Variation among seven genotypes of Lycopersicon esculentum and 36 accessions of L. hirsutum for interspecific crossability

To improve the efficiency of introgressing genes from Lycopersicon hirsutum (H) into L. esculentum (E), environmental and genetic variation for the number of progeny per fruit from E × H crosses was quantified. Over three dates in a year, 36 H accessions were crossed to seven E accessions in a greenhouse. The proportion of total variation for the number of E × H progeny per fruit due to environment (dates, location, and error), H accession, E accession, interactions between E and H, and interactions between accessions and environments was 0.42, 0.26, 0.12, 0.11, and 0.09, respectively. Sampling greater numbers of fruit on a single date improved the efficiency of recovering progeny more than increased sampling over time. The specific combination of E and H parents can profoundly affect the number of E × H progeny recovered and therefore the efficiency of gene introgression. Accessions of H from the southern edge of the species' natural geographic range generally yielded few to zero progeny per fruit in crosses with E. In contrast to the southern H accessions, most northern accessions produced greater than 40 E × H progeny per fruit. Most genes within H should be readily accessible for tomato breeding but genes that are found only in southern H accessions may be challenging to introgress. This revised version was published online in July 2006 with corrections to the Cover Date.