01481naa a2200145 a 450000100080000000500110000800800410001910000160006024501420007626000090021830000180022749000080024552010180025377300640127116440141993-05-19       1981    bl uuuu     u00u1 u    #d1 aNAVARRO, L.  aEffect of citrus exocortis viriod (CEV) on root and callus formation by stem tissue of etrog citron (Citrus medica L.) cultured in vitro.  c1981  ap.437-439 v.1  vv.1  aTissue culture in vitro was used as a new approach to investigate the pathogenesis of the citrus exocortis viriod (CEV). Internode stem pieces of healthy and CEV-infected 'Etrog' citron (Citrus medica L.) were cultured in vitro in an adequate medium to induce root and callus. It was found taht CEV anhibited root and callus formation. The degree of inhibition increased with the age of the infection, and was related to symptom severity on the source plants. Roots were completely suppressed on internodes with severe or very severe CEV symptoms. The amount of callus was also drasticlly reduced. Healthy internodes produced 110 times more callus than internodes from plants showing very severe CEV symptoms. Very mild strains of CEV did not affect the number of internodes producing roots, but siginificantly reduced the number of roots differentiated per culture. Addition of different auxins to the culture medium in concentrations up to 10 and 20 mg/1 did not increase root production by infected internodes.  tTokyo, Japan: International Society of Citricultural, 1981.