RESEARCH REPORTS                                                             TGC REPORT 52, 2002 ______________________________________________________________________                             Wound infection was recorded on all accessions.  In all cases the pathogen was able to colonize the petiole stub, but significant quantitative differences were observed among  accessions  for  the  subsequent  development  of  stem  lesions  (Table  1).    Stem colonization was most severe on the fixed line Mospomorist of L. esculentum, used as a susceptible  control,  and  it  was  least  severe  among  accessions  of  L.  hirsutum  and  L. peruvianum.  For these less susceptible accessions, the size of the stem lesions rarely increased beyond the diameter of the petiole. Partial  resistance  was  also  observed  on  leaves.    Compared  to  L.  esculentum, symptoms  were  significantly  reduced  on  several  accessions  such  as  L.  chmielewskii 731089  and  L.  chilense  LA1969  (Table  1).    There  was  little  correlation  between susceptibility of stem and leaf tissue (r² < 0.04), and the accessions  with significantly smaller   stem   lesions   were   equally   or   more   susceptible   to   leaf   infection   than   L. esculentum.  However, the development of Botrytis lesions on the leaves appeared to be partially related to that of intumescences (Table 1). Stem  lesions  represent  the  most  frequent  and  the  most  damaging  of  Botrytis symptoms  in  heated  glasshouses  where  excess  humidity  is  usually  avoided.    In  this context, the high level of partial resistance to stem colonization found within the species L.  hirsutum  appears  promising  for  breeding  less  susceptible  tomatoes.    Further  work has been focused on the genetics, mechanisms and durability of partial resistance.    Literature cited : Chetelat, R.T., Stamova, L.  1999.  Tolerance to Botrytis cinerea. Acta Horticulturae 487:313-316. Egashira, H., Kuwashima, A., Ishiguro, H., Fukushima, K., Kaya, T., Imanishi, S.  2000. Screening of wild accessions resistant to gray mold (Botrytis cinerea Pers.) in Lycopersicon.  Acta Physiologiae plantarum 22:324-326. Moreau, P., Thoquet, P., Laterrot, H., Moretti, A., Olivier, J., Grimsley, N.H.  1997. A locus, ltm, controlling the development of intumescences, is present on chromosome 7. TGC Report 47:15-16. Nicot P.C., Baille A. 1996. Integrated control of Botrytis cinerea on greenhouse tomatoes. In: C.E. Morris, P.C. Nicot and C. Nguyen Thé (eds.). Aerial Plant Surface Microbiology. Plenum Publisher New York, ISBN 0-306-45382-7. pp 169- 189.   Nicot P.C., Pellier A.L., Moretti A., Caranta C., Rousselle P.  2000. Resistance of tomato to Botrytis cinerea. 12th. International Botrytis Symposium, Reims, 2000/07/03-08. University of Reims Champagne-Ardenne, Reims, France.   Abstract .P77.   Acknowledgements:    This  work  was  supported  in  part  by  private  breeders:  Gautier Graines,  Rijk-Zwaan  France  SARL,  Seminis  Vegetable  Seeds  France  S.A.,  Syngenta Seeds S.A.S., Takii Recherche France S.A., Tézier S.A., Vilmorin. 25

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