Variation in the wheat AP2 homoeologs, the genes underlying lodicule development

Area of Science:

• Plant genetics
• Molecular biology
• Crop science

Background:

• The barley gene HvAP2 regulates cleistogamous/non-cleistogamous flowering.
• Bread wheat possesses three homoeologous copies of HvAP2: TaAP2-A, TaAP2-B, and TaAP2-D, originating from the A, B, and D genomes.
• Lodicules swelling is crucial for non-cleistogamous flowering in wheat accessions.

Purpose of the Study:

• To investigate the natural variation in wheat AP2 homoeologs at nucleotide and polypeptide levels.
• To understand the conservation and functional implications of TaAP2 genes in wheat flowering.

Main Methods:

• Re-sequencing of wheat AP2 homoeologous genes (TaAP2-A, TaAP2-B, TaAP2-D).
• Analysis of nucleotide and polypeptide sequences for natural variation.
• Assessment of conservation across different wheat ploidy levels.

Main Results:

• Wheat AP2 homoeologs are highly conserved across different ploidy levels.
• No functional variants were detected at the critical miR172 targeting site in the sequenced wheat AP2 homoeologs.
• The sequences of TaAP2-A, TaAP2-B, and TaAP2-D are largely conserved.

Conclusions:

• Engineering cleistogamous wheat requires functional modification of all three TaAP2 homoeologs.
• The high conservation of TaAP2 genes suggests a robust regulatory mechanism for flowering in wheat.
• Targeting the miR172 site alone may not be sufficient for inducing cleistogamy.