A WOX5/7-SCRReciprocal Feedback Loop in Middle Cell Layer Drives Callus Proliferation

Area of Science:

• Plant biology
• Developmental biology
• Molecular genetics

Background:

• The middle cell layer of plant callus is vital for pluripotency and organ regeneration.
• Root apical stem cell regulators are known to maintain callus pluripotency, but their coordination in middle layer formation is unclear.

Purpose of the Study:

• To elucidate the functional coordination of root stem cell regulators in the middle callus layer.
• To identify the molecular mechanisms underlying callus proliferation and organ regeneration.

Main Methods:

• Investigated transcriptional activation between WOX5/7 and SCR in Arabidopsis callus.
• Analyzed protein complex formation between WOX5/7 and SCR.
• Performed transcriptomic analysis to identify co-regulated genes.

Main Results:

• Identified a reciprocal transcriptional activation between WOX5/7 and SCR in the middle callus layer.
• Demonstrated that WOX5/7 and SCR form protein complexes that enhance each other's transcriptional activity.
• Showed that WOX5/7 and SCR co-regulate cell cycle genes, impacting mitotic activity in mutants.

Conclusions:

• WOX5/7 and SCR establish a reciprocal positive feedback loop in the middle callus layer.
• This feedback loop promotes robust callus proliferation by enhancing cell cycle progression.
• The findings provide a molecular basis for understanding callus pluripotency and regeneration.