Identification of Rice Mutants with Altered Grain Alkali Digestion Trait

HyunJung Kim, Ralph Vin B. Imatong, Thomas H. Tai.

“...were prepared by manual husking and the grain length, width, and weight were measured. Length and width were determined using a VIBE QM3 Rice Analyzer ...”

ABSTRACT: “Gelatinization temperature (GT) is an important component of eating and cooking quality (ECQ) of rice. While direct measurement of GT is cumbersome, the alkali spreading value (ASV) test is a robust method commonly used to rapidly identify different GT types. In this study, we employed a modified ASV assay to screen a population of chemically-induced rice (cv. Kitaake) mutants (n = 405). Two mutant families, KDS-1623B and KDS-1824B, with significantly lower ASV (higher GT type) than wild type Kitaake (low GT type) were isolated. A nonsynonymous homozygous mutation in the isoamylase-type starch debranching enzyme gene ISA1 was identified in KDS-1623B. The mutation (G2709T) is predicted to change a valine at position 354 to a leucine in the α-amylase catalytic domain of ISA1. This result is consistent with the shrunken endosperm exhibited by KDS-1623B grains and the replacement of starch with phytoglycogen in isa1 (sugary-1) mutants. The altered ASV trait in KDS-1824B appears to be controlled by a single recessive mutation; however, the causal genetic lesion remains to be determined. These mutants will be useful resources for elucidating the complex nature of starch metabolism and its influence on ECQ of rice.”

Plant Breeding and Biotechnology, Vol 8, 2020. https://doi.org/10.9787/PBB.2020.8.1.19
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