Genetics of CM-proteins (A-hordeins) in barley

Area of Science:

• Plant genetics and molecular biology
• Protein characterization and inheritance
• Barley (Hordeum vulgare) research

Background:

• A-hordeins are major barley storage proteins, with CM-proteins forming their core components.
• Five CM-proteins (CMa-1, CMb-1, CMc-1, CMd-1, CMe-1) were identified, including a newly characterized CMe-1.
• Variability and inheritance patterns of these proteins are crucial for understanding barley genetics and breeding.

Purpose of the Study:

• To investigate the genetic variability of five CM-proteins across cultivated and wild barley accessions.
• To determine the inheritance patterns and chromosomal locations of genes encoding these CM-proteins.
• To explore the relationship between CM-protein accumulation and high-lysine barley mutants.

Main Methods:

• Analysis of protein variability in 38 Hordeum vulgare cultivars and 17 H. spontaneum accessions.
• Segregation analysis in a cross between H. spontaneum and H. vulgare to study inheritance.
• Utilizing wheat-barley addition lines to map gene locations on barley chromosomes.
• Investigating protein accumulation in high-lysine barley mutants (Riso 1508, Hiproly).

Main Results:

• CMa-1, CMc-1, and CMd-1 proteins showed invariant expression within cultivated barley.
• CMb-1/CMb-2 and CMe-1/CMe-2,2' variants were inherited codominantly as allelic variations.
• Genes CMa and CMc mapped to chromosome 1, CMb and CMd to chromosome 4, and CMe to chromosome 3.
• CMe-1 accumulation was completely blocked in Riso 1508 and partially in Hiproly mutants.

Conclusions:

• The study elucidates the genetic basis and chromosomal organization of key CM-proteins in barley.
• Findings support homoeology between barley chromosomes 1 & 4 and wheat chromosome groups 7 & 4.
• The CMe-1 protein's role in lysine content is highlighted by its absence in high-lysine mutants.