Control of barley yellow dwarf virus (BYDV) in oat and wheat and identification of a RAPD marker associated with BYDV tolerance in oat

Abstract

Populations of F\sb2 and F\sb3 plants from intraspecific spring oat (Avena sativa L.) crosses were grown in the greenhouse using a modified single-seed descent method with 100 plants per 15 cm pot. Subpopulations were inoculated with the BYDV-PAV-IL strain (1) in the F\sb2 generations only, and (2) in the F\sb2 and F\sb3 generations, using viruliferous aphids (Rhopalosiphum padi L.). These subpopulations were compared to uninoculated subpopulations. Inoculation did not increase the frequency of BYDV tolerant genotypes in the four crosses studied.The transmission characteristics of wingless (nymphs and apterous adults) viruliferous R. padi after access to oat treated with different rates of imidacloprid, a seed-treatment insecticide, were compared. After access to treated plants, aphid fecundity was reduced, aphids walked and fed atypically, and often abandoned the host plant. Aphids transmitted the virus to both treated and untreated plants, but the percentage of infected insecticide-treated seedlings was half that of untreated seedlings.The control of barley yellow dwarf using imidacloprid at three rates (0.6, 1.2 and 1.8 g a.i. Kg\sp{-1}) was studied in two oat and four soft red winter wheat cultivars in six-row plots. All insecticide treatments decreased the percentage of infected plants. Compared to untreated plots, yields were increased 112% and 35% in 1992 and 1993, respectively, in treated plots of a moderately susceptible oat cultivar inoculated with viruliferous aphids carrying BYDV-PAV-IL. In insecticide-treated plots of a tolerant oat cultivar, yields increased 23% and 21% in 1992 and 1993, respectively, compared to untreated plots. Yield increases of up to 21% were observed in treated plots of a susceptible wheat cultivar inoculated with viruliferous aphids carrying BYDV-PAV-IL. For all wheat cultivars, yield was negatively correlated with the percent disease incidence, and positively correlated with test weight and the calculated number of seeds tiller\sp{-1}. Test weight was negatively correlated with kernel weight.A RAPD marker associated with a gene for BYDV tolerance was identified in neat-isogenic lines (NILs) differing in BYDV tolerance. The NILs were derived by backcrossing with the sensitive cultivar Clintland 64 as recurrent parent to tolerant parents Ogle, IL 86-5698, IL 86-6404, and IL 86-1156 as donor parents. A polymorphic band is present in the donor parents and most BYDV tolerant NILs, but absent in the recurrent parent. The marker is associated with a gene for BYDV tolerance in NILs of IL 86-5698 x Clintland 64 and of IL 86-1156 x Clintland 64. The marker is not associated with BYDV tolerance in the two groups of NILs derived from backcross involving Ogle x Clintland 64 and IL 86-6404 x Clintland 64.U of I OnlyETDs are only available to UIUC Users without author permissio