New starch phenotypes produced by TILLING in barley

Area of Science:

• Agricultural Science
• Molecular Biology
• Biochemistry

Background:

• Barley grain starch comprises amylose and amylopectin, packed into distinct A- and B-granules.
• Starch granule structure and composition are crucial for nutritional value and industrial uses.
• Enzymes controlling starch synthesis and structure are key targets for crop improvement.

Purpose of the Study:

• To utilize the TILLING approach to identify novel mutations in barley starch metabolism genes.
• To analyze the impact of these mutations on starch granule characteristics.

Main Methods:

• Application of the Targeting-Induced Local Lesions IN Genomes (TILLING) method on the barley TILLMore population.
• Identification of new alleles in five key starch metabolism genes: BMY1, GBSSI, LDA1, SSI, and SSIIa.
• Analysis of starch granule size, crystallinity, and amylose/amylopectin content in M3 mutant lines.

Main Results:

• Seven mutant lines exhibited altered starch features compared to wild-type barley.
• Mutations in GBSSI, SSI, and SSIIa genes significantly affected amylose/amylopectin ratio, granule size distribution, and crystal packing.
• Mutations in LDA1 and SSIIa suggested roles in granule initiation and A-granule size determination.

Conclusions:

• The TILLING approach is effective for discovering new alleles in barley starch metabolism genes.
• Identified mutations confer novel physicochemical properties to barley starch, with potential for nutritional and industrial applications.