RESEARCH REPORTS                                                          TGC REPORT 52, 2002 __________________________________________________________________________________________ ones that are detected in West Europe and North America (Fry W., Goodwin S., Matuszak J. et al, 1991; Drenth A., Turkensteen L., Govers F., 1993; Day J.P., Shattock  R.C.,  1997).  This  changed  situation  requires  reevaluation  of  tomato patterns  for  resistance  to  the  new  populations  of  the  late  blight  pathogen.  Our study  was  aimed  at  evaluating  tomato  breeding  material  in  naturally  occurring epidemics in the Moscow Region.   Materials and methods   During three epidemic years (1998–2000) we screened for resistance to the late blight   tomato   collection   including   more   then   1500   tomato   accessions   of interspecies  hybrids  and  selected  lines.  This  plant  material  was  obtained  from VNIO (All-Russian Institute for Vegetable Crops, Mitichi, Moscow Region, Russia) and  VIR  (Vavilov  Plant  Research  Institute,  St.  Petersburg,  Russia).  Evaluation was carried out in greenhouses of VNIO in Bukovo, the Moscow Region. The  susceptible  control  genotype  was  a  commercial  hybrid  widely  grown  in Russia,  provided  by  VNIO.  The  resistant  control  was  West  Virginia  63.  The accessions were supplied by VIR. Tomato stem, fruit, and foliage infections were taken    into    account.    Scale    (0-4    marks)    for    each    organ    was    involved. Simultaneously   Phytophthora   isolates   were   collected   from   different   tomato organs,  and  isolated  in  pure  culture  on  oatmeal  agar.  Obtained  isolates  were assessed  for  the  mating  types,  resistance  to  fungicides:  dimethomorph  and metalaxyl,  pathogenic  features,  and  molecular  markers.  To  assess  the  mating type  the  strains  were  crossed  on  oatmeal  medium  with  both  the  A1  and  A2 testers, obtained from the Dep. Mycology and Algology, Moscow State University. The  mating  type  was  determined  by  inspecting  for  presence  or  absence  of oospores in a border zone between grown colonies. Resistance to fungicides was determined  by  growing  of  the  isolates  on  oatmeal  medium  supplemented  with dimethomorph in concentration 3mg/ml, or with metalaxyl in concentration 10 or 100  mg/ml.  Tomato  races  of  the  pathogen  were  defined  using  a  bioassay  to inspect for disease symptom control patterns on Talallixin (Ph-0), Ottawa-30 (Ph- 1), and West Virginia 63 (Ph-2). PCR-tests to define mitochondrial and nuclear DNA-polymorphism were performed as described elsewhere (Drenth et al, 1993; Maleeva et al, 1999). Results The  pathogen  attacked  all  above  ground  parts  of  tomato  plants:    stems,  fruits, foliage   branches   and   even   flowers.   Data   on   average   severity   accounted separately for each organ were obtained. Eighteen selective lines (Backcrosses, F3-F8  generations)  showed  the  highest  resistance  for  all  organs  (0-2  marks). Susceptible  control  plants  were  severely  diseased  (4  marks).  The  results  are presented  in  Table  1.  These  lines  were  created  involving  different  tomato  wild species, such as: L. esculentum var. cerasiforme, L. pimpinellifolium, L. hirsutum, L. hirsutum var. glabratum, L. peruvianum, L. humboldtii, and L. cheesmanii. 15

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