02414nas a2200229 4500008004100000022001400041245009500055210006900150260002900219300001400248490000800262520170700270653002701977653001502004653001802019653001302037653001402050100002302064700002102087700002102108856005502129 2012 eng d a1439-043400aDefining plant resistance to Phytophthora cinnamomi: a standardized approach to assessment0 aDefining plant resistance to Phytophthora cinnamomi a standardiz bBlackwell Publishing Ltd a269–2760 v1603 a

Phytophthora cinnamomi is a soil-borne plant pathogen that causes devastating disease in agricultural and natural systems worldwide. While a small number of species survive infection by the pathogen without producing disease symptoms, the nature of resistance, especially under controlled conditions, remains poorly understood. At present, there are no standardized criteria by which resistance or susceptibility to P. cinnamomi can be assessed, and we have used five parameters consisting of plant fresh weight, root growth, lesion length, relative chlorophyll content of leaves and pathogen colonization of roots to analyse responses to the pathogen. The parameters were tested using two plant species, Zea mays and Lupinus angustifolius, through a time course study of the interactions and resistance and susceptibility defined 7 days after inoculation. A scoring system was devised to enable differentiation of these responses. In the resistant interaction with Z. mays, there was no significant difference in fresh weight, root length and relative chlorophyll content in inoculated compared with control plants. Both lesion size and pathogen colonization of root tissues were limited to the site of inoculation. Following inoculation L. angustifolius showed a significant reduction in plant fresh weight and relative leaf chlorophyll content, cessation of root growth and increased lesion lengths and pathogen colonization. We propose that this technique provides a standardized method for plant–P. cinnamomi interactions that could be widely used to differentiate resistant from susceptible species.

10aPhytophthora cinnamomi10aresistance10aroot pathogen10aZea mays10azoospores1 aAllardyce, Jane, A1 aRookes, James, E1 aCahill, David, M uhttp://dx.doi.org/10.1111/j.1439-0434.2012.01895.x