INDUCED RESISTANCE TO ERWINIA-CAROTOVORA SSP ATROSEPTICA, THROUGH THETREATMENT OF SURFACE WOUNDS OF POTATO-TUBERS WITH ELICITORS

We have investigated the ability of mixed oligogalacturonides, a cell wall hydrolysate from Phytophthora sojae Hildebrand, and chitosan olig omers to induce resistance to Erwinia carotovora ssp. atroseptica in p otato tubers (cv. Pentland Squire). Natural infection by Erwinia in st ored potatoes generally originates in the surface tissues which have a markedly different biochemical composition to the perimedullary tissu e. We therefore investigated the effect of different elicitors in indu cing resistance in 2mm deep wounds made on the surface of potato tuber s. When wounded in this way and stored at 20 degrees C and 100% relati ve humidity, tubers developed a significant level of natural resistanc e within 24 h. When the potatoes were treated with oligogalacturonides , or Phytophthora cell wall hydrolysate at the time of wounding and ch allenged with inoculum 8 h later, a significant reduction in disease o ccurred. Treatment with the chitosan elicitor had no effect on resista nce.