Department of Plant Bioscience, College of Natural Resources and Life Science, Pusan National University, Miryang, 50463, Republic of Korea.
National Institute of Crop Science, Rural Development Administration, Jeonju, 54874, Republic of Korea.
Mol Genet Genomics. 2018 Oct;293(5):1151-1158. doi: 10.1007/s00438-018-1446-1. Epub 2018 May 9.
Pyruvate orthophosphate dikinase (PPDK) is a component of glycolysis to mediate endosperm energy charge by adjusting the ratio of ATP to ADP and AMP that proposed to balance the flow of carbon into starch, protein, fatty acid and amino acid biosynthesis. However, these were inconsistent with the first report of a T-DNA insertional knockout mutant of the rice PPDK gene (flo4) showed that rice with inactivated PPDK gene failed to produce a opaque seeds. Therefore, the PPDK might have multifaceted functions in grain filling stage, which in some ways might depend on the direction of the reversible catalysis. Suweon 542 is a rice (Oryza sativa L.) mutant developed from Oryza sativa ssp. japonica cv. Namil. Suweon 542 has a milky-white floury endosperm suitable for dry filling, with low starch damage, low grain hardness, and fine flour particle size. The mutant locus on chromosome 5 controls the floury endosperm phenotype of Suweon 542. Fine mapping of this locus is required for efficient breeding of rice germplasm suitable for dry milling. In this study, whole genome of Suweon 542 and Milyang 23 were re-sequenced using Illumina HiSeq 2500. Co-segregation analysis of F family populations derived from Suweon 542/Milyang 23 was performed using eight CAPS markers and phenotypic evaluation of the endosperm. The target region was mapped to a 33 kb region and identified to encode cytosolic pyruvate orthophosphate dikinase protein (cyOsPPDK). A G→A SNP in exon 8 of cyOsPPDK resulting in a missense mutation from Gly to Asp at amino acid position 404 was responsible for the floury endosperm of Suweon 542. qRT-PCR experiments revealed that FLO4-4 was expressed to a considerably higher level in Suweon 542 than in Namil during the grain filling stage. Overall, fine mapping of FLO4-4 and candidate gene analysis provided further insight into the floury endosperm of rice, and reveal a novel SNP in cyOsPPDK gene can affect the floury endosperm phenotype through active PPDK gene during grain filling stage.
丙酮酸-5-磷酸二激酶（PPDK）是糖酵解的一个组成部分，通过调节 ATP 与 ADP 和 AMP 的比例来调节胚乳能量电荷，从而提出平衡碳流入淀粉、蛋白质、脂肪酸和氨基酸生物合成的设想。然而，这些与水稻 PPDK 基因（flo4）的 T-DNA 插入缺失突变体的第一个报告不一致，该报告表明，失活 PPDK 基因的水稻无法产生不透明的种子。因此，PPDK 在灌浆阶段可能具有多方面的功能，在某些方面可能取决于可逆催化的方向。Suweon 542 是一种从粳稻品种 Namil 中开发的水稻（Oryza sativa L.）突变体。Suweon 542 的乳白色粉质胚乳适合干法填充，淀粉损伤低，籽粒硬度低，面粉粒径细。第 5 号染色体上的突变位点控制 Suweon 542 的粉质胚乳表型。该位点的精细定位对于高效培育适合干法加工的水稻种质资源是必要的。在这项研究中，使用 Illumina HiSeq 2500 对 Suweon 542 和 Milyang 23 进行了全基因组重测序。利用 8 个 CAPS 标记对 Suweon 542/Milyang 23 的 F 家族群体进行共分离分析，并对胚乳进行表型评价。目标区域被映射到 33kb 区域，并鉴定为编码细胞质丙酮酸-5-磷酸二激酶蛋白（cyOsPPDK）。cyOsPPDK 外显子 8 中的 G→A SNP 导致第 404 位氨基酸从甘氨酸突变为天冬氨酸，导致 Suweon 542 的粉质胚乳。qRT-PCR 实验表明，在灌浆阶段，FLO4-4 在 Suweon 542 中的表达水平明显高于 Namil。总体而言，FLO4-4 的精细定位和候选基因分析进一步深入了解了水稻的粉质胚乳，并揭示了 cyOsPPDK 基因中的一个新 SNP 可以通过灌浆阶段活跃的 PPDK 基因影响粉质胚乳表型。
