Using the dominant mutation gene Ae1-5180 (amylose extender) to develop high-amylose maize

Maize amylose is a type of high value-added starch used for medical, food, and chemical applications. Mutations in the starch branching enzyme (SBEIIb), with recessive ae (amylose extender) and dominant Ae1-5180 alleles, are the primary way to improve maize endosperm amylose content (AC). However, studies on Ae1-5180 mutation are scarce, and its roles in starch synthesis and breeding potential are unclear. We found that the AC of the Ae1-5180 mutant was 47.23%, and its kernels were tarnished and glassy and are easily distinguished from those of the wild type (WT), indicating that the dominant mutant has the classical characteristics of the ae mutant. Starch granules of Ae1-5180 became smaller, and higher in amount with irregular shape. The degree of amylopectin polymerisation changed to induce an increase in starch thermal stability. Compared with WT, the activity of granule-bound starch synthase and starch synthase was higher in early stages and lower in later stages, and other starch synthesis enzymes decreased during kernel development in the Ae1-5180 mutant. We successfully developed a marker (mu406) for the assisted selection of 17 Ae1-5180 near isogenic lines (NILs) according to the position of insertion of the Mu1 transposon in the SBEIIb promoter of Ae1-5180. JH214/Ae1-5180, CANS-1/Ae1-5180, CA240/Ae1-5180, and Z1698/Ae1-5180 have high breeding application potential with their higher AC (> 40%) and their 100-kernel weight decreased to < 25% compared to respective recurrent parents. Therefore, using the dominant Ae1-5180 mutant as a donor can detect the kernel phenotype and AC of Ae1-5180-NILs in advance, thereby accelerating the high-amylose breeding process.

The online version contains supplementary material available at 10.1007/s11032-022-01323-7.