A New SNP in Rice Gene Encoding Pyruvate Phosphate Dikinase (PPDK) Associated with Floury Endosperm

Abstract

Rice varieties with suitable flour-making qualities are required to promote the rice processed-food industry and to boost rice consumption. A rice mutation, Namil(SA)-flo1, produces grains with floury endosperm. Overall, grains with low grain hardness, low starch damage, and fine particle size are more suitable for use in flour processing grains with waxy, dull endosperm with normal grain hardness and a high amylose content. In this study, fine mapping found a C to T single nucleotide polymorphism (SNP) in exon 2 of the gene encoding cytosolic pyruvate phosphate dikinase (cyOsPPDK). The SNP resulted in a change of serine to phenylalanine acid at amino acid position 101. The gene was named FLOURY ENDOSPERM 4-5 (FLO4-5). Co-segregation analysis with the developed cleaved amplified polymorphic sequence (CAPS) markers revealed co-segregation between the floury phenotype and the flo4-5. This CAPS marker could be applied directly for marker-assisted selection. Real-time RT-PCR experiments revealed that PPDK was expressed at considerably higher levels in the flo4-5 mutant than in the wild type during the grain filling stage. Plastid ADP-glucose pyrophosphorylase small subunit (AGPS2a and AGPS2b) and soluble starch synthase (SSIIb and SSIIc) also exhibited enhanced expression in the flo4-5 mutant.

Spatial distribution of proteins and metabolites in developing wheat grain and their differential regulatory response during the grain filling process

“…Interestingly, we found three isoforms of PPDK, all of them upregulated from 12 to 26 DAA (Table S11 ). Several proteomic studies reported that multiple isoforms of PPDK accumulate at high levels in the developing grain of cereals such as rice (Xu et al., 2008b ) and wheat (Ma et al., 2014b ), indicating that PPDK has an essential role in starch synthesis and energy supply during grain development (Wang et al., 2020 ). PPDK catalyzes the reversible conversion of pyruvate, ATP, and Pi to phosphoenolpyruvate (PEP), AMP, and PPi (Yu et al., 2016 ).…”

Genome-Wide Identification and Genetic Variations of the Starch Synthase Gene Family in Rice

“…Starch is the major carbohydrate in rice grains, of which approximately 18% is amylose and 82% is amylopectin [4]. The ratio of amylose to amylopectin plays an important role in the rice grain structure, appearance, and eating quality.…”

Temporal regulation of alternative splicing events in rice memory under drought stress

“…The gene ZmPPDK1 encodes an essential photosynthetic enzyme in maize, a C4 plant. By contrast, the rice ortholog OsPPDK1 (LOC_Os05g33570, Os05g0405000) has no role in photosynthesis but rather plays an important role in starch biosynthesis and during seed development ( Kang et al., 2005 ; Zhang et al., 2018 ; Wang et al., 2020 ).…”