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Crop Biotech Update

Biologists Study Genetic Mechanism Involved in Shade Responses of Grasses

August 5, 2011

Branching architecture of plants depends on both genotype and the environment. Tillers, branches that grow out on the base of grass plants, are suppressed when the plants are under shade. Plant biologists at the Cold Spring Harbor Laboratory in the U.S. conducted a study to investigate the genetics of how maize responds to shading during growth.

David Jackson and colleagues isolated grassy tillers 1 (gt1) gene from maize through positional cloning and found that it codes for another gene that confers lateral bud dormancy and inhibits elongation of lateral ear branches. Shading stimulates the expression of gt1. It was also found to be dependent on the activity of another gene called teosinte branched 1 (tb1), which controls tillering and lateral branching. After sequencing gt1 from different lines of model maize and wild teosinte, it was discovered that gt1 was selected during domestication to improve plant architecture.

These findings provide evidences that reduced branching and shade avoidance are related responses of grasses to the environment.

Subscribers of the Proceedings of the National Academy of Sciences of the United States of America may view the full paper at http://www.pnas.org/content/early/2011/07/27/1102819108.full.pdf+html.