ADVANCED BACKCROSS QTL ANALYSIS OF TOMATO - II - EVALUATION OF NEAR-ISOGENIC LINES CARRYING SINGLE-DONOR INTROGRESSIONS FOR DESIRABLE WILD QTL-ALLELES DERIVED FROM LYCOPERSICON-HIRSUTUM AND L-PIMPINELLIFOLIUM

Improved-processing tomato lines were produced by the molecular breedi ng strategy of advanced backcross QTL (AB-QTL) analysis. These near-is ogenic lines (NILs) contained unique introgressions of wild alleles or iginating from two donor wild species, Lycopersicon hirsutum (LA1777) and L. pimpinel-lifolium (LA1589). Wild alleles targeted for trait imp rovement were selected on the basis of previously published replicated QTL data obtained from advanced backcross populations for a battery o f important agronomic traits. Twenty three NILs were developed for 15 genomic regions which were predicted to contain 25 quantitative trait factors for the improvement of seven agronomic traits: total yield, re d yield, soluble solids, brix x red yield, viscosity, fruit color, and fruit firmness. An evaluation of the agronomic performance of the NIL s in five locations worldwide revealed that 22 out of the 25 (88%) qua ntitative factors showed the phenotypic improvement predicted by QTL a nalysis of the BC3 populations, as NILs in at least one location. Per- location gains over the elite control ranged from 9% to 59% for brix x red yield; 14% to 33% for fruit color; 17% to 34% for fruit firmness; 6% to 22% for soluble-solids content; 7% to 22% for viscosity; 15% to 48% for red yield, and 20% to 28% for total yield. The inheritance of QTLs, the implementation of the AB-QTL methodology for characterizing unadapted germplasm and the applicability of this method to other cro ps are discussed.