The Expression of Resistance to Latent Stem Infection byDiaporthe toxicain Narrow-Leafed Lupin

Scientific information on mycotoxins and natural plant toxicants

“…Colonization of tissues below the cuticle began immediately after excision of stems from susceptible plants, but was delayed in resistant plants (Shankar et al, 1998a). Conidial germination and penetration of the cuticle are not affected by host resistance, and resistance appears to be the result of preexisting or induced resistance responses in epidermal cells below the infection site (Shankar et al, 1996).…”

“…Williamson et al (1991) developed an artificial inoculation, tissue staining and microscopic examination procedure to visualise subcuticular coralloid mycelia which are a latent infection structure. Shankar et al (1996) standardised the inoculation and incubation procedures and was able to show that breeding lines known to be resistant or susceptible under field conditions had small or large coralloid structures, respectively. These last two studies were hampered by the lack of a non-destructive glasshouse test for resistance.…”

Development of molecular markers using MFLP linked to a gene conferring resistance to Diaporthe toxica in narrow-leafed lupin (Lupinus angustifolius L.)

“…Four weeks after sowing, stems of the seedling plants were excised above the second leaf node to encourage the regeneration of two lateral branches. The axillary internode of one of the branches was sprayed to run-off with a conidial suspension (1 × 10 7 conidia per ml) of D. toxica using an artist's air brush (Williamson et al 1991;Shankar et al 1996). The other branch was protected from infection and maintained for seed production.…”

“…The inoculated branch was excised 21 days after inoculation at the base, and stored at -20°C. The epidermal layers of inoculated stem segments were peeled, and stained with alcoholic lactophenol cottton blue (Shankar et al 1996). Plants were classified as resistant or susceptible based on the size of coralloid hyphae observed under a microscope (Shankar et al 2002).…”

“…Selection for phomopsis resistance is one of the major objectives in the lupin breeding program in Western Australia. However, reliable screening for disease resistance requires staining and observing the subcuticular coralloid hyphae under a microscope (Shankar et al 1996(Shankar et al , 1998b, a process which is labour intensive and time-consuming. Shankar et al (2002) identified two dominant resistance genes against PSB in L. angustifolius by traditional genetic analysis.…”