A molecular framework for grain number determination in barley.

Area of Science:

• Plant Molecular Biology
• Crop Science
• Genetics

Background:

• Flowering plants with indeterminate inflorescences often produce excess floral structures.
• Understanding the genetic regulation of floral development and grain yield is critical for crop improvement.

Purpose of the Study:

• To investigate the molecular mechanisms decoupling floral primordia initiation from grain maturation in barley (Hordeum vulgare L.).
• To identify key genes and pathways regulating floral growth, survival, and their impact on grain production.

Main Methods:

• Analysis of gene expression patterns, particularly focusing on barley CCT MOTIF FAMILY 4 (HvCMF4) in the inflorescence vasculature.
• Investigating the effects of HvCMF4 mutations on floral primordia survival, rachis greening, and plastidial energy supply.
• Exploring the interplay between light signaling, circadian clock, and vascular development in floral growth.

Main Results:

• Floral primordia initiation in barley is molecularly distinct from grain maturation.
• HvCMF4 orchestrates floral growth via light signaling, chloroplast development, and vascular programs, impacting primordia survival.
• HvCMF4 mutations lead to increased primordia death and pollination failure by reducing rachis greening and limiting energy supply.

Conclusions:

• HvCMF4 acts as a light sensory factor, coordinating floral initiation and survival with the vascular-localized circadian clock.
• Enhancing both floral primordia number and survival through beneficial HvCMF4 alleles positively impacts barley grain production.
• Findings provide crucial insights into the molecular basis of grain number determination in cereal crops.