The effects of barley yellow dwarf virus and powdery mildew in oats and barley with single and dual infections

Abstract

S U M M A R YPrior infection by barley yellow dwarf virus (BYDV) initially suppressed, then subsequently enhanced the amount of powdery mildew (Ervsiphe graminis DC ex Merat) on oat cv. Maldwyn and barley cv. Proctor. Carbendazim applied as a spray decreased mildew on virus-free and BYDV-infected plants, but had no effect on virus symptoms. In oats, both mildew and BYDV infection significantly increased the number of heads but decreased the number of grains per head. Mildew infection of BYDV-infected plants had no further effect. BYDV significantly increased the 1000 grain weight of oats, but mildew caused no significant alteration in grain weights of either virus-free or BYDV-infected plants. Both mildew and BYDV reduced the yield of oats, but mildew infection of BYDV-infected plants caused no further significant alteration. Percentage crude protein was increased in grain from both BYDVinfected and imildew-infected oats, but significantly only in BYDV-infected plants.In barley, the number of spikelets on the main shoot, the number of heads and the number of grains per head were all significantly reduced by BYDV but not by mildew. Mildew infection of BYDV-infected plants had no further effect. Both BYDV and mildew significantly reduced the 1000 grain weight of barley, but mildew infection of BYDV-infected plants caused a significant increase in 1000 grain weight compared to mildew-free, virus-infected plants. The yield of barley was significantly reduced by mildew and by BYDV, but no additional yield loss was caused by mildew infection of BYDV-infected plants. The percentage crude protein of barley was increased, but not significantly, by mildew and by BYDV.

Interactions among symbionts operate across scales to influence parasite epidemics

“…) a net positive or a net negative effect on Colletotrichum and Rhizoctonia to have a net negative effect on Colletotrichum . Vertically transmitted fungal endophytes can facilitate or suppress infection by fungal parasites via resource competition and changes in host immunity, which depends on parasite feeding strategies (Potter , ; Liu et al . ; Saikkonen et al .…”

“…1) a net positive or a net negative effect on Colletotrichum and Rhizoctonia to have a net negative effect on Colletotrichum. Vertically transmitted fungal endophytes can facilitate or suppress infection by fungal parasites via resource competition and changes in host immunity, which depends on parasite feeding strategies (Potter 1980(Potter , 1982Liu et al 2006;Saikkonen et al 2013). Therefore, we expected the endophyte to facilitate biotrophs such as Puccinia, and to inhibit hemibiotrophs and necrotrophs such as Colletotrichum and Rhizoctonia.…”

Somaclonal variation — a novel source of variability from cell cultures for plant improvement

“…comm.). There are many examples where prior infection of a plant with a virus results in an enhanced susceptibility to a fungal disease (Latch and Potter 1977;Potter 1980). For example, infection with maize dwarf mosaic virus renders wheat and maize more susceptible to root and stalk rotting fungi, maize and sorghum more susceptible to Helrninthosporium maydis, and wheat more susceptible to Puccinia recondita.…”

Genetic modification of agronomic traits in fruit crops

“…• cytokinin and auxin habituation (Meins and Binns 1977) • chilling resistance (Dix and Street 1976) • changing susceptibility to fungal attack (Potter 1980) • susceptibility to certain pathogens, due maybe to virus elimination during regeneration, which can also alter plant habit.…”