A LTR retrotransposon insertion leads to leafy phenotype in maize by elevating ZmOM66 expression

Area of Science:

• Plant genetics
• Molecular biology
• Maize genetics

Background:

• The genetic basis for maize (Zea mays) leaf development and flowering time is complex.
• Leafy (Lfy1) is a known dominant mutant exhibiting increased leaf number and delayed flowering, but the causative gene and mechanism remain elusive.

Purpose of the Study:

• To identify the gene responsible for the Lfy1 mutant phenotype in maize.
• To elucidate the molecular mechanism by which the Lfy1 mutation affects plant development and flowering time.

Main Methods:

• Cloning of the Lfy1 mutant gene.
• Analysis of gene expression patterns.
• Biochemical assays related to metabolism and circadian clock.

Main Results:

• A retrotransposon insertion in the Lfy1 mutant elevates the expression of the neighboring gene ZmOM66.
• ZmOM66 encodes a mitochondrial AAA+ ATPase whose overexpression affects starch degradation, metabolic intermediates, and circadian clock gene expression.
• Overexpression of ZmOM66 leads to decreased expression of key floral development genes, including photoperiod-regulated, integrator, and floral meristem identity genes.

Conclusions:

• The Lfy1 phenotype is caused by a retrotransposon-induced upregulation of ZmOM66.
• ZmOM66 plays a crucial role in regulating maize plant architecture, flowering transition, and metabolic homeostasis.