GENES FROM LYCOPERSICUM CHMIELEWSKII THAT AFFECT TOMATO SOLUBLE SOLIDS, pH, AND YIELD.

Abstract

Two chromosomal segments from the wild tomato L. chmielewskii have been introgressed into the L. esculentum genome. Using molecular markers they have been mapped to the middle and terminal regions of chromosome 7 (7M and 7T, respectively). This study was conducted to further clarify the physiological influence of the introgressed segments on tomato soluble solids, and other fruit and yield parameters. Sixty-four BC2F5 recombinant inbreds were developed from a cross using LA1501 (L. esculentum line that contains both fragments from L. chmielewskii) as the donor parent, and VF145B (processing cultivar) as the recurrent parent. Recombinant inbreds were classified in four groups (++: inbreds without either of the fragments, 7M+: with only the 7M fragment, +7T: with only the 7T fragment and, 7M7T: with both fragments) based on RFLP information, and then compared to each other for all the parameters under study. Inbreds homozygous for the 7M fragment displayed greater soluble solids (26%) and higher pH (0.10) than the control group (++), through a physiological mechanism related to water uptake. The 7L fragment did not influence either soluble solids or pH, but was observed to significantly increase fruit yield by 11%. A gene or genes that increase yield without affecting soluble solids or pH may have potential in the development of commercial cultivars.