A group of researchers with Spanish participation, have found a mutated gene that causes tomatoes to have less sugar and therefore taste worse.
Specifically, researchers have described in Science magazine the molecular basis by which a uniform ripening in tomatoes (red very attractive but less flavor) occurs and have found that a variation in the GLK2 gene causes tomatoes in development not to perform photosynthesis properly.
This gene is a transcription factor, and as such, acts as a conductor, giving orders to other genes, explained to Efe Rafael Fernandez, a researcher of the Research Council (CSIC), involved in this work.
In this case, he said the fruit cells that are developing organize chloroplasts for photosynthesis in presence of light.
The chloroplast is the plant cell organelle responsible for, among other things, the synthesis of sugars from CO2 and of light through the process of photosynthesis, he added.
According to Fernandez, most photosynthesis takes place in the chloroplasts of the leaves, and sugars that are produced there are transferred to the fruit, but at least 20% of the tomato's sugars could come from photosynthesis done directly in chloroplasts of the fruit.
And so the aspect of wild tomatoes and heirloom varieties present a gradation of green color to a more intense one at the top, are often rejected by the industry and transport.
Due to this, and a greater likelihood that the fruit cracks, in the mid-50´s a mutation was introduced in a gene called 'u' that provides fruits that ripen in auniformly red color, which is very attractive.
The results of this research identified the gene responsible for the mutation 'u' that produce tomatoes in a mature uniformly (without green shoulders) way and reveal what are the molecular basis that have affected the quality of the fruit.
This is because the fruits with the gene u possess a mutated version of the gene GLK2, which slows photosynthesis and implies a 20% reduction in sugars in tomatoes, detailed Fernandez.
This scientist warns that the lack of sugar is not the only thing that produces the "cardboard flavor" in tomatoes: Most commercial varieties also have altered genes for long-term post-harvest, that make tomatoes apparently mature, but have not actually finished maturing or accumulating substances that give its characteristic flavor.
This study was conducted with scientists from Argentina and the U.S., in addition to the Spanish Institute of Molecular and Cellular Biology (joint center of the Polytechnic University of Valencia and CSIC) and the Institute of Subtropical and Mediterranean Agriculture (CSIC and University of Malaga).