Antagonistic Genes Control Rice Growth

Researchers at the Carnegie Institution in the U.S., with colleagues from the Chinese Academy of Sciences, have found that a plant steroid prompts two genes to battle each other: one suppresses the other to ensure that leaves grow normally in rice and Arabidopsis. The results, published in the current issue of The Plant Cell, have important implications for understanding how to manipulate crop growth and yield. Zhi-Yong Wang and colleagues studied how brassinosteroids (BRs) promote leaf bending in rice and Arabidopsis. BRs affect two genes encoding transcription factors, proteins that turn other genes on or off.

The scientists found that in rice, activation of a gene called Increased Leaf Inclination1 (ILI1) causes leaf bending. Interestingly, the researchers found that the ILI1 protein also binds to another transcription factor, called IBH1, and inhibits its function. When there is too much ILI1 protein, the leaves bend excessively making the plant shaggy. When IBH1 level is high, cell growth is stopped at the joint and the rice is very erect, taking up less space. In normal rice plants the balance between ILI1 and IBH1 keeps growth in check.

Through a series of experiments, the researchers determined how the steroid and genes interact. They found that brassinosteroid oppositely regulate these genes — ILI1 was activated and IBH1 was repressed. As such, the steroid tips the balance between their protein products, ILI1 and IBH1, to initiate cell growth.

The original story is available at http://www.ciw.edu/news/antagonistic_genes_control_rice_growth Download the paper published by the Plant Cell at http://dx.doi.org/10.1105/tpc.109.070441