ABERRANT PANICLE ORGANIZATION2 controls multiple steps in panicle formation through common direct-target genes

Area of Science:

• Plant Biology
• Developmental Biology
• Genetics

Background:

• Rice panicle formation involves a shift from vegetative to reproductive growth, marked by shoot apical meristem transformation.
• This transition includes increased meristem size, suppressed leaf growth (bract formation), and the generation of branch meristems.

Purpose of the Study:

• To investigate the role of ABERRANT PANICLE ORGANIZATION2 (APO2) in rice panicle development beyond its known function in branch formation.
• To identify genes regulated by APO2 and elucidate its regulatory mechanisms during the reproductive transition.

Main Methods:

• Analysis of APO2 function in regulating meristem size and bract suppression.
• Identification of direct and indirect target genes of APO2 through binding site analysis.
• Investigating APO2's control over downstream regulators of meristem cell proliferation and panicle development.

Main Results:

• APO2 is essential for increasing inflorescence meristem size and suppressing bract outgrowth.
• APO2 directly regulates known panicle development genes like SQUAMOSA PROMOTER BINDING PROTEIN LIKE14 and NECK LEAF1.
• A set of downstream genes were identified that mediate APO2's control over cell proliferation, bract suppression, and branching.

Conclusions:

• APO2 functions as a master regulator in rice panicle development.
• APO2 orchestrates multiple stages of the reproductive transition by directly controlling a network of downstream genes.