Phytophthora cinnamomi is the most devastating forest disease world wide. It is mostly an introduced pathogen as in southern Australia where it devastates native forests, woodlands and heaths, directly and indirectly affecting vegetation types from a wide range of families. P. cinnamomi has also been introduced into European and North American hardwood and softwood forests. The pathogen is now cosmopolitan in the horticultural industry and it is a particular problem in nurseries. The significance of this is that P. cinnamomi has the opportunity to interact with and the potential to evolve in association with a wide range of new hosts and in a wide range of ecosystems. Distribution of the pathogen at the local, national and international level is of concern to the management of forest, native vegetation and horticulture industries

Colquhoun, I.J.

Hardy, G.E.St.J.

Hüberli, D.

Tommerup, I.C.

English

Research Repository

   MURDOCH RESEARCH REPOSITORY        Tommerup, I.C., Hardy, G.E.St.J., Hüberli, D. and Colquhoun, I.J. (1997) Selecting plants resistant to Phytophthora cinnamomi. In: 11th Biennial Conference of the Australasian Plant Pathology Society, 29 September - 2 October, Perth, Western Australia,  pp 89.     http://researchrepository.murdoch.edu.au/12468/         It is posted here for your personal use. No further distribution is permitted.   b .. SELECTING PLANTS RESISTANT TO PHYTOPHTHORA CINNAMOMI I. e. Tommerupl, G.E. St. J.  Hardi, D. HUberli2 and L J. Colquhoun' Forestry and Forest Productsl, CSIRO Perth, Private Bag PO Wembley, 6014, Murdoch Universiti, Murdoch, 6153 and Alcoa of Australia Limited', PO Box Booragoon 6150  Western Australia INTRODUCTION Phytophthora  cinnamomi  is  the  most devastating forest disease world wide.  It is mostly an introduced pathogen as in southern  Australia  where  it  devastates  native  forests, woodlands  and  heaths,  directly  and  indirectly  affecting vegetation types from a wide range of families. P.  cinnamomi has also been introduced into European and North American hardwood  and  softwood  forests.  The  pathogen  is  now cosmopolitan  in  the  horticultural  industry  and  it  is  a particular  problem in  nurseries.  The significance of this  is that  P.  cinnamomi has the  opportunity to  interact with  and the  potential to evolve in  association  with  a  wide  range of new hosts and in a wide range of ecosystems. Distribution of the  pathogen at the local, national and international level is of concern to the management of forest, native vegetation and horticulture industries. Selecting,  breeding  and  deploying  resistant  plants,  Iding  Australian  native  species,  is  one  avenue  for olling  the  effects  of  the  pathogen  and  rehabilitating n  l  ral ecosystems prone to the disease.  P.  cinnamomi. is an introduced in southern Australia but it may be indigenous in some  regions  of  the  north  east.  In  the  south,  disease resistance in native vegetation involves non-coevolved host-pathogen associations and resistance is  most probably due to general  and  not  host-specific  genetic  resistance  factors.  In southern  Australian  plant  communities  there  are  wide differences in field resistance among species of some genera and  increasing evidence for variable resistance within some species. P.  cinnamomi is  a  highly  variable pathogen worldwide. In  Australia,  isolates  vary  considerably  in  pathogenicity, physiological and morphological phenotypes (I, 2,).  Genetic variation  within  isoenzyme  groups  has  now  been  shown unequivocally  (3,  4).  Recent  evidence  has  increased  for major  interactions  among three components:  pathogenicity, host  resistance  and  environmental  factors.  Host-P. cinnamomi  interactions occur at several levels. Resistance,  expressed  at  the  sub-species  level  is  being •uated  in  breeding  programmes  for  valuable  forest  and ultural species. nvironmental factors interact with host resistance and P. cinnamomi capacity to cause disease (Figure I). Disease control in long-lived woody plants is a long term vmture.  Programmes  selecting  and  breeding  for  disease resistance  in  Australian  native  forest,  woodland,  heath  and woody  horticultural  species  are  challenged  by  the  need  to develop 'long-term' resistance. METHODS We have developed a factorial approach to disease resistance screening for woody vegetation incorporating a set of isolates differing in pathogenicity host age factors, host tissue water content and temperature, with each factor being selected because it induces distinct host-resistance responses. Screening also includes pathogen detection as lack of lesion development may merely be masking pathogen colonisation. Subsequent lesion development may proceed if environmental conditions change. RESULTS AND DISCUSSION A  significant  feature  of disease  expression  due  to  P. cinnamomi is the change in association with a range of site, soil and seasonal environmental factors  (5,  6).  Variation in temperature and moisture, independently and synergistically, affect all  aspects of the  pathogen life cycle and  they  host-pathogen  disease  cycle.  Importantly  for  disease interpretation, lesion development is changed by temperature and moisture. Our recent research results  are consistent with  the view that  screening for  disease  resistance to  P.  cinnamomi  may have increased long-term outcomes if it takes account of host, pathogen  and  environmental  factors  which  change  disease expression. ACKNOWLEDGMENTS LWRRDC funded part of this work. REFERENCES 1.  Dudzinski,  MJ.  Old,  K.M.  and  Gibbs,  RJ.  (I 993}. Pathogenic  variability  in  Australian  isolates  of Phytophthora cinnamomi. Australian Journal of Botany 41,721-732. 2.  HUberli,  D.,  Hardy,  G.E.  St.  J.  and  Tommerup,  I.e. (1997)  Morphological  and  physiological  characteristics of two Phytophthora cinnamomi populations. TheseAbs. 3.  Tommerup,  I.e.  (1995)  Genetic  variation  in  isozyme groups of Phytophthora cinnamomi APPS abstracts. 4.  Dobrowolski,  M.,  Tommerup,  I.e.  and  O'Brien,  P.A. (1997).  Microsatellite  DN  markes  for  pathogen population nalysis.  These Abstracts 5.  HUberli,  D.,  Tommerup,  I.C.,  Hardy,  G.E.  St.  J.  and Colquhoun, 1.1.  (1997)  Tempeature changes resistance of  jarrah to Phytophthora cinnamomi. These Abstracts. 6.  Shearer, B.L. and Tippett, J.T.  (1989 Jarrah dieback: the dynamics  and  management  Phytophthora  cinnamomi  in the jarrah (Eucalyptus marginata) forest of south-western Australia. CALM Research Bulletin No.3 P.  cinnamomi pathogenicity:  species-isolate levels Host resistance:  species, sub-species, individual plant levels· Environmental factors Figure 1.  Plant-P. cinnamomi interactions occur at the levels of host plant species, sub-species or individual plants and respectively, P.  cinnamomi species or individual isolates.  Interaction levels involving P.  cinnamomi sub-species groups have yet to be identified. 89 

(I 993}. Pathogenic variability in Australian isolates of Phytophthora cinnamomi.

Genetic variation in isozyme groups of Phytophthora cinnamomi APPS abstracts.

Jarrah dieback: the dynamics and management Phytophthora cinnamomi in the jarrah (Eucalyptus marginata) forest of south-western Australia.

Microsatellite DN markes for pathogen population nalysis. These Abstracts

Morphological and physiological characteristics of two Phytophthora cinnamomi populations.

Tempeature changes resistance of jarrah to Phytophthora cinnamomi. These Abstracts.

Selecting plants resistant to Phytophthora cinnamomi

http://researchrepository.murdoch.edu.au/12468/

Selecting plants resistant to Phytophthora cinnamomi

Abstract

Similar works

Full text

Available Versions

Research Repository