Victor Sack wrote:
> Flavor Is Price of Scarlet Hue of Tomatoes, Study Finds
> By GINA KOLATA
> International Herald Tribune
>
> Plant geneticists say they have discovered an answer to a near-universal
> question: Why are tomatoes usually so tasteless?
>
> Yes, they are often picked green and shipped long distances. Often they
> are refrigerated, which destroys their flavor and texture. But now
> researchers have discovered a genetic reason that diminishes a tomato's
> flavor even if the fruit is picked ripe and coddled.
>
> The unexpected culprit is a gene mutation that occurred by chance and
> that was discovered by tomato breeders. It was deliberately bred into
> almost all tomatoes because it conferred an advantage: It made them a
> uniform luscious scarlet when ripe.
>
> Now, in a paper published in the journal Science, researchers report
> that the very gene that was inactivated by that mutation plays an
> important role in producing the sugar and aromas that are the essence of
> a fragrant, flavorful tomato. And these findings provide a road map for
> plant breeders to make better-tasting, evenly red tomatoes.
>
> The discovery "is one piece of the puzzle about why the modern tomato
> stinks," said Harry Klee, a tomato researcher at the University of
> Florida in Gainesville who was not involved in the research. "That
> mutation has been introduced into almost all modern tomatoes. Now we can
> say that in trying to make the fruit prettier, they reduced some of the
> important compounds that are linked to flavor."
>
> The mutation's effect was a real surprise, said James J. Giovannoni of
> the United States Department of Agriculture Research Service, an author
> of the paper. He called the wide adoption of tomatoes that ripen
> uniformly "a story of unintended consequences."
>
> Breeders stumbled upon the variety about 70 years ago and saw commercial
> potential. Consumers like tomatoes that are red all over, but ripe
> tomatoes normally had a ring of green, yellow or white at the stem end.
> Producers of tomatoes used in tomato sauce or ketchup also benefited.
> Growers harvest this crop all at once, Dr. Giovannoni said, and "with
> the uniform ripening gene, it is easier to determine when the tomatoes
> are ripe."
>
> Then, about 10 years ago, Ann Powell, a plant biochemist at the
> University of California, Davis, happened on a puzzle that led to the
> new discovery. Dr. Powell, a lead author of the Science paper, was
> studying weed genes. Her colleagues had put those genes into tomato
> plants, which are, she said, the lab rats of the plant world. To Dr.
> Powell's surprise, tomatoes with the genes turned the dark green of a
> sweet pepper before they ripened, rather than the insipid pale green of
> most tomatoes today.
>
> "That got me thinking," Dr. Powell said. "Why do fruits bother being
> green in the first place?" The green is from chloroplasts,
> self-contained energy factories in plant cells, where photosynthesis
> takes place. The end result is sugar, which plants use for food. And,
> Dr. Powell said, the prevailing wisdom said sugar travels from a plant's
> leaves to its fruit. So chloroplasts in tomato fruit seemed
> inconsequential.
>
> Still, she said, the thought of dark green tomatoes "kind of bugged me."
> Why weren't the leaves dark green, too?
>
> About a year ago, she and her colleagues, including Dr. Giovannoni,
> decided to investigate. The weed genes, they found, replaced a disabled
> gene in a tomato's fruit but not in its leaves. With the weed genes, the
> tomatoes turned dark green.
>
> The reason the tomatoes had been light green was that they had the
> uniform ripening mutation, which set up a sort of chain reaction. The
> mutation not only made tomatoes turn uniformly green and then red, but
> also disabled genes involved in ripening. Among them are genes that
> allow the fruit to make some of its own sugar instead of getting it only
> from leaves. Others increase the amount of carotenoids, which give
> tomatoes a full red color and, it is thought, are involved in flavor.
>
> To test their discovery, the researchers used genetic engineering to
> turn on the disabled genes while leaving the uniform ripening trait
> alone. The fruit was evenly dark green and then red and had 20 percent
> more sugar and 20 to 30 percent more carotenoids when ripe.
>
> But were the genetically engineered tomatoes more flavorful? Because
> Department of Agriculture regulations forbid the consumption of
> experimental produce, no one tasted them.
>
> And, Dr. Giovannoni says, do not look for those genetically engineered
> tomatoes at the grocery store. Producers would not dare to make such a
> tomato for fear that consumers would reject it.
>
> But, Dr. Powell said, there is a way around the issue. Heirloom tomatoes
> and many wild species do not have the uniform ripening mutation. "The
> idea is to get the vegetable seed industry interested," Dr. Powell said.

Interesting--and no wonder I like heirloom varieties--and
especially the green (when ripe) tomatoes.

--
Jean B.