ISHS Acta Horticulturae 808: II International Symposium on Tomato Diseases
HIGH LEVEL OF RESISTANCE TO BACTERIAL WILT (RALSTONIA SOLANACEARUM) OBTAINED IN LARGE-FRUITED TOMATO BREEDING LINES DERIVED FROM HAWAII 7997 |
| Authors: | J.W. Scott, G.E. Vallad, J.B. Jones |
| Keywords: | bacterial spot, flavor, fruit size, Lycopersicon esculentum, Solanum lycopersicum, Xanthomonas |
| Abstract:
There have been difficulties in developing tomato (Solanum lycopersicum L.) lines with large-fruit (>200g) and high levels of resistance to bacterial wilt. It was previously reported that breeding lines Fla. 8109 (8109) had large fruit with resistance similar to that of Hawaii 7997 (H7997), the small-fruited, bacterial wilt resistant accession from which it was derived. Hypothetically a linkage was broken between a resistance gene and a gene that limited fruit size. Herein, 8109 had bacterial wilt resistance comparable to that of H7997 in all four seasons where they were compared. Fla. 8109 was crossed with 19 breeding lines and selections were made in subsequent generations for bacterial wilt resistance and improved horticultural traits with emphasis on large fruit. An array of large-fruited breeding lines from eight crosses at the F5 generation demonstrated resistance comparable to that of H7997. Fruit size and yield were measured on three of these along with their respective parents. For one family the F5 was significantly greater for yield and fruit size than both parents indicating transgressive segregation. Fruit size of the other two F5 lines was significantly greater than their respective recurrent parents, but differences were not significant compared to that of Fla. 8109. Yield differences were not significant in these two families. Subsequently, F7 lines were subjected to more severe bacterial wilt disease pressure. Selections for two of the eight crosses had resistance comparable to H7997 and greater than that of partially resistant ‘Neptune’. Selections of three other crosses were comparable to both H7997 and ‘Neptune’. All eight lines were more resistant than susceptible ‘Florida MH-1’. Thus, the resistance and large fruit size of Fla. 8109 has been recovered in some but not all lines while yields and other characteristics have been improved. Flavor in some of these lines was very good with improved sweetness compared to previous breeding material. Breeding implications of working with resistance derived from 8109 are discussed. | |
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