Non-GMO potato lines with an altered starch biosynthesis pathway confer increased-amylose and resistant starch properties

The lack of a gene marker directly affecting starch biosynthesis in the potato tuber is documented. The absence of a 454 bp amplified fragment length polymorphism (AFLP) Solanum tuberosum fragment was identified in the wild potato species Solanum sandemanii and its absence results in a combined increased-amylose/high-sugar tuber chemotype. The trait is recessive, termed IAm (Increased Amylose) and was transferred to modern tetraploid S. tuberosum potato cultivars by marker-assisted crossing. Compared to controls, IAm plants had a larger number of stems and air exposed stolons, their tubers were smaller, elongated, and they were irregularly shaped. IAm starch had 28-59% higher amylose content than control starch, the starch granules were small and grossly misshaped, they had reduced crystallinity, swelling, and viscosity, reduced in vitro digestion rates with increased resistant starch fraction. The primary gene(s) responsible for the IAm phenotype is not known, but increased granule-associated phosphorylase (Pho1) and reduced starch synthase (SS) protein and enzyme activity in the IAm plants might explain the effects on starch structure. The data support the establishment of non-genetically modified crops with health-related slowly digestible carbohydrate.