Inducement and identification of an endosperm mutant in maize

Abstract

To screen a workable dosage combination of gamma-ray and NaN₃ for mutation inducement, maize calli were treated with different dosages of ⁶⁰Co gamma-ray and NaN₃. Mutant lines were derived from the regenerated plants. The results indicate that the combination of 20 Gy of gamma-ray and 1 mmol/L of NaN₃ is the most effective for mutation inducement of maize calli. Three endosperm mutant lines with “super sweet” phenotype were derived from the mutated offspring. By complementation test and DNA sequence analysis, their mutation site was found in exon 14 of gene sh2 that encodes adenosine diphosphate glucose pyrophosphorylase. For their highly consistent phenotypes of agronomic characteristics and distinguished molecular mechanism to the previous mutants of gene sh2, these three mutant lines are regarded as a novel multiallelic mutant of gene sh2.

Key words: Maize, endosperm mutant, sh2 gene.