Dani Zamir's group (Hebrew Univ. of Jerusalem, Israel) developed a ‘second generation’ set of S. pennellii introgression lines (accessions LA4028-LA4103) in the background of S. lycopersicum cv. M-82 (LA3475). Similar to the original population, each stock is homozygous for a single chromosome segment introgressed from S. pennellii LA0716, such that the entire wild parent genome is represented in a group of 50 lines. The new library also includes 25 sub-ILs with shorter segments that improve mapping resolution. The purity and isogenicity of each line has been improved and verified by marker-assisted selection.
All lines are homozygous and true breeding, except IL8-1 (LA4071) which contains two overlapping segments that segregate due to the action of a gamete eliminator gene that blocks pollen transmission of the longer introgressed segment. Plants heterozygous for the long and short introgressions are selected in each generation.
The majority of lines are reasonably fertile and can be multiplied using field plantings. However, some ILs (listed below) are partially sterile, especially under field conditions, but yield satisfactorily if grown in the greenhouse and manually self-pollinated.
Partially sterile ILs
IL 1-1 LA4028
IL 1-2 LA4031
IL 1-3 LA4032
IL 2-1 LA4035
IL 2-3 LA4038
IL 2-4 LA4039
IL 3-2 LA4044
IL 3-3 LA4045
IL 3-4 LA4046
IL 3-5 LA4047
IL 4-1 LA4048
IL 4-4 LA4053
IL 5-3 LA4056
IL 5-4 LA4057
IL 6-2 LA4060
IL 6-2-2 LA4061
IL 7-2 LA4065
IL 7-3 LA4066
IL 8-3 LA4076
IL 11-1 LA4092
IL 11-3 LA4094
IL 12-3 LA4100
Several lines contain monogenic morphological traits (below) that can be used to verify line identity and purity:
| Gene symbol | Gene name | IL | Accession(s) |
| r | yellow fruit flesh | IL 3-2 | LA4044 |
| Cwp1 | Cuticular water permeability1 | IL 4-4 | LA4053 |
| obv^+ | obscuravenosa (clear vein allele) | IL 5-4 | LA4057 |
| ndw | necrotic dwarf | IL 6-2, 6-2-2 | LA4060, 4061 |
| sp^+ | self-pruning (indeterminate habit allele) | IL 6-2, 6-3 | LA4060, 4062 |
| B | Beta-carotene | IL 6-3 | LA4062 |
| u^+ | uniform ripening (green shoulders allele) | IL 10-1, 10-1-1 | LA4087, 4088 |
| h | hairs absent | IL 10-2 | LA4089, 4090 |
| Del | Delta-carotene | IL 12-2, 12-3 | LA4099, 4100 |
For a complete listing of the accessions making up the S. pennellii IL set, search Database Queries/Core Collections and Mapping Populations.
More detailed information on the breakpoints of each introgressed segment can be found on the Solanceae Genomics Network website and in the following publications:
Alseekh, S., Ofner, I., Pleban, T., Tripodi, P., Di Dato, F., Cammareri, M., . . . Zamir, D. (2013) Resolution by recombination: breaking up Solanum pennellii introgressions. Trends in Plant Science, 18, 536-538.
Chitwood, D. H., Kumar, R., Headland, L. R., Ranjan, A., Covington, M. F., Ichihashi, Y., . . . Sinha, N. R. (2013) A quantitative genetic basis for leaf morphology in a set of precisely defined tomato introgression lines. Plant Cell, 25, 2465-2481.