A study led by researchers from the Consejo Superior de Investigaciones Científicas (CSIC) has identified a tomato gene that is involved in the accumulation of cesium and that plays a key role in the formation of seedless tomato fruits. This advance opens a door for the cultivation of this vegetable in soils with radioactive contamination, in addition to the development of seedless fruits.
“The study started from the hypothesis that a protein specialized in potassium transport, SlHAK5, constituted an important pathway for cesium to enter the tomato through the plant's roots. Thus, inactivating the SlHAK5 function could reduce the accumulation of cesium in the plant,” explained researcher Manuel Nieves-Cordones in an interview with Agrodiario.
“Once we obtained plants without the SlHAK5 function using the CRISPR-Cas technique, we tested them in CEBAS and verified that they accumulated less cesium than the plants that had active SlHAK5. The concentration of cesium in the fruits of the plants without the SlHAK5 function was 22 times lower than that of the plants with the SlHAK5 function,” he emphasized.
The researcher stated that the "danger that the accumulation of cesium in plants poses to human health arises from the ingestion of radioactive foods, for example, if they contain radioactive cesium. This can happen if plants have been grown in environments contaminated with radioactive cesium, such as in some areas near Fukushima or Chernobyl. Growing plants without the SlHAK5 function in areas where agriculture is limited due to the contamination of radioactive cesium in the soil (in Japan, for example), would be a reasonable alternative to produce tomatoes,” he stated.
Seedless tomatoes, an unexpected find
This research has also allowed the CSIC to obtain plants capable of producing tomatoes without seeds or with a very low quantity of them. “It was an unexpected find. We had clues about the function of SlHAK5 at the level of potassium and cesium transport, but we did not expect that by inactivating SlHAK5, the plants would stop producing seeds in the fruit. It appears that the lack of seeds is due to SlHAK5's importance in the plant's pollen viability. Thus, a plant lacking SlHAK5 has little viable pollen and cannot fertilize the ovules. If there is no fertilization, tomato plants develop fruits that lack seeds.”
“The advantage of the CRISPR-Cas system is that it can be applied to any plant. Therefore, SlHAK5 could be easily inactivated in any tomato variety, ” the researcher concluded.