chemotypes, and distribution in China are discussed.