Articles
VARIATION IN PATHOGENICITY, MORPHOLOGY AND CONIDIAL AGGLUTINATION OF FUSARIUM OXYSPORUM F.SP. NARCISSI AND RESISTANCE TO BASAL ROT IN NARCISSUS
The highly virulent isolates were not found to be those isolated from highly susceptible cultivars as has previously been suggested.
Some Narcissus species are resistant to all virulence types.
Plant breeders should be aware of the existence of a range of virulence types within F. oxysporum f.sp. narcissi and that resistance breaking isolates may evolve.
Avirulent isolates and those with low virulence showed greater agglutination of microconidia in the presence of Narcissus pseudonarcissus lectin (NPL) than those classified as of moderate or high virulence.
Auto-agglutination of erythrocytes by bulb extracts was found to be caused by high levels of lectin in the bulbs.
This agglutination could be removed by the addition of mannose.
The results of differential cultivar agglutination of erythrocytes suggested that lectin levels may be related to disease resistance.
Extracts of Narcissus species previously shown to be resistant to basal rot such as N. jonquilla and N. broussonetii diluted to 1:1024, agglutinated erythrocytes after 30 seconds.
Agglutination by the susceptible cultivar Golden Harvest and N. pseudonarcissus occurred only up to a dilution of 1:64. Further investigations are planned to include a wider range of cultivars and species, to examine both the agglutination levels and isolectin patterns and link these to known disease resistance scores.
This type of test may provide opportunities for rapid screening of new breeding material for disease resistance and will be tested on progeny from species/cultivar crosses.