Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.
Hubei Province Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables, College of Life Science and Technology, Hubei Engineering University, Xiaogan, 432000, Hubei, China.
BMC Plant Biol. 2020 Oct 6;20(1):457. doi: 10.1186/s12870-020-02666-z.
Starch in the lotus seed contains a high proportion of amylose, which endows lotus seed a promising property in the development of hypoglycemic and low-glycemic index functional food. Currently, improving starch content is one of the major goals for seed-lotus breeding. ADP-glucose pyrophosphorylase (AGPase) plays an essential role in regulating starch biosynthesis in plants, but little is known about its characterization in lotus.
We describe the nutritional compositions of lotus seed among 30 varieties with starch as a major component. Comparative transcriptome analysis showed that AGPase genes were differentially expressed in two varieties (CA and JX) with significant different starch content. Seven putative AGPase genes were identified in the lotus genome (Nelumbo nucifera Gaertn.), which could be grouped into two subfamilies. Selective pressure analysis indicated that purifying selection acted as a vital force in the evolution of AGPase genes. Expression analysis revealed that lotus AGPase genes have varying expression patterns, with NnAGPL2a and NnAGPS1a as the most predominantly expressed, especially in seed and rhizome. NnAGPL2a and NnAGPS1a were co-expressed with a number of starch and sucrose metabolism pathway related genes, and their expressions were accompanied by increased AGPase activity and starch content in lotus seed.
Seven AGPase genes were characterized in lotus, with NnAGPL2a and NnAGPS1a, as the key genes involved in starch biosynthesis in lotus seed. These results considerably extend our understanding on lotus AGPase genes and provide theoretical basis for breeding new lotus varieties with high-starch content.
莲子中的淀粉含有很高比例的直链淀粉，这使得莲子在开发降血糖和低血糖指数的功能性食品方面具有很大的潜力。目前，提高淀粉含量是莲子育种的主要目标之一。ADP-葡萄糖焦磷酸化酶（AGPase）在植物淀粉生物合成中起着至关重要的作用，但关于其在莲中的特性知之甚少。
我们描述了以淀粉为主要成分的 30 个莲子品种的营养成分。比较转录组分析表明，两种淀粉含量差异显著的品种（CA 和 JX）中 AGPase 基因表达存在差异。在莲基因组（Nelumbo nucifera Gaertn.）中鉴定出 7 个推定的 AGPase 基因，它们可以分为两个亚家族。选择压力分析表明，纯化选择是 AGPase 基因进化的重要力量。表达分析表明，莲 AGPase 基因的表达模式存在差异，其中 NnAGPL2a 和 NnAGPS1a 的表达最为显著，尤其是在种子和根茎中。NnAGPL2a 和 NnAGPS1a 与许多淀粉和蔗糖代谢途径相关基因共同表达，其表达伴随着 AGPase 活性和莲子淀粉含量的增加。
在莲中鉴定出 7 个 AGPase 基因，其中 NnAGPL2a 和 NnAGPS1a 是参与莲子淀粉生物合成的关键基因。这些结果极大地扩展了我们对莲 AGPase 基因的理解，为培育高淀粉含量的新型莲品种提供了理论基础。
