Reprogramming of microspore fate via BBM-BAR1 for highly efficient in vivo haploid induction

Area of Science:

• Plant reproductive biology
• Molecular genetics
• Crop science

Background:

• Haploid induction (HI) via stress-treated microspore culture is a long-standing technique for plant breeding.
• The molecular mechanisms governing microspore reprogramming for androgenesis remain largely unknown.
• Current HI methods often require specific stress treatments, limiting efficiency and applicability.

Purpose of the Study:

• To elucidate the molecular mechanisms controlling microspore fate transition during androgenesis.
• To identify key genetic factors that can induce androgenesis without stress treatment.
• To develop a novel, efficient in vivo haploid induction method for diverse crops.

Main Methods:

• Microspore-specific expression of BABY BOOM (BBM) in tobacco and rice.
• Identification and characterization of BBM-activated Androgenesis Regulator 1 (BAR1).
• Assessing the role of BBM and BAR1 in reprogramming microspore development and inducing androgenesis.

Main Results:

• Microspore-specific BBM expression successfully induced in vivo androgenesis in tobacco and rice, bypassing stress requirements.
• BAR1 was identified as a novel downstream effector of BBM, crucial for microspore reprogramming.
• Both BBM and BAR1 demonstrated the ability to replace stress treatments in triggering androgenesis.

Conclusions:

• A conserved regulatory module involving BBM and BAR1 governs plant androgenesis.
• This study presents a transformative, stress-free approach for highly efficient in vivo haploid induction.
• The findings pave the way for improved breeding strategies and crop genetic advancements across various species.