CALCIUM-OXALATE CRYSTAL-FORMATION IN RHIZOCTONIA-SOLANI AG-2-1 CULTURE AND INFECTED CRUCIFER TISSUE - RELATIONSHIP BETWEEN HOST CALCIUM ANDRESISTANCE

Crystals of various forms were observed in liquid cultures of Rhizocto nia solani AG2-1 and on the surface of infected hypocotyls of canola ( Brassica napus, cv. Westar), mustard (Sinapis alba, cv. Arda) and Came lina sativa. The crystals were identified as calcium oxalate based on solubility, staining reaction, potassium permanganate titration and en ergy-dispersive X-ray microanalysis. More calcium-containing crystals were formed on hypocotyls of the susceptible cv. Westar than on hypoco tyls of the resistant cv. Arda and on C. sativa, and on 1-wk-old plant s than on 3-wk-old plants. There was no significant difference in tota l calcium content in non-infected hypocotyl tissues among the three pl ant genera, and the calcium content did not increase with age of plant tissue. The production of oxalic acid in culture and the formation of calcium oxalate crystals in infected tissues suggested that calcium i n plant cells was sequestered by oxalic acid produced by R. solani.