Maize ZmDLR2/BRU1 Is Required for Lateral Root Primordium Emergence by Participating in DNA Repair

Area of Science:

• Plant Biology
• Genetics
• Molecular Biology

Background:

• Lateral roots (LRs) are vital for maize water and nutrient uptake, influencing yield and stress resilience.
• Understanding LR formation mechanisms is key to improving maize cultivation.

Purpose of the Study:

• To investigate the molecular basis of impaired lateral root development in the maize mutant defective in lateral root 2-1 (dlr2-1).
• To elucidate the role of ZmDLR2 in DNA repair, lateral root formation, and overall plant productivity.

Main Methods:

• Phenotypic analysis and RNA-sequencing of the dlr2-1 mutant.
• Positional cloning and allelic analysis to identify the causative mutation.
• Comet assays to assess DNA damage and fragmentation.
• Exogenous treatment with genotoxic agents.

Main Results:

• The dlr2-1 mutant exhibits defective cell proliferation in lateral root primordia (LRP) and activated DNA damage response.
• A missense mutation in ZmDLR2 (ZmDLR2^L1035Q) was identified as the cause of LR defects.
• ZmDLR2 is a maize orthologue of Arabidopsis BRU1, involved in DNA damage repair.
• The mutation leads to increased DNA fragmentation, reduced LR development, impaired plant height, smaller kernel size, and lower yield.

Conclusions:

• ZmDLR2 is indispensable for DNA repair, crucial for initiating lateral root primordia and subsequent LR formation.
• Dysfunction of ZmDLR2 activates the DNA damage response, inhibiting cell proliferation and compromising maize productivity.
• The study highlights ZmDLR2's role in maintaining genomic integrity for optimal plant development and yield.