Altered distribution of susceptibility phenotypes implies environmental modulation of genetic resistance

Abstract

Resistance to disease is determined by the genetic capacity of a plant to recognize and respond to a pathogen, as modified to varying degrees by the environment in which the interaction occurs. Physical factors such as temperature and moisture can limit the ability of a pathogen to infect and cause disease, and may also influence the response of the host through effects on gene expression and/or by imposing constraints on physiological activities required to deliver an effective defense. Recent research has also drawn attention to the potential for the biotic environment to modulate susceptibility to disease. Thus, resistance may be enhanced by endophytic microbes and also by sub-lethal exposure to a plant pathogen. For example, studies under controlled conditions document that systemic-induced resistance (SIR) to pitch canker, caused by Fusarium circinatum, is operative in Pinus radiata D. Don (Monterey pine) (Bonello et al. 2001). Evidence for SIR in natural populations of P. radiata derives from studies showing that trees are more resistant to pitch canker in areas where the disease is of long residence than trees in areas where the disease is only recently established. Likewise, in a given stand, trees tend to become more resistant with time after establishment of pitch canker (Gordon et al. 2011). These observations suggest that susceptibility to a disease may be influenced as much by the history of exposure to a pathogen as by inherent genetic resistance.

Parent Publication

• Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees

Citation

Gordon, Thomas R.; McRoberts, Neil. 2012. Altered distribution of susceptibility phenotypes implies environmental modulation of genetic resistance. In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 2012. Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees. Gen. Tech. Rep. PSW-GTR-240. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. pp. 156-158.