Natures wonders: dandelion root protecton (Introduction)

by David Turell @, Wednesday, January 06, 2016, 02:08 (872 days ago) @ David Turell

The roots produce a substance which keeps away pests:

http://phys.org/news/2016-01-dandelion-latex-roots-insect.html

"In fields and meadows, the plant must fend off many herbivores, among them cockchafer larvae. The common cockchafer (Melolontha melolontha) spends the first three years of its life cycle underground as a grub feeding on the roots of different plants. One of its favorite foods is dandelion roots. Like many other plants, dandelions produce secondary metabolites to protect themselves against herbivores. Some of these defenses, such as terpenes and phenols, are of pharmaceutical interest and are considered promising anti-cancer agents. The most important dandelion metabolites are bitter substances which are especially found in a milky sap called latex, a substance found in almost ten percent of all flowering plants.

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"The researchers succeeded in identifying the enzyme and gene responsible for the formation of a precursor of TA-G biosynthesis, and so were able to engineer plants with lower TA-G. Roots of engineered plants with less TA-G were considerably more attacked by cockchafer larvae. The chemical composition of latex varies between different natural dandelion lines. A common garden experiment with different lines revealed that plants which produce higher amounts of TA-G maintained a higher vegetative and reproductive fitness when they were attached by cockchafer larvae. "For me, the biggest surprise was to learn that a single compound is really responsible for a defensive function," says Jonathan Gershenzon, the head of the Department of Biochemistry at the Max Planck Institute in Jena. "The latex of dandelions and other plants consists of such a mixture of substances that it didn't seem necessarily true that one chemical by itself had such a protective role against our study insect.'"

Comment: My usual question. How did evolution find the proper enzyme molecule to do the job? Hunt and peck? Enzymes are huge and complex molecules often with metal ions attached.


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