Evaluation of breeding utility of a chromosomal segment from Lycopersicon chmielewskii that enhances cultivated tomato soluble solids

A chromosomal segment from the wild tomato species, Lycopersicon chmielewskii, when backcrossed into the tomato cultivar VF145B-7879, increases fruit soluble solids concentration. In the investigation reported here, the near-isoline (VF145B-7M) homozygous for the chmielewskii (chm) chromosomal segment was crossed to the cultivar to study allelic interactions and then hybridized to three commercial cultivars (UC204c, E6203, and ChicoIII) to investigate the effect of this segment when heterozygous in different genetic backgrounds. Parents, isogenic hybrids, and unmodified hybrid controls were evaluated in three consecutive years of field study. The chm segment, when either homozygous or heterozygous, significantly increased soluble solids concentration by 13% and 12%, respectively, over VF145B-7879 (esc/esc), suggesting dominant gene action. Averaged across the three isohybrids and one isoline, one dose of this segment significantly increased soluble solids concentration by 6.0% compared to the unmodified hybrids and VF145B-7879. Other than increasing fruit total and soluble solids in mature-green and ripe-red tomatoes, no consistent negative effects of the chmielewskii segment were observed in the various genetic backgrounds on plant yield, fruit weight, or fruit pH. These results favor the use of this segment in breeding programs to develop fresh market and processing tomato cultivars with enhanced quality and reduced processed product dehydration costs.