Summary

“Fusarium yellows” in ginger is caused by Fusarium oxysporum f.sp. zingiberi (Foz). This fungal pathogen is soil borne, attacking ginger roots and rhizomes leading to rhizome decay and disruption of the plant’s vascular system with the first visible symptoms in the field being the characteristic yellowing of the pseudostems. Spread of this soilborne fungus is via soil, including machinery carrying soil, or by infected rhizomes. The infected rhizomes lead to carry-over and build-up of inoculum from one season to the next and allow spread into otherwise non-infested land. Thus, the use of clean disease-free rhizome as planting material is critical in halting the progress of this disease thus, knowing that material is disease free is vital.

Fusarium oxysporum, as a species, contains many different forms that include up to 200 host specific pathogens, attacking a wide range of crop plant species such as Fusarium oxysporum f.sp. cubense on banana, Fusarium oxysporum f.sp. vasinfectum on cotton and Fusarium oxysporum f.sp. dianthi on carnation. Fusarium oxysporum can also exist as endophytes, in the roots and other tissues of plants where they are present without causing any symptoms; some of these endophytes have been shown to be beneficial protecting the host plants from attack by pathogenic strains (Forsyth et al. 2006; Albouvette et al. 1986 ). In developing a diagnostic, it is important to be able to distinguish the pathogenic form of Fusarium oxysporum from what may well be abundant endophytic forms.

Fusarium oxysporum is a very persistent fungus with the pathogenic strains being shown to survive in the soil for many years in the absence of the host; most likely doing so as saprophytes on plant matter in the soil or as endophytes on other plant species. Consequently, eradication of a pathogenic form once present in a field is not possible. The best control measure is avoidance and for that again knowing planting material is disease free vital. However, Fusarium oxysporum, whether as saprophyte, endophyte or pathogen, is present in most soils and in many plant species, so detection of pathogenic forms needs to be specific.

This project aims to

Confirm the profile of genes SIX 7, SIX 9, SIX 10 and SIX 12 in Fusarium oxysporum f.sp. zingiberi (Foz) in endophytic isolates from ginger and plants in ginger rotations
Confirm the profile of genes SIX 7, SIX 9, SIX 10 and SIX 12 in different fusarium strains
Refine the UQ Foz primer as appropriate with the findings from the endophytic isolate sequencing

To test the UQ Foz primer, validate its efficacy in identifying Fusarium oxysporum f.sp. zingiberi in field samples of ginger and develop protocols for its effective use (i.e. ginger rhizome DNA extraction).

Program

Ginger

Research Organisation

The University of Queensland

Objective Summary

This project aims to

Confirm the profile of genes SIX 7, SIX 9, SIX 10 and SIX 12 in Fusarium oxysporum f.sp. zingiberi (Foz) and in endophytic isolates sampled from ginger and plants in ginger rotations
• Confirm the profile of genes SIX 7, SIX 9, SIX 10 and SIX 12 in different fusarium strains
• Refine the UQ Foz primer as appropriate with the findings from the Foz isolate sequencing

To test the UQ Foz primer, validate its efficacy in identifying Fusarium oxysporum f.sp. zingiberi in field samples of ginger and develop protocols for its effective use (i.e. ginger rhizome DNA extraction).