Endosperm Carbohydrates in Pseudostarchy and Extreme‐sugary Maize Inbreds During Kernel Development

Abstract

Evaluation of endosperm carbohydrates kernels of pseudostarchy, su1‐ref, and wild type inbreds will give us an understanding of pseudostarchy composition relative to wild type and should inform us on the underlying biochemistry of starch synthesis. A set of seven maize inbreds, fixed for the su1‐ref allele, were developed from two divergently selected maize populations. Three of these inbreds (pse) have a pseudostarchy kernel phenotype and four (esu) have a typical sugary kernel appearance. These seven inbreds were grown in two environments each with two field replications with the inbreds Ia453 su1‐ref and Ia453 Su1 (wild type). Polysaccharide composition was evaluated at 14, 21, 28, 35, and 50 (mature seed) days after pollination (DAP). Amylose, amylopectin, and sugar concentrations were measured on mature seed tissue. No major carbohydrate differences were identified among the pse inbreds and the Ia453 Su1 inbred. At all stages of development, the pse inbreds Wpse2 and Wpse3 contained water‐soluble polysaccharide (WSP) concentration similar to that of Ia453 Su1. The proportion of amylopectin in total starch in pse inbreds was not different from Ia453 Su1 indicating that amylopectin is being produced at wild type levels in pse inbreds. Pseudostarchy inbreds cannot be distinguished from Su1 maize inbreds based on carbohydrate concentrations during endosperm development. These results indicate that the biochemical mechanisms producing wild type starch without a wild type Su1 allele are activated early in development and sufficient debranching takes place to allow the formation of normal crystalline starch granules.