Copy number variation of TdDof controls solid-stemmed architecture in wheat

Area of Science:

• Plant genetics
• Molecular biology
• Agronomy

Background:

• Stem solidness is a crucial agronomic trait in durum and bread wheat, conferring resistance to the wheat stem sawfly.
• This trait is controlled by the SSt1 locus on chromosome 3B, but its molecular basis remains unknown.

Purpose of the Study:

• To identify the molecular identity and mechanism underlying stem solidness in wheat.
• To investigate the role of copy number variation in controlling this trait.

Main Methods:

• Map-based cloning to localize the TdDof gene within the SSt1 locus.
• Molecular analysis of TdDof copy number in hollow- and solid-stemmed cultivars.
• Gene deletion and transgenic overexpression experiments.
• Analysis of gene expression and programmed cell death (PCD) markers.

Main Results:

• The TdDof gene, encoding a DNA binding with one finger protein, was localized to the SSt1 locus.
• Hollow-stemmed wheat has one TdDof copy, while solid-stemmed wheat has multiple copies.
• TdDof copy number variation directly impacts stem solidness, with increased copies correlating with reduced PCD in pith cells.

Conclusions:

• Copy number variation of TdDof is the primary driver of stem solidness in wheat.
• TdDof negatively regulates programmed cell death, contributing to stem structural integrity.
• These findings offer potential for manipulating wheat stem development for agricultural benefits.