Scientists Find Mechanism for Master Switch of Plant Growth

Scientists from RIKEN in Japan and their colleagues from the University of Tokyo have discovered a master switch that controls plant growth. The group discovered a new cell mechanism, centered around a protein called BSS1/BZR1, that allows precise control of plant height by regulating plant brassinosteroid signaling. The group used mutant plants and Brz, a brassinosteroid biosynthesis inhibitor, to study the mechanism.

They focused on BIL1, a master switch that regulates some 3,000 genes, making up 10% of the 30,000 genes of the plant Arabidopsis. They discovered a protein called BSS1, which interacts with BIL1 to negatively regulate brassinosteroid signaling. As they examined the movement of BSS1 in brassinosteroid-deficient cells, they discovered that the creation of a complex of large proteins suppressed plant stem elongation. They determined the detailed mechanism through which BIL1 is captured by the formation of this protein complex with BSS1, and discovered that its breakdown by brassinosteroids seems to allow BIL1 to move into the nucleus.

It appears that the interplay between BSS1 and brassinosteroids leads to the formation of the complex, resulting in shortened plant height, while conversely the breakdown of the complex leads to stem elongation and greater height. Takeshi Nakano of the RIKEN Center for Sustainable Resource Science (CSRS), who led the study said, "Based on these findings, we hope to be able to develop technologies to allow us to freely control the plant height of plant biomass and useful crops, and contribute to reducing CO₂ in the atmosphere."

For more information, read: http://www.riken.jp/en/pr/press/2015/20150207_1/.