MULTINUCLEATE CONDITION OF PUCCINIA-STRIIFORMIS IN COLONIES ISOLATED FROM INFECTED WHEAT LEAVES WITH MACERATING ENZYMES

A fluorescence microscopy study was carried out to examine the multinu clear condition in parasitic colonies of one isolate of Puccinia strii formis in leaf tissue of a susceptible wheat. At 5 and 10 days after i noculation, colonies were isolated with macerating enzymes and sequent ially stained with 4'-6-diamidino-2-phenylindole and Calcofluor for nu clear counts in the intercellular hyphal cells, haustorium mother cell s, and urediniospores. In 10-day-old colonies, more than 98% of the hy phal cells located adjacent to the uredinia were binucleate. Elsewhere in the colonies, the hyphal cells were highly variable in nuclear num ber, approximately 20% contained two nuclei, 18% contained four, 26% c ontained six, and 28% contained eight. In 5-day-old colonies, the hyph al cells were also highly variable in nuclear number, regardless of wh ere they were located in the colony. The nuclear condition of haustori um mother cells was less variable; the majority contained either two o r four nuclei. All urediniospores examined were binucleate. In the par asitic state, the multinucleate condition apparently occurs only in P. striiformis and not in other cereal rust fungi.