Aphid-resistance of Oilseed Rape (Brassica napus) does not Necessarily Impede Turnip Mosaic Virus Transmission
Plant viruses improve transmission efficiency by directly and indirectly influencing vector behavior, but the impact of plant cultivars on these modifications is rarely studied. Using electropenetrography (EPG) technology, a comparative study of the effects of turnip mosaic virus (TuMV) infection on quantitative probing behaviors of the cabbage aphid (Brevicoryne brassicae) was conducted on two oilseed rape cultivars (‘Deleyou6’ and ‘Zhongshuang11’). Compared to mock-inoculated plants, cabbage aphids on infected plants increased the frequency of brief probing, cell penetration, and salivation. On the aphid-susceptible cultivar ‘Deleyou6’, in addition, aphids were more likely to acquire and vector TuMV than on resistant cultivars, as evidenced by the lengthened cell penetration time, and decreased ingestion caused by TuMV infection. TuMV also affected aphid probing behavior directly. Viruliferous aphids reduced the pathway duration, secreted more saliva, and ingested less sap than non-viruliferous aphids. In comparison with non-viruliferous aphids, viruliferous aphids started the first probe earlier, and increased brief probing and cell penetration frequencies on the aphid-resistant cultivar ‘Zhongshuang11’. Based on these observations, viruliferous aphids can inoculate TuMV more efficiently on ‘Zhongshuang11’ than on ‘Deleyou6’. Although aphid resistance and TuMV infection may influence aphid probing behavior, oilseed rape resistance to aphids does not impede TuMV transmission effectively.