Citrate and Malate Concentrations in Tomato Fruits: Genetic Control and Maturational Effects1

Abstract

There is continual change in the acidity of tomato fruits during development and maturation. The concn increases during development and reaches a maximum near incipient color, then decreases until well beyond maturity. The inheritance of citrate and malate concn in ‘Tondo Liscio’ (TL) and PI 263713 (PI) is controlled by a single gene for each compound. The dominant alleles, which were linked in the coupling phase in PI, condition a high concn of citrate and a low concn of malate. Recombination was about 18%. Study of divergent tomato accessions indicated that there are factors which condition higher and lower concn of citrate than the range delimited by TL and PI. There appears to be more than one malate factor controlling higher concn, but many tomato accessions are similar to the dominant low parent (PI). Current evidence indicates that there is no practical reason to breed for a specific citrate/malate ratio.