The IQ67-domain protein IQD1 regulates fruit shape through complex multiprotein interactions in pepper (Capsicum...

Area of Science:

• Plant genetics
• Crop improvement
• Molecular biology

Background:

• Natural genetic variation is crucial for enhancing crop traits.
• Understanding the genetic basis of fruit shape variation is vital for pepper breeding.

Purpose of the Study:

• Identify genes controlling pepper fruit shape.
• Elucidate the molecular mechanisms underlying fruit shape regulation.

Main Methods:

• Conventional genetic mapping to identify quantitative trait loci (QTL).
• Gene expression analysis (reduced expression and heterologous overexpression).
• Protein-protein interaction studies and analysis of downstream gene expression.

Main Results:

• A novel gene, CaIQD1, was identified as a QTL for pepper fruit length-width ratio.
• Reduced CaIQD1 expression leads to short, wide peppers; overexpression in tomato yields narrower fruits.
• CaIQD1 interacts with CaOFP20, CaTRM-like, CaCaM7, CaMAP70-2, and CaKLCR1, affecting cell proliferation, expansion, and microtubule dynamics.

Conclusions:

• CaIQD1 is a central regulator of pepper fruit shape, acting through a module involving CaTRM-like-CaOFP20.
• The CaIQD1 pathway's regulation of fruit shape involves calcium-mediated changes in microtubule dynamics.
• This study reveals a conserved regulatory pathway for fruit shape control in plants.