Scientists identify gene that dramatically boosts yield in tomatoes

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Washington, March 29 (ANI): A team of scientists has identified a gene that pushes hybrid tomato plants to spectacularly increase yield.

The yield-boosting power of this gene, which controls when plants make flowers, works in different varieties of tomato, and crucially, across a range of environmental conditions.

"This discovery has potential to have a significant impact on both the billion-dollar tomato industry, as well as agricultural practices designed to get the most yield from other flowering crops," said Zach Lippman from Cold Spring Harbor Laboratory (CSHL), one of the three authors on the study.

The study is co-authored by Israeli scientists Uri Krieger and Professor Dani Zamir.

The team made the discovery while hunting for genes that boost hybrid vigor, a revolutionary breeding principle that spurred the production of blockbuster hybrid crops like corn and rice a century ago.

Hybrid vigor, also known as heterosis, is the miraculous phenomenon by which intercrossing two varieties of plants produces more vigorous hybrid offspring with higher yields.

First observed by Charles Darwin in 1876, heterosis was rediscovered by CSHL corn geneticist George Shull 30 years later, but how heterosis works has remained a mystery.

Shull's studies suggested that harmful, vigor-killing gene mutations that accumulate naturally in every generation are exposed by inbreeding, but hidden by crossbreeding.

"But there is still no consensus as to what causes heterosis," said Lippman.

"Another theory for heterosis, supported by our discovery, postulates that improved vigor stems from only a single gene - an effect called "superdominance" or "overdominance"," he added.

To find overdominant genes, the team developed a novel approach by turning to a vast tomato "mutant library" - a collection of 5,000 plants, each of which has a single mutation in a single gene that causes defects in various aspects of tomato growth, such as fruit size and leaf shape.

Selecting a diverse set of mutant plants, most of which produced low yield, the team crossed each mutant with its normal counterpart and searched for hybrids with improved yield.

Among several cases, the most dramatic example increased yield by 60 percent.

This hybrid, the team found, produced greater yields because there was one normal copy and one mutated copy of a single gene that produces a protein called florigen.

This protein, touted as the breakthrough discovery of the year in 2005 in Science magazine, instructs plants when to stop making leaves and start making flowers, which in turn produce fruit.

"Our results indicate that breeding with hybrid mutations could prove to be a powerful new way to increase yields, not only in tomato, but all crops," said Lippman. (ANI)

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