Endosperm Carbohydrate Composition and Kernel Characteristics of shrunken2‐intermediate (sh2‐i/sh2‐i Su1/Su1) and shrunken2‐intermediate–sugary1‐reference (sh2‐i/sh2‐i su1‐r/su1‐r) in Sweet Corn

Abstract

The Shrunken2 (Sh2) gene in maize (Zea mays L.) codes for ADP‐glucose pyrophosphorylase. Corn homozygous for the shrunken2‐reference (sh2‐r) allele does not produce ADP‐glucose pyrophosphorylase, resulting in greatly reduced starch production and increased sugar in the endosperm. The shrunken2‐intermediate (sh2‐i) allele produces some enzyme and more starch than sh2‐r. The sugary1‐reference (su1‐r) allele results in endosperm with large amounts of water‐soluble polysaccharide (WSP), which gives sweet corn good mouth feel. The combination of endosperm WSP and sugar content determines sweet corn quality. We tested the hypothesis that double mutant sh2‐i/sh2‐i su1‐r/su1‐r results in increased amounts of endosperm WSP and sugar than sh2‐r/sh2‐r Su1/Su1, Sh2‐r/Sh2‐r su1‐r/su1‐r, or sh2‐r/sh2‐r su1‐r/su1‐r. Carbohydrate content was measured in kernels of near‐isogenic inbreds and hybrids of sh2‐i and sh2‐r in Su1 and su1‐r. The lines and hybrids were grown in field trials in 2009 and 2010. Carbohydrate content was determined using enzymatic procedures and quantified with a spectrophotometer. The WSP content in the double mutant sh2‐i su1‐r was greater than in sh2‐r and sh2‐r su1‐r. Sugar content in the double mutant sh2‐i su1‐r was greater than in su1‐r or sh2‐i. The WSP/starch ratio is an important determinant of mouth feel or texture. The sh2‐i/sh2‐i su1‐r/su1‐r hybrids had quality factors that exceed both sh2‐r and su1‐r commercial hybrids.

Transcriptome-wide association and prediction for carotenoids and tocochromanols in fresh sweet corn kernels

“…Contrary to sh2-R, the sh2-i mutant allele produces an intermediate phenotype rather than a fully shrunken kernel type (Giroux and Hannah 1994). It is included alongside homozygous mutant su1 alleles in some commercial sweet corn varieties to both maximize quality and improve seed germination (Dodson-Swenson and Tracy 2015). As inferred from the inbred line names (Supplemental Table S9), this is also the case with a subset of lines in our panel.…”

Transcriptome‐wide association and prediction for carotenoids and tocochromanols in fresh sweet corn kernels

“…Contrary to sh2‐R , the sh2‐i mutant allele produces an intermediate phenotype rather than a fully shrunken kernel type (Giroux & Hannah, 1994). It is included alongside homozygous mutant su1 alleles in some commercial sweet corn cultivars to both maximize quality and improve seed germination (Dodson‐Swenson & Tracy, 2015). As inferred from the inbred line names (Supplemental Table S9), this is also the case with a subset of lines in our panel.…”

Selection indexes for agronomic and chemical traits in segregating sweet corn populations

“…sacharatta) is a special type of corn that has a greater concentration of sugars in the grains in relation to common corn. This characteristic is ruled by one or more genes of recessive allele, such as genes shrunken and sugary, which inhibit the conversion of sugars into starch in the endosperm, giving great palatability (Dodson-Swenson & Tracy, 2015). In addition, sweet corn is intended solely for human consumption, mainly after industrial processing (Pereira Filho & Teixeira, 2016).…”