Jsc. Clark et Ptn. Spencerphillips, RESISTANCE TO PERONOSPORA-VICIAE EXPRESSED AS DIFFERENTIAL COLONY GROWTH IN 2 CULTIVARS OF PISUM-SATIVUM, Plant Pathology, 43(1), 1994, pp. 56-64
Peronospora viciae sporulated frequently following localized inoculati
on of leaflets of Pisum sativum cv. Krupp Pelushka but rarely on cv. E
arly Onward (60 and < 1% of plants respectively). Similar results were
obtained following inoculation of seedling shoot apices. The proporti
ons of sporangia that germinated, formed appressoria, invaded via stom
ata or cuticle, and established colonies, were similar on leaflets of
both cultivars. After 2 days, total hyphal lengths of most colonies we
re greater than 100 mu m (94% in Krupp Pelushka, 64% in Early Onward),
but in Krupp Pelushka there were five times as many haustoria per uni
t length of hypha. Subsequently, only occasional colonies in Early Onw
ard grew to the same extent as in Krupp Pelushka, with 8% and 88% resp
ectively attaining lengths > 800 mu m after 4 days. Reduced growth of
hyphae in Early Onward was associated with increased frequency of host
cells stained by trypan blue.