Comparing the performance of a set of processing lines nearly isogenic for Pto, a gene conferring resistance to.
Pseudomonas syringae pv. tomato
Tanksley, S.1, Bernacchi, D.1, Fulton, T.1, Beck-Bunn, T.2, Emmatty, D.
3, Eshed, Y.4,
Inai, S.5, Lopez, J.6,
Petiard, V.7 ,
Sayama, H.5, Uhlig, J.2'& Zamir, D. 4
1 Department of Plant Breeding and Biometry, Cornell University, Ithaca, NY 14853
2 Seminis Vegetable Seeds, Woodland, CA 95695, U.S.A.
3 Heinz U.S.A., Stockton, CA 95201
4 Hebrew University,Rehovot 76-100, Israel
5 Nippon Del Monte,Numata, Gumma 378 Japan
6 Nestle R & D Center S.A_, Apartado 435, E-06080. Badajoz. Spain
7 Centre Recherche Nestle, 101 av. G. Eiffel, 37390 NOTRE DAME D'OE, Tours Cedex, France
Pto is a dominant gene on chromosome 5 providing protection against the bacterial pathogen
Pseudomonas syringae pv. tomato (Pitblado and MacNeill 1983). The disease caused by this pathogen, referred
to as bacterial speck, results in serious losses in many regions where processing tomatoes are grown. As a result,
Pto is being incorporated into most new processing variety releases.
Pto was introgressed into cultivated tomatoes from the closely related wild species, L. pimpinellifolium, and
is associated with as much as 20 cM of linked pimpinellifolium DNA (Martin et al. 1993). Whether this linked
foreign DNA has any effects on processing traits has not been determined. For this reason, we constructed a set
of Pto nearly isogenic lines(NILs) in the genetic background of the processing variety E6203. To construct these
NILs, the Pto gene, derived from an Israeli processing lines (H14-Pto), was backcrossed 6 times, using marker
assisted selection, into E6203 and selfed in the last generation to produce a homozygous resistant NIL (referred
to as Pto-R/R = TA537). In addition Pto-R/R was crossed back to E6203 to produce seed heterozygous for Pto in
the E6203 background (referred to as Pto-R/S).
Pto-R/R, Pto-R/S and E6203 (S/S) seedlings were transplanted into field plots of 20 plants each at
standard densities in the summer of 1996. The sites were in Akko, Israel (IS);
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