Mapping and identifying candidate genes of the modifier of amylose extender 1 (mae1) mutation in maize (Zea mays L.)

Abstract

In maize (Zea mays L.), amylose extender 1 (ae1) mutants are associated with an increase in amylose content from 25 to 70%. A novel maize phenotype of completely shrunken, collapsed kernels was observed when backcrossing ae1 alleles into the food-grade inbred line cgx333. This novel mutation is recessive, epistatic to ae1 and appears to be due to the segregation of a single gene, modifier of amylose extender 1 (mae1). We hypothesize that the mae1 gene represents a yet unknown step in starch synthesis. In an ae1 background, mae1 results in smaller starch granules and a larger proportion of long amylopectin chains whereas in the presence of functional SBEIIb, mae1 does not have an effect on starch properties. Using a RIL population, the mae1 mutation was mapped by genotype-by-sequencing (GBS). The 81,018 polymorphic SNPs were narrowed down to 389 SNPs putatively associated with mae1, however a chromosomal location was not discerned.