Indian Scientists unfold the Puzzle of - How BR Regulates Cotyledon Unfolding

  • 13 Jul 2021

The scientists from the Indian Institute of Science Education and Research (IISER) Bhopal have identified a protein ‘BBX32’ that plays a critical role in plant growth regulation.

About ‘BBX32’

  • Control the Timing of Seedling Emergence: The protein ‘BBX32’ is a B-box (BBX) protein (B-box play an important role in plant growth and development) that helps provide leads to control the timing of seedling emergence.


  • As ‘BBX32’ help maximise proper seedling establishment, thereby enhancing crop yields in areas prone to heat waves during the Indian summer.
  • ‘BBX32’ helps in plant growth regulation by keeping its first leaves folded until they emerge out of the soil and thus provide crucial aid in the seedling establishment process.
  • This protein is activated in the darkness by a steroid hormone in plants called Brassinosteroid (BR).

About Brassinosteroid (BR) Hormone & Cotyledon Opening

  • The steroid hormone Brassinosteroid was found about 25 years ago - keeps cotyledons folded in the dark.
  • Cotyledon opening is a key morphological change that occurs in seedlings during de-etiolation - a process in flowering plants grown in partial or complete absence of light.
  • BR inhibits the opening of the cotyledons in darkness while light promotes their opening.

The Riddle

  • How BR regulates cotyledon unfolding has remained relatively unknown.

Indian Scientists’ Answer

  • Now, Indian scientists have that answer with ‘BBX32’.
  • ‘BBX32’ is regulated both by light and BR to the control cotyledon unfolding during the transition from dark to light.