Defective Kernel 1 (DEK1) is required for three-dimensional growth in Physcomitrella patens

Area of Science:

• Plant developmental biology
• Cellular morphogenesis
• Gene function analysis

Background:

• Cell division orientation is vital for plant development, particularly in transitions like moss gametophore formation.
• The conserved Defective Kernel 1 (DEK1) protein is implicated in positional cue perception for epidermal development in seed plants.

Purpose of the Study:

• To investigate the role of the conserved DEK1 gene in the moss Physcomitrella patens.
• To understand DEK1's function in controlling cell division orientation during morphogenetic transitions.

Main Methods:

• Generated a precise PpDEK1 deletion mutant (∆dek1) in Physcomitrella patens using gene targeting.
• Analyzed mutant phenotypes, including protonema growth and bud development.
• Complemented mutant phenotypes through overexpression of PpDEK1 cDNA and its calpain domain.

Main Results:

• The ∆dek1 mutant exhibited normal protonema growth but showed an excess of buds with abnormal cell divisions.
• Mutant buds arrested development, preventing three-dimensional growth.
• Overexpression of full-length PpDEK1 or its calpain domain rescued both observed mutant phenotypes.

Conclusions:

• The DEK1 protein is essential for regulating oriented cell divisions during moss gametophore development.
• These findings highlight DEK1's conserved morphogenetic role in plants.
• The P. patens system provides a platform for dissecting DEK1 domain structure-function relationships.