Conditional knockdown of gene expression in plants via 3' UTR editing.

Area of Science:

• Plant molecular biology
• Genome editing technologies
• Crop molecular breeding

Background:

• Spatiotemporal gene knockdown is a key goal in molecular breeding.
• Endogenous microRNAs (miRNAs) regulate gene expression through target recognition.
• Existing methods for gene knockdown lack precise spatiotemporal control.

Purpose of the Study:

• To develop a novel method for precise spatiotemporal gene suppression using genome editing.
• To investigate the feasibility of creating artificial miRNA-dependent regulatory circuits.
• To validate the efficacy of miRNA-mediated, in-locus knockdown (MiRKD) in rice.

Main Methods:

• Analysis of rice miRNA expression profiles to select endogenous miRNAs.
• Integration of miRNA target sequences into the 3' untranslated region (UTR) of target genes via genome editing.
• Transient assays and generation of stably-edited rice plants to assess gene expression levels.
• Utilizing GID1 as a target gene to evaluate different miRNA knock-ins.

Main Results:

• In-locus incorporation of miRNA targets into the 3' UTR effectively reduced target gene expression spatiotemporally.
• Knockin of miR156a target resulted in a 97% constitutive reduction of GID1 expression.
• Knockin of miR396c target specifically reduced GID1 expression in shoots.
• Knockin of miR528 target led to a 95% temporal decrease in GID1 expression under long-day conditions.

Conclusions:

• MiRNA-mediated, in-locus knockdown (MiRKD) is a viable and convenient approach for crop breeding.
• This method allows for conditional gene suppression by leveraging endogenous miRNA expression patterns.
• Genome editing combined with miRNA targeting offers precise control over gene function in plants.