Influence of heat and systemic chemicals on the multiplication of bean common mosaic virus. Thesis (Ph.D.)

Studies were carried out on effects of heat and systemic chemicals on multiplication of BCMV in Phaseolus vulgaris cv. Bountiful. Two isolates desipated as Type and NY15 strains of BCMV were obtained from the Agricultural Expt. Station, Geneva, New York (USA), and used in these studies. The isolates exhibited similar properties with regard to thermal inactivation point, dilution end point and longevity in vitro. The virus particles were flexous filaments, 745-753 nm long and 15 nm wide. Both isolates were serologically related and cross protected each other in Bountiful bean. Vigna sinensis cv. Blackeye, Phaseolus lunatus cv. Henderson's Baby Lima, Chenopodium quinoa, and C album gave differential reaction to infection by the 2 isolates. Both isolates induced discrete necrotic local lesions on inoculated primary leaves of P. vulgaris cv. Monroe. The trifoliate leaves of Monroe also gave a similar response on inoculation. This host was used for bioassay of virus multiplication. Preconditioning of bean seedlings prior to inoculation was found necessary for increased sustenance at higher temp. Heat treatment at 35 degrees Celsius (20 days) resulted in mild mosaic and low seed transmission as against that in plants treated for varied durations at 30, 37, 40, or 45 degrees Celsius. Treatment at 37 and 40 degrees Celsius induced a local lesion response in the inoculated primary leaves of Bountiful bean against Type and NY15 infections, resp. However, localization did not restrict either infection from becoming systemic. GA, oxycarboxin and carboxin delayed and significantly reduced multiplication of either strain when applied as foliar spray. Benomyl thiabendazole, and kinetin in similar trials had no effect on virus multiplication. The effect of chemicals is considered to be due to a host mediated response. (Dissertation Abstracts International) eng