Hashimoto Shumpei, Okada Satoshi, Araki-Nakamura Satoko, Ohmae-Shinohara Kozue, Miura Kotaro, Kawaguchi Hideo, Ogino Chiaki, Kasuga Shigemitsu, Sazuka Takashi
Bioscience and Biotechnology Center, Nagoya University, Nagoya, Japan.
Faculty of Bioscience and Biotechnology, Fukui Prefectural University, Fukui, Japan.
Front Plant Sci. 2023 Feb 13;14:1114935. doi: 10.3389/fpls.2023.1114935. eCollection 2023.
Sorghum is the fifth most important cereal crop. Here we performed molecular genetic analyses of the 'SUGARY FETERITA' (SUF) variety, which shows typical sugary endosperm traits (e.g., wrinkled seeds, accumulation of soluble sugars, and distorted starch). Positional mapping indicated that the corresponding gene was located on the long arm of chromosome 7. Within the candidate region of 3.4 Mb, a sorghum ortholog for maize () encoding a starch debranching enzyme ISA1 was found. Sequencing analysis of in SUF uncovered nonsynonymous single nucleotide polymorphisms (SNPs) in the coding region, containing substitutions of highly conserved amino acids. Complementation of the rice () mutant line with the gene recovered the sugary endosperm phenotype. Additionally, analyzing mutants obtained from an EMS-induced mutant panel revealed novel alleles with phenotypes showing less severe wrinkles and higher Brix scores. These results suggested that was the corresponding gene for the sugary endosperm. Expression profiles of starch synthesis genes during the grain-filling stage demonstrated that a loss-of-function of affects the expression of most starch synthesis genes and revealed the fine-tuned gene regulation in the starch synthetic pathway in sorghum. Haplotype analysis using 187 diverse accessions from a sorghum panel revealed the haplotype of SUF showing severe phenotype had not been used among the landraces and modern varieties. Thus, weak alleles (showing sweet and less severe wrinkles), such as in the abovementioned EMS-induced mutants, are more valuable for grain sorghum breeding. Our study suggests that more moderate alleles ( produced by genome editing) should be beneficial for improving grain sorghum.
高粱是第五大重要的谷类作物。在此，我们对‘甜费泰瑞塔’（SUF）品种进行了分子遗传学分析，该品种表现出典型的甜胚乳性状（如皱缩种子、可溶性糖积累和淀粉变形）。定位作图表明相应基因位于7号染色体长臂上。在3.4 Mb的候选区域内，发现了一个高粱中与玉米（）编码淀粉去分支酶ISA1的直系同源基因。对SUF中的测序分析揭示了编码区存在非同义单核苷酸多态性（SNP），其中包含高度保守氨基酸的替换。用基因对水稻（）突变系进行互补恢复了甜胚乳表型。此外，对从EMS诱变突变体库中获得的突变体进行分析，发现了具有较轻微皱纹和较高糖度评分表型的新等位基因。这些结果表明是甜胚乳的相应基因。籽粒灌浆期淀粉合成基因的表达谱表明，功能丧失会影响大多数淀粉合成基因的表达，并揭示了高粱淀粉合成途径中精细调节的基因调控。利用来自高粱群体的187个不同种质进行单倍型分析，发现SUF表现出严重表型的单倍型在地方品种和现代品种中未被使用。因此，如上述EMS诱变突变体中的弱等位基因（表现为甜且皱纹较轻）对粒用高粱育种更有价值。我们的研究表明，更温和的等位基因（由基因组编辑产生）应有利于改良粒用高粱。
