Impacts of proximal internode elongation on floral degeneration, lodging resistance and community performance in barley

• Applicant: Dr. Yongyu Huang
• Subject Area: Plant Breeding and Plant Pathology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535680915

In most cereal crops such as barley (Hordeum vulgare L.), the shoot is composed of several internodes. The elongation of each internode (source organ) first starts from the proximal end of the shoot axis, during which the inflorescence (sink organ) is also undergoing strong cellular activity, including floral organ initiation and differentiation. This suggests that both proximal internodes and inflorescences at early developmental stages represent high energy demanding organs that may compete with each other for resource allocation. Particularly, in a community environment of high planting density, proximal internodes usually suffer from intensified canopy shades compared to the distal ones, and are also highly relevant to lodging resistance because the bending of the shoot during lodging typically occurs at the proximal end. Despite its functional importance, genetic studies on proximal internode have been challenging due to the substantial variations of internode number. I found that this problem can be partially overcame by applying a simple moving average strategy, allowing further genetic gains on this largely underexplored functional trait. In this project proposal, I aim to understand the molecular genetic basis of proximal internode elongation and its impact on grain yield formation under contrasting planting densities. To this end, I will: (1) conduct multi-omics (transcriptome, metabolism and phytohormone) analysis of proximal internode elongation under shade using barley genotypes with contrasting proximal internode lengths and floral survival; (2) reconstruct the 3D vascular anatomical features connecting the developing inflorescences and proximal internodes using serial sectioning; (3) in parallel, I will conduct a three-year’s field trial, in which a barley natural population and a double-diploid (DH) bi-parental mapping population will both be exposed to different planting density environments that recapitulate natural shading dynamics. This will allow the investigation of how proximal internodes are phenotypically and genetically coupled to individual floral survival and community performance; (4) finally, using genome-editing techniques such as CRISPR/Cas9, candidate genes for proximal internode elongation will be functionally validated. Integrating those data sets will allow the redesign of plant architectures that minimize source – sink competition, thereby benefiting community performance.

• DFG Programme: Independent Junior Research Groups