H. Paul et al., USE OF ZOOSPORES OF POLYMYXA-BETAE IN SCREENING BEET SEEDLINGS FOR RESISTANCE TO BEET NECROTIC YELLOW VEIN VIRUS, Netherlands journal of plant pathology, 99, 1993, pp. 151-160
A system to culture viruliferous Polymyxa betae and to produce zoospor
es is described. The zoospores were used for inoculation of beet seedl
ings, grown in nutrient solution, in tests for resistance to beet necr
otic yellow vein virus (BNYVV). On most occasions in a time course exp
eriment, and with various zoospore cultures, the partially resistant c
ultivar Rima and the accession Holly-1-4 had virus concentrations simi
lar to the susceptible cultivar Regina, but the virus concentration in
Beta vulgaris ssp. maritima accession WB42 was significantly lower (P
< 0.05). 'Regina' could be distinguished from various resistant acces
sions by a significantly higher virus concentration (P < 0.05) shortly
after inoculation, or after transplanting the seedlings from the nutr
ient solution into sand. Results of screening for resistance to BNYVV,
using zoospores for inoculation, did not correspond with results of a
test in which infested soil was used. Tests in which seedlings are gr
own in nutrient solution and inoculated with zoospores are suitable fo
r the detection of accessions with a high level of resistance to BNYVV
. To obtain virus infection in all plants, the optimal density of the
zoospore suspension should first be determined and plants should be as
sayed shortly after inoculation.