Tolerance to salt stress and blossom-end rot in an introgression line, IL8-3, of tomato

Introgression lines consisting of genomic segments of wild tomato species replaced by homologous regions in the background of cultivated tomato species are useful for evaluating individual QTL and lack most of the negative traits of the wild species. Since little information is available on environmental stress in introgression lines, IL8-3, in which a Solanum pennellii chromosomal segment is introgressed into S. lycopersicum chromosome 8, was evaluated to explore useful traits related to environmental stress tolerance. Higher germination rate of IL8-3 compared with the S. lycopersicum parent M82d under salt stress suggests the presence of a salt tolerance gene in the IL8-3 region of the S. pennellii genome. Osmotic regulation and abscisic acid (ABA) response were found to be involved in the mechanism of salt tolerance. The incidence of blossom-end rot in IL8-3 was lower than that in M82d, and the tolerance to blossom-end rot was found to be present as a dominant trait in the IL8-3 region. The tolerance to blossom-end rot in IL8-3 is likely due to its ability to uptake and distribute calcium ions (Ca2+) and potassium ions (K+) because the Ca and K content of IL8-3 fruit was found to be higher than that of M82d fruit. Both loci affecting the tolerance to salt stress and blossom-end rot were mapped to the same narrow region, IL8-3-83, within IL8-3.

► An introgression line, IL8-3, carries an introgression from Solanum pennellii.
► Germination rate was higher in IL8-3 under salt stress.
► The incidence of blossom-end rot was lower in IL8-3.
► The tolerance mechanisms were suggested.
► Both loci affecting the tolerance were mapped to the same narrow region within IL8-3.