A four-dimensional spatial transcriptome atlas of barley caryopsis development and germination

Area of Science:

• Plant biology
• Genomics
• Developmental biology

Background:

• Understanding gene expression patterns during plant development is crucial for crop improvement.
• Barley (Hordeum vulgare) is a vital global crop, yet its developmental gene expression landscape remains incompletely understood.

Purpose of the Study:

• To generate a comprehensive four-dimensional (4D) spatial gene expression atlas for barley grain development and germination.
• To investigate sub-tissue localization of biological activities, including energy metabolism and transport genes.
• To identify spatially specific transcription factors involved in barley seed development and germination.

Main Methods:

• Spatial transcriptomic analysis of serial sections of barley grain.
• Reconstruction of transcript abundance in three physical dimensions (xyz) with temporal kinetics.
• Trajectory analysis of aleurone tissue from development through germination.

Main Results:

• Detailed gene expression patterns across different tissues and developmental stages of barley grain were revealed.
• Heterogeneity in gene expression was observed across spatial axes (2D and 3D) and within identified clusters.
• Expression patterns of key genes were conserved across different barley varieties, validating the approach.

Conclusions:

• The 4D atlas provides a robust resource for understanding barley grain development and germination at a high resolution.
• Spatially specific transcription factors were identified, offering targets for future research in seed development.
• A public visualization browser facilitates exploration of 2D and 3D transcript abundance profiles.