College of Landscape Architecture and Forestry, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao 266109, China.
Academy of Dongying Efficient Agricultural Technology and Industry on Saline and Alkaline Land in Collaboration with Qingdao Agricultural University, Dongying 257000, China.
Int J Mol Sci. 2023 Feb 2;24(3):2934. doi: 10.3390/ijms24032934.
Large-scale use of fossil fuels has brought about increasingly serious problems of environmental pollution, development and utilization of renewable energy is one of the effective solutions. Duckweed has the advantages of fast growth, high starch content and no occupation of arable land, so it is a promising starchy energy plant. A new submerged duckweed mutant () with abundant starch accumulation was obtained, whose content of amylopectin accounts for 84.04% of the starch granules. Compared with the wild type (), the branching degree of starch in mutant was significantly increased by 19.6%. Chain length DP 6-12, DP 25-36 and DP > 36 of amylopectin significantly decreased, while chain length DP 13-24 significantly increased. Average chain length of wild-type and mutant starches were greater than DP 22. Moreover, the crystal structure and physical properties of starch have changed markedly in mutant. For example, the starch crystallinity of mutant was only 8.94%, while that of wild-type was 22.3%. Compared with wild type, water solubility of starch was significantly reduced by 29.42%, whereas swelling power significantly increased by 97.07% in mutant. In order to further analyze the molecular mechanism of efficient accumulation of amylopectin in mutant, metabolome and transcriptome were performed. The results showed that glucose accumulated in mutant, then degradation of starch to glucose mainly depends on α-amylase. At night, the down-regulated β-amylase gene resulted in the inhibition of starch degradation. The starch and sucrose metabolism pathways were significantly enriched. Up-regulated expression of , , , , and provide sufficient substrate for starch synthesis in mutant. From the 0H to 16H light treatment, granule-bound starch synthase () gene was inhibited, on the contrary, the starch branching enzyme () gene was induced. Differential expression of and may be an important reason for the decrease ratio of amylose/amylopectin in mutant. Taken together, our results indicated that the mutant can accumulate the amylopectin efficiently, potentially through altering the differential expression of , and . This study also provides theoretical guidance for creating crop germplasm with high amylopectin by means of synthetic biology in the future.
大规模使用化石燃料带来了日益严重的环境污染问题，开发和利用可再生能源是有效解决方案之一。浮萍具有生长迅速、淀粉含量高、不占用耕地等优点，是一种很有前途的淀粉能源植物。本研究获得了一种新型沉水浮萍淀粉积累突变体（），其淀粉颗粒中支链淀粉含量高达 84.04%。与野生型（）相比，突变体中淀粉的分支程度显著增加了 19.6%。支链淀粉 DP6-12、DP25-36 和 DP>36 的链长显著降低，而 DP13-24 的链长显著增加。野生型和突变体淀粉的平均链长均大于 DP22。此外，突变体中淀粉的晶体结构和物理性质发生了明显变化。例如，突变体的淀粉结晶度仅为 8.94%，而野生型的为 22.3%。与野生型相比，突变体淀粉的水溶性显著降低了 29.42%，而膨胀力显著增加了 97.07%。为了进一步分析突变体中支链淀粉高效积累的分子机制，进行了代谢组学和转录组学分析。结果表明，突变体中葡萄糖积累，然后淀粉降解为葡萄糖主要依赖于α-淀粉酶。在夜间，下调的β-淀粉酶基因导致淀粉降解受到抑制。淀粉和蔗糖代谢途径显著富集。上调表达的、、、、和提供了充足的底物用于突变体中淀粉的合成。从 0H 到 16H 的光照处理，颗粒结合淀粉合成酶（）基因受到抑制，相反，淀粉分支酶（）基因被诱导。和的差异表达可能是突变体中直链淀粉/支链淀粉比值降低的重要原因。综上所述，本研究表明突变体可以有效地积累支链淀粉，可能是通过改变、和的差异表达。该研究为未来通过合成生物学手段创造高支链淀粉作物种质提供了理论指导。
