Incomplete dominance of bacterial wilt resistance.

The tomato line LE 79 (CL 32d-0-1-1-1-1-19 GS) was found to be resistant to bacterial wilt caused by race 1 of Pseudomonas solanacearum E.F. Smith under in vivo and in vitro (89.5 and 100% survival respectively) conditions. To study the mode of inheritance of resistance, this line was crossed with Pusa Ruby (a susceptible variety). The F1s, F2s, BC1s and BC2s were grown in a wilt infested soil. The temperature was kept below 32 deg.C. The data (Table 1) showed a monogenic and incompletely dominant gene action. The gene responsible for resistance manifested a penetrance of 72%.

Table 1.   Inheritance of resistance to bacterial wilt
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                                        Expected
                                        ratio
          Number   of   plants          assuming
Gener-    ___________________________   partial     
ations  Total  Resistant  Susceptible   penetrance X^2*^   P
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Pl(LE 79)  50     36         14          __                __

P2 
(Pusa Ruby)50      0         50          __                __

Fl         50      6         44          __                __

F2        200     41(48)    159(152)  0.94:3.04   1.32  0.3-0.2

BC1

(F1xLE79) 200     71(84)    129(116)  0.84:1.16   3.47  0.1-0.05

BC2
(F1xPusa Ruby) 
          200     18(12)    182(188)  0.06:0.94   3.19  0.1-0.05
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*X^2^  = 3.84;  (P = 0.05)