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Health

Tomatoes!

Gene ExpressionBy Razib KhanJune 29, 2012 8:19 AM

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800px-Bright_red_tomato_and_cross_section02.jpg

This story in The New York Times, Flavor Is Price of Scarlet Hue of Tomatoes, Study Finds, is pretty cool:

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 paper, Uniform ripening Encodes a Golden 2-like Transcription Factor Regulating Tomato Fruit Chloroplast Development:

Modern tomato (Solanum lycopersicum) varieties are bred for uniform ripening (u) light green fruit phenotypes to facilitate harvests of evenly ripened fruit. U encodes a Golden 2-like (GLK) transcription factor, SlGLK2, which determines chlorophyll accumulation and distribution in developing fruit. In tomato, two GLKs—SlGLK1 and SlGLK2—are expressed in leaves, but only SlGLK2 is expressed in fruit. Expressing GLKs increased the chlorophyll content of fruit, whereas SlGLK2 suppression recapitulated the u mutant phenotype. GLK overexpression enhanced fruit photosynthesis gene expression and chloroplast development, leading to elevated carbohydrates and carotenoids in ripe fruit. SlGLK2 influences photosynthesis in developing fruit, contributing to mature fruit characteristics and suggesting that selection of u inadvertently compromised ripe fruit quality in exchange for desirable production traits.

Genetics for better living! But I had no idea that the laws in regards to mutant varieties were so retrograde:

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.

Image credit: Fir0002/Flagstaffotos, GFDL v1.2.

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