The effects of two pathotypes of pea seed-borne mosaic virus on the morphology and yield of pea

The effect of the South Australian pathotype 4 isolate (S6) of pea seed-bor ne mosaic virus (PSbMV-S6) on the yield components of pea (cv. Dundale) was compared in a glasshouse trial with that of a North American pathotype 1 i solate (PSbMV-US). Plants inoculated mechanically with PSbMV-S6 showed syst emic vein clearing, vein banding, severe mosaic, leaf distortion, abnormal tendril curling, stunting and colour break of petals, premature axillary sh oot formation, delayed flowering and pod formation, and plants matured 14 d ays late. Seed yield was reduced by 82% and the virus was transmitted to 31 % of seedlings. In comparison, PSbMV-US induced a transient, mild leaf roll ing, stunting and colour break in petals with a less noticeable effect on a xillary shoot production, and plants matured 7 days late. Seed yield was re duced by 35% and the virus was transmitted to 8% of seedlings. Infected pla nts raised from seed of plants infected with S6 were symptomless and mature d 7 days late; seed yield was reduced by 52% and 12% of their seed containe d virus. In contrast, some infected plants raised from seed of plants infec ted with PSbMV-US showed mild leaf rolling but there was no significant eff ect on yield and 7% of seed contained virus. Thus, PSbMV-S6 not only severe ly affects seed yield, but changes in plant habit and time of maturation ma y have additional deleterious effects on plant performance in field crops.