Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2005
Publication Date: May 1, 2005
Citation: Brown, C.R., Mojtahedi, H. 2005. Evidence of systemic acquired resistance to Meloidogyne chitwoodi, race 2, conferred by gene for resistance to race 1 from Solanum bulbocastanum. American Journal of Potato Research. 82:59. Technical Abstract: Columbia root-knot nematode, Meloidogyne chitwoodi (MC), is an important pest of potato in the warmer production areas in the Pacific Northwest of USA. This nematode pest consists of host races and the pathotypes in the region. Present control measures require costly chemical fumigation wherever MC is present. Resistance to MC, race 1 (MC1), was discovered in the Mexican wild species Solanum bulbocastanum (SB), which is controlled by a single dominant locus R Mc1(blb), and was incorporated into advanced breeding lines by backcrossing. Although SB displayed resistance to races MC1 and MC, race 2 (MC2), progeny of an intra-bulbocastanum cross (resistant x susceptible) segregated for single and double resistance to the races. It was found that in progeny harboring R Mc1(blb), when challenged by MC1, there was an elicitation of a resistance response to subsequent inoculation by MC2. Yet, inoculation by MC2 alone produced no resistance response at all. The signaling of a general resistance fits the definition of systemic acquired resistance (SAR). The SAR elicited by exposure to MC1 acted to limit reproduction of MC2 on the roots to a non-host reaction (reproductive factor = (final no. of eggs / initial no. eggs) < 0.1). In advanced breeding materials, derived by four backcrosses of R Mc1(blb) into horticulturally improved introgressants, prior exposure to MC1 additionally conditioned tubers to resist development of second stage juveniles of MC2 at tuber penetration, the point at which economic damage normally begins to occur. Thus the SAR appeared to function during reproduction on the roots and at tuber penetration.