Allele-dependent barley grain beta-amylase activity

Area of Science:

• Plant Genetics and Breeding
• Agricultural Science
• Biochemistry

Background:

• Cultivated barley (Hordeum vulgare subsp. spontaneum) possesses valuable genetic diversity for malting quality.
• A high beta-amylase trait was previously identified in wild barley strains from Israel.
• This trait was introgressed into domesticated barley via backcrossing.

Purpose of the Study:

• To confirm the co-inheritance of the high beta-amylase trait with the beta-amy1 gene from the wild barley parent.
• To characterize beta-amy1 gene organization and identify distinct alleles in wild and domesticated barley.
• To investigate the genetic basis of high beta-amylase activity in barley grain.

Main Methods:

• Southern-blot analysis to track gene co-inheritance.
• Characterization of the beta-amy1 gene and its organization in various barley strains.
• DNA sequencing of isolated beta-amy1 alleles.

Main Results:

• The high beta-amylase trait in backcross lines is co-inherited with the beta-amy1 gene from Hordeum spontaneum.
• Three distinct beta-amy1 alleles were identified; two are present in modern barley, with one linked to good malting quality.
• A third allele, associated with high grain beta-amylase activity, was exclusively found in an Israeli wild barley strain.

Conclusions:

• Specific beta-amy1 alleles are linked to beta-amylase activity and malting quality in barley.
• A unique allele from Israeli wild barley confers high beta-amylase activity.
• Intron III sequences, including a 126-bp palindromic insertion, are implicated in allele-dependent beta-amylase expression.