Transcript profiling of crown rootless1 mutant stem base reveals new elements associated with crown root development...

Area of Science:

• Plant Biology
• Genetics
• Molecular Biology

Background:

• Crown roots (CR) form the primary post-embryonic root system in rice.
• The crown rootless1 (crl1) mutant lacks CR primordia initiation.
• CROWN ROOTLESS1 (CRL1) is an auxin-induced transcription factor regulating CR development.

Purpose of the Study:

• To identify genes involved in rice crown root development.
• To understand the regulatory network controlled by CRL1.
• To determine genes directly regulated by CRL1 and auxin.

Main Methods:

• Comparative gene expression profiling of crl1 mutant and wild-type rice.
• Analysis of gene expression kinetics following exogenous auxin treatment.
• Identification of CRL1-dependent auxin-responsive genes.

Main Results:

• Global gene expression analysis revealed significant down- and up-regulation in the crl1 mutant.
• Most differentially expressed genes were indirectly affected by the absence of CR formation.
• Identified three CRL1-dependent auxin-responsive genes: FAS1/FSM, GTE4, and MAP.

Conclusions:

• Differential gene regulation in crl1 is largely an indirect consequence of absent CR.
• FAS1/FSM, GTE4, and MAP are likely directly regulated by CRL1 and auxin.
• These identified genes are involved in polarized cell growth, cell cycle regulation, and chromatin remodeling, suggesting their role in CR initiation.