Scientists have identified new gene modifications that can make tomatoes and eggplants grow bigger, which could help boost yields in developing countries.
Humans have been genetically engineering crops for thousands of years – but where the process used to involve simply selecting bigger or more fruitful plants to grow next year, in recent years scientists have been able to hack the genomes of crops and tweak specific genes to improve size, yield, hardiness, taste or texture.
To improve food security, researchers are currently mapping out the genomes of 22 crops in the nightshade genus, which includes tomatoes, potatoes, eggplants and peppers. In a new analysis, led by Johns Hopkins University and Cold Spring Harbor Laboratory, scientists realized that in these genomes, many gene sequences seem to duplicate over long time scales.
Exactly what role these genes played wasn’t clear, so the team investigated by tweaking the nightshade genomes. The researchers silenced either one or both copies of these duplicate genes, then grew the plants in the lab to see what happened. It turns out, they played important roles in traits like how long they took to flower, and the size and shape of the fruit that grew.
In one related plant – the forest nightshade – the team found that knocking out both copies of a duplicate gene called CLV3 turned the fruit all “weird, bubbly, disorganized.” But if just one copy was edited, the fruit grew larger than usual. In those edited plants, 30% of the fruit grew a third locule – the fleshy capsule that contains seeds. Wild-type plants normally had only two locules, growing a third just 5% of the time.
The fruit of the forest nightshade isn’t edible, but the team suspected that its food crop relatives might have similar genes at work. Sure enough, in the African eggplant genome they found a gene called SaetSCPL25-like, which directly controlled the number of locules the fruit grew. Better yet, when they edited these same genes into tomato plants, they also grew bigger fruit with more locules.
“This work shows the importance of studying many species together,” said Michael Schatz, co-lead author of the study. “We leveraged decades of work in tomato genetics to rapidly advance African eggplants, and along the way we found entirely new genes in African eggplants that reciprocally advance tomatoes. We call this 'pan-genetics,' and it opens endless opportunities to bring many new fruits, foods, and flavors to dinner plates around the world.”
Already, scientists have developed ways to genetically engineer tomatoes to improve their taste and nutritional value, change their size, speed up or slow down their ripening, and even turn them purple or make them spicy.
The research was published in the journal Nature.
Source: Johns Hopkins University
