A tomato plant with patches of green and white offered researchers a way to investigate leaf variegation. In an April 2024 study in BMC Plant Biology, genetic mapping pointed to an FtsH-related gene as a candidate behind the pattern. The work connected leaf colour, cell structure and inheritance, while leaving the proposed molecular mechanism open to testing.
Following leaf variegation through generations
The plant came from a tomato population produced using ethyl methanesulfonate, or EMS, a chemical that introduces random mutations. Its leaves contained dark green, medium green, light green and white sectors.
Breeding experiments supported recessive inheritance. That pattern is consistent with plants needing two copies of a relevant altered allele to display the trait. It helped the team narrow the genetic explanation, but did not by itself identify the responsible gene.
Looking beneath the colours
Microscopy and pigment measurements showed that the differently coloured areas also differed internally. White sectors contained very little photosynthetic pigment and showed severely abnormal plastids, the cellular structures from which chloroplasts develop. The researchers also used image analysis to measure the areas occupied by the different colours.
These approaches answer different questions. A photograph records where the colours appear. Pigment measurements and microscopy examine what accompanies those colours inside the leaf. Genetic mapping then asks which inherited DNA differences track the visible trait.
Why an FtsH gene became a candidate
Comparing DNA from green and variegated offspring highlighted a region on chromosome 4. The researchers prioritised an FtsH-like gene, LOC100037730, related to the Arabidopsis gene VAR1. FtsH proteins include enzymes involved in maintaining the photosynthetic machinery in chloroplasts, making this a biologically plausible lead.
The associated DNA change was synonymous: it did not change the encoded amino acid. Instead, computational analysis suggested that it might alter a possible microRNA interaction with the gene’s messenger RNA. MicroRNAs are small RNA molecules that can regulate gene expression.
The distinction matters. A synonymous variant does not automatically change an enzyme’s amino-acid sequence or catalytic properties. A regulatory explanation needs evidence that the RNA interaction occurs and affects the relevant gene or protein. The paper presents this route as a hypothesis for further investigation.
Where the evidence leads next
An inherited association provides a target for experiments. Recreating the candidate change in an otherwise green plant, or restoring a functional gene copy in the mutant, would help test whether that change causes the phenotype. Measurements of the proposed RNA interaction and its effects would address the mechanism more directly.
For horticulture, the immediate value is a clearer research question. A finding in one tomato line does not yet provide a reliable method for producing a chosen pattern in other plants, or establish improved crop performance. It gives researchers a candidate to investigate and a set of visible and cellular features against which to assess the result.
Related research: Scientists discover an enzyme that forms fractal patterns.
Original research
Dechkrong, P., Srima, S., Sukkhaeng, S., Utkhao, W., Thanomchat, P., de Jong, H. and Tongyoo, P. (2024). Mutation mapping of a variegated EMS tomato reveals an FtsH-like protein precursor potentially causing patches of four phenotype classes in the leaves with distinctive internal morphology. BMC Plant Biology, 24, 265.
Update note, 23 September 2026: This archived report has been revised to clarify the candidate-gene evidence, the proposed RNA mechanism and the image attribution.
