Development of RAPD-AFLP map of eggplant and improvement of tolerance to Verticillium wilt

Verticillium wilt is one of the most serious diseases in eggplant and one of the main goals of eggplant breeding is the achievement of Verticillium wilt tolerant hybrids. Solanum sodomeum L. has shown a mechanism of partial resistance against Verticillium wilt. Interspecific hybrids were obtained by using an accession of S. sodomeum from Sicily and the eggplant variety Buia. The results of the screenings for eggplant genotypes tolerant/resistant to Verticillium wilt by using backcrosses are reported. In a naturally infected field, from 1998 to 2001, the resistance to V dahliae of backcrossed progenies was increased by about 60%. The interspecific hybrids were both selfed and backcrossed using different types of eggplant. An integrated linkage map of eggplant (Solanum melongena L.) has been obtained by using 48 plants of an F-2 population. Starting from a genetic RAPDs map with similar to 100 markers mapped on 13 linkage groups, 4 AFLPs primer combinations were screened in order to improve the genetic map with the aim to achieve markers linked to Verticillium tolerance. Mendelian segregation of loci was verified by chi-square tests of the expected 3:1 and 1:1 ratios. Marker order was determined and all the data were combined to construct the most likely map. The integrated analysis of markers resulted in the construction of a map consisting of 273 loci and 12/13 linkage groups spanning 736 cM in a total. Linkage between different AFLP markers and the tolerance to Verticillium is discussed.