A screening method to detect BYDV‐PAV resistance in cereals under glasshouse conditions

Abstract

A reliable method was developed to screen cereal crops for BYDV‐PAV resistance in glasshouse experiments. This also entailed the evaluation of traits associated with Barley yellow dwarf virus (BYDV) infection such as leaf discolouration, reduction in growth, biomass and yield traits, and percentage of virus‐infected plants, using enzyme‐linked immunosorbent assay (ELISA) and tissue blot immunoassay (TBIA). Four glasshouse experiments were conducted with eight wheat, barley and oat varieties inoculated with BYDV‐PAV at the 2‐leaf stage, using different numbers of viruliferous aphids and different inoculation periods and temperatures. Inoculation with 5–10 viruliferous aphids per plant for 4 days led to a high percentage of infection in susceptible varieties, indicating that this is an effective BYDV screening method when selecting for resistance in cereal crops. For barley and oat, visual evaluation of symptoms is considered adequate for assessing BYDV resistance. However, for wheat it is necessary to evaluate BYDV resistance by ELISA/TBIA tests and plant biomass (at early stage) and grain number and yield (at late stage) measurements.

The Evaluation of Wheat Cultivar Resistance and Yield Loss Thresholds in Response to Barley Yellow Dwarf Virus-PAV Infection

“…However, symptoms were rather severe, and greater than those on Sparta. These results again suggest that the evaluation of wheat resistance to BYDV-PAV based on symptoms is not effective and that analysis of GWS-R [7] and/or reduction in biomass [22] is necessary for a reliable evaluation of resistance. Quantifying virus titre analysis by using RT-qPCR can also be used to enhance the efficiency of resistance evaluation of wheat cultivars to BYDV-PAV and PAS [5].…”

Genomic regions on chromosome 5H containing a novel QTL conferring barley yellow dwarf virus-PAV (BYDV-PAV) tolerance in barley

“…Considering barley yellow dwarf as a severe and proliferated plant disease in many regions of the world, it will be of high significance to identify high quality markers associated with novel genes conferring BYD resistance/ tolerance. However, evaluation of plant resistance to BYDV is complicated by numerous factors such as aphid specificity and availability, field climate which affects aphid transmission and propagation, and plant growth stage when aphid feeding occurs 3,32–35 . It is therefore necessary to screen for BYD resistance under multiple environments.…”

“…Although the plants in Tasmanian trials were artificially inoculated, higher degree of disease severity and disease incidence was observed in Western Australia, where two additional QTL were detected. As increased number of aphids was associated with higher rate of infection 3 , more aphids were used in TAS trials to ensure the infection of all the lines. Furthermore, the WA trial scored severer overall symptom and the correlation values of TAS and WA trials being not very high, which indicates different genes operative under different environments.…”

“…Three replicates were applied. For BYDV-PAV treatment, each line was inoculated with viruliferous aphids restricted in a breathable mesh container clipped on leaves to avoid aphids escape 3 . One week after inoculation, the clips were removed, and insecticides were sprayed to kill aphids.…”

“…The phloem-limited virus is not mechanically or seed transmissible but is transmitted by one or more aphid species in a persistent, circulative manner 2 . Infection of BYDV causes many agronomical, biochemical, physiological and ultrastructural changes 3,4 , leading to major symptoms of leaf yellowing, stunted plant growth, which are known as barley yellow dwarf (BYD) disease 5,6 . Consequently, significant yield losses or reduction of yield components with oats showing the highest susceptibility of crop plants have been reported 7,8 .…”