Melon bacterial artificial chromosome (BAC) library construction using improved methods and identification of clones linked to the locus conferring resistance to melon Fusarium wilt (Fom-2)

Utilizing improved methods, two bacterial artificial chromosome (BAC) libra ries were constructed for the multidisease-resistant line of melon MR-1. Th e HindIII library consists of 177 microtiter plates in a 384-well format, w hile the EcoRI library consists of 222 microtiter plates. Approximately 95. 6% of the HindIII library clones contain nuclear DNA inserts with an averag e size of 118 kb, providing a coverage of 15.4 genome equivalents. Similarl y, 96% of the EcoRI library clones contain nuclear DNA inserts with an aver age size of 114 kb, providing a coverage of 18.7 genome equivalents. Both l ibraries were evaluated for contamination with high-copy vector, empty pInd igoBac536 vector, and organellar DNA sequences. High-density filters were s creened with two genetic markers FM and AM that co-segregate with Fom-2, a gene conferring resistance to races 0 and 1 of Fusarium wilt. Fourteen and 18 candidate BAC clones were identified for the FM and AM probes, respectiv ely, from the HindIII library, while 34 were identified for the AM probe fr om filters A, B, and C of the EcoRI library.