BnaGSK3-BnaIDD16 module negatively regulates branch angle in Brassica napus

Area of Science:

• Plant Biology
• Genetics
• Agricultural Science

Background:

• Brassinosteroids (BRs) are crucial for plant height and leaf angle.
• The specific BR signaling mechanisms controlling branch angle remain unclear.

Purpose of the Study:

• To elucidate the molecular mechanism of brassinosteroid signaling in regulating branch angle in rapeseed (Brassica napus L.).
• To identify genetic variations for improving rapeseed plant architecture.

Main Methods:

• Isolation and map-based cloning of the rapeseed mutant dwarf and compact architecture 1 (dca1).
• Characterization of the BnaGSK3/DCA1 gene and its substrate BnaIDD16.A09.
• Analysis of natural variations in the BnaGSK3/DCA1 promoter.

Main Results:

• A gain-of-function mutation in BnaGSK3/DCA1 was identified as the cause of the dca1 phenotype.
• BnaGSK3/DCA1 phosphorylates BnaIDD16.A09, which activates auxin biosynthesis and controls branch angles during gravitropism.
• Two elite haplotypes of BnaGSK3/DCA1 with promoter variations were found, correlating with reduced branch angles and plant height.

Conclusions:

• The BnaGSK3/DCA1-BnaIDD16 module integrates BR signaling with auxin biosynthesis to control branch bending in rapeseed.
• These findings provide insights into rapeseed plant architecture regulation and offer targets for crop breeding.