Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: W66 - ADVANCED BACKCROSS QTL ANALYSIS IN TOMATO: IDENTIFICATION OF DESIRABLE WILD QTL-ALLELES AND PRODUCTION OF IMPROVED CULTIVATED LINES.
W66
ADVANCED BACKCROSS QTL ANALYSIS IN TOMATO: IDENTIFICATION OF DESIRABLE WILD QTL-ALLELES AND PRODUCTION OF IMPROVED CULTIVATED LINES.
BERNACCHI, DARIO, Theresa Beck-Bunn, Davy Emmatty, Yuval Eshed, Shuji Inai, Joaquin Lopez, John Uhlig, Vincent Petiard, Dani Zamir, Steven D. Tanksley
647. Dept Plant Breeding, 252 Emerson Hall, Cornell University, Ithaca, NY 14853
A new molecular breeding strategy, Advanced Backcross QTL analysis (AB QTL) has been tested in tomato. This methodology uses QTL-selected alleles from wild species to improve the agronomic performance of elite lines. The AB QTL strategy has been applied in tomato using L. hirsutum LA1777 and L. pimpinellifolium LA1589 as the wild species donor and the elite processing variety E6203 as the recurrent parent. Marker assisted selection was used to eliminate undesirable wild alleles from the BC1 and BC2 populations. The BC2 populations were genotyped with molecular markers throughout the genome and the agronomic performance of derived BC3 lines was evaluated in 3 locations. QTL were identified for all traits studied; and, for approximately 20% of the QTL, the wild alleles were associated with improvement in the trait. Based on the QTL results, 15 genomic regions were targeted for production of lines containing single wild introgressions in an L. esculentum genetic background. These near isogenic lines (NILs) were obtained by marker assisted selection from segregating BC3S1 seedlings. A total of 24 NILs corresponding to 25 wild QTL were produced and evaluated in 5 locations worldwide. Of the 25 QTL transferred into the cultivated genetic background, 22 (88%) showed phenotypic improvement as predicted from QTL analysis in at least 1 of the locations. Per location gains over the elite controls ranged from 9% to 59% for brix x red yield; from 14% to 33% for fruit color; from 17% to 34% for fruit firmness; from 6% to 22% for soluble solids content; from 7% to 22% for viscosity; from 15% to 48% for red yield and from 20% to 28% for total yield. These results indicate that AB QTL analysis effectively integrates QTL mapping and variety development and that it can be used to accelerate genetic gains and selectively broaden the genetic base of crop plants. Furthermore, it illustrates the agronomic potential of wild germplasm.