Transcriptome Profiling Predicts New Genes to Promote Maize Callus Formation and Transformation

Area of Science:

• Plant Molecular Biology
• Genomics
• Biotechnology

Background:

• Maize transformation relies on embryonic callus formation from scutellum cells.
• Limited genes regulating maize callus induction have been identified previously.

Purpose of the Study:

• To identify genes involved in early maize callus induction.
• To understand the molecular mechanisms underlying auxin-induced callus formation.

Main Methods:

• High-throughput RNA sequencing of maize embryos cultured with or without 2,4-dichlorophenoxyacetic acid (auxin) over 8 days.
• Analysis of gene expression patterns and identification of transcription factors.
• Overexpression of candidate genes in maize inbred lines.

Main Results:

• 7,525 genes were induced by auxin, with significant clusters related to signal transmission and binding functions.
• 659 transcription factors from 51 families were identified among induced genes.
• ZmBBM2, an AP2 transcription factor, was rapidly induced by auxin and promoted callus induction and proliferation.

Conclusions:

• Comprehensive transcriptomic analysis provides insights into early molecular regulations of maize callus induction.
• ZmBBM2 is a key regulator that promotes callus formation and proliferation in maize.
• Findings are valuable for identifying regulators of callus formation and improving maize transformation.