01892naa a2200205 a 450000100080000000500110000800800410001902200140006010000230007424501280009726000090022552012760023465300130151065300210152365300130154465300250155770000150158270000190159777300700161616340862023-05-17       1995    bl uuuu     u00u1 u    #d  a0167-68571 aNAVAS-CASTILLO, J.  aCitrus psorosis, ringspot, cristacortis and concave gum pathogens are manintained in callus culture.h[electronic resource]  c1995  aCallus cultures were established from citrus explants infected with several virus-like pathogens of the psorosis group (psorosis A, psorosisB, ringspot, cristacortis, or concave gum), and successively subcultured for up to 16 months. Pineapple sweet orange or Duncan grapefruit seedlings graft-inoculated with callus pieces, and incubated in a temperature-controlled greenhouse, developed symptoms characteristic of these diseases, whereas similar indicator plant inoculated with callus developed from healthy explants remained symptomless. Calli infected with cristacortis or concave gum pathogens induced in young leaves of indicator plants chlorotic flecking and, occasionally, an oak leaf pattern. Those infected with psorosic (A or B) or ringspot induced a shock reaction in the first flush, and chlorotic flecks in young leaves developed in successive flushes. Calli from psorosis B-infected plants caused in addition blisters in mature shoots and chlorotic blotches with gummy pustules in the underside. These results indicate that the agents causing diseases of psorosis group can be maintained in callus culture. Nevertheless, trials to purify and detect specific 48 k-protein associated with psorosis and ringspot isolates from infected calli were unsuccessful.  aIndexing  aIndicator plants  aSymptoms  aVirus-like pathogens1 aMORENO, P.1 aDURAN-VILA, N.  tPlant Cell, Tissue and Organ Culturegv.40, n.2, p.133-137, 1995.