This study combined the micro-cross-section cultural system with in vitro mutagenesis induced by ethyl methanesulphonate (EMS) to screen for fusarium wilt-resistant lines of Brazil banana (Musa spp., AAA). The results indicated that the optimum EMS concentration and duration for the treatment of micro-cross-sections cut from the pseudostem of tissue-cultured plantlet were 300 mM and 60 min, respectively. Under the optimal treatment, an average of 2AE2 regenerated shoots were produced from each explant. One hundred regenerated plantlets were used for screening for fusarium wilt-resistant lines by the early screening technique. The initial disease symptom -yellowing in lower leaves of susceptible plantlets -was observed 2 weeks after inoculation. After 2 months, only six plants survived -the putative fusarium wilt-resistant lines. The fusarium wilt pathogen Fusarium oxysporum f. sp. cubense race 4, was identified in the preliminary test field by a SCAR marker technique. Of the six putative resistant lines, five survived the preliminary field test. The regenerated plantlets from these five fusarium wilt-resistant lines were subjected to early screening again, where they showed markedly reduced disease incidences compared with regenerated plantlets of Brazil banana (control). It was concluded that EMS-induced mutation of banana through the micro-cross-section cultural system is potentially useful for banana improvement.

Fusarium wilt caused by Fusarium commune is a major limiting factor for Chinese water chestnut (Eleocharis dulcis) production in China. A SYBR Green I real‐time quantitative polymerase chain reaction (qPCR) assay was developed based on the mitochondrial small subunit rDNA of F. commune. Assay specificity of the FO1/FO2 primer set was tested on 41 fungal isolates, and only a single PCR band of c. 178 bp from F. commune was amplified. The detection limits of the assay were 1 fg μL−1 pure F. commune genomic DNA, 1 pg μL−1 F. commune genomic DNA mixed with host plant genomic DNA (0·5 ng μL−1), and 1000 conidia/g soil (artificially inoculated). The amount of F. commune DNA in stem tissues detected by qPCR was significantly correlated with the disease severity (DS) ratings; however, the qPCR assay showed no significant positive correlation between spore densities in soil of different fusarium wilt DS groupings and the DS ratings. The qPCR assay was further applied to 76 soil samples collected from commercial fields of E. dulcis during the 2011 and 2012 growing seasons. The spore density of F. commune detected was positively correlated with disease index in the 2012 growing season but not in 2011. The qPCR method can be used for rapid and specific detection of F. commune in plant and soil samples, which will facilitate monitoring of the pathogen and improvement of disease management.