The scientists found 219 chemicals that affected the direction of plant growth due to gravity. Further screens reduced this number to 34, then down to 4 chemicals, which affected gravitropism and the movement of proteins through membranes within the plant cell. .
Only one of these resembled auxins, a plant-produced growth hormone involved in gravitropic responses, while two of the four did not work through known auxin pathways. One of the chemicals resembled pyocyanin a product of bacterial metabolism thought to target yeast cell membranes. With chemical genomics, the team could identify valuable genetic characteristics beyond the reach of conventional mutations, which are often lethal when present in essential genes such as those that encode many cellular membrane components. Combined with the formidable genetic mapping and information available from the Arabidopsis plant, chemical genomics is becoming a powerful new tool in plant biology. It is helping scientists better understand protein transportation and genetic signaling in a plant's cellular membrane system, which is essential to plant growth, yet is poorly understood.
The researchers can now use the compounds they have discovered to identify target pathways and proteins within the endomembrane system.
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Related Links
* Natasha Raikhel's faculty Web page: http://www.cepceb.ucr.edu/members/raikhel.htm
* Center for Plant Cell Biology at UCR: http://www.cepceb.ucr.edu/index.php
* Proceedings of the National Academy of Sciences: http://www.pnas.org/