寡营养与烯效唑协同处理促进少根紫萍淀粉快速积累的机制研究

Landoltia punctata is generally recognized as a potential aquatic plant for high content and rapid accumulation of starch. However, there is little research about molecular mechanism of its starch metablism. In previous works, we have obtained Landoltia punctata strains with high starch contents by systematic screening, and their characteristics of starch accumulation under different treatment and regulation conditions were studied. When the strains were treated with nutrient starvation or uniconazole, the starch contents could reach 45 % and 48 % from 3%, respectively, in10 days. The changes of starch metabolism pathway under these conditions have been elucidated respectively using a variety of techniques included omics. Recently, we found the starch accumulation could be improved much more (reached 72% in 10 days) when the ducweed strains were cooperatively treated with nutrient starvation and uniconazole simultaneously. So in this application, we intend to study the strains cooperatively treated with uniconazole + nutrient starvation at different levels (including carbon storage biomass and starch accumulation, analysis of enzymes involved in starch biosynthesis and degradation, transcriptome and the proteome of starch metabolic pathway and carbon fixation pathway), then the results obtained through this project will be comparatively analyzed with those previously obtained by nutrient starvation and uniconazole treatment. These works would be beneficial for us to reveal the common mechanism of their starch metabolism and to discover some common Transcription factors. The results will be very important for developing Landoltia punctata as a high-starch bio-material for wide usage such as bio-ethanol production, and will also provide us some useful clues for manipulating other plants to produce starch higher and more quickly.

少根紫萍淀粉积累快含量高，已成为关注热点，但其淀粉积累机制尚不清楚。我们在筛选获得的少根紫萍的株系上发现其分别在寡营养和烯效唑处理下10天内，淀粉含量从3%分别达到45%和48%，并采用组学等多种技术初步解析了淀粉代谢通路的变化。进而又发现寡营+烯效唑协同处理能够更大幅度地提高少根紫萍的淀粉积累能力, 10天内其淀粉含量达到72%以上，淀粉产量比对照提高了50倍以上，因此是研究淀粉快速高效积累的理想材料。本项目针对寡营养+烯效唑协同处理下少根紫萍淀粉快速大量积累的现象，从碳固定、生物量、淀粉含量和产量、淀粉代谢与碳固定的关键酶系、淀粉代谢途径及碳固定通路的转录组以及蛋白质组等方面系统研究，结合已完成的全基因组数据与前期的寡营养和烯效唑处理的结果进行比较分析，深度揭示少根紫萍淀粉快速大量积累的机制，为开发高淀粉浮萍生物材料提供理论依据，也为其它植物实现快速大量淀粉积累提供有益参考。

少根紫萍淀粉积累快含量高，已成为关注热点，但其淀粉积累机制尚不清楚。我们在筛选获得的少根紫萍的株系上发现其分别在寡营养和补充CO2处理下10天内，淀粉含量从3%分别达到45%和40%，并采用组学等多种技术初步解析了淀粉代谢通路的变化。本项目针对寡营养+CO2协同处理下少根紫萍淀粉快速大量积累的现象，从碳固定、生物量、淀粉含量和产量、淀粉代谢与碳固定的关键酶系、淀粉代谢途径及碳固定通路的转录组以及蛋白质组等方面系统研究，结合已完成的全基因组数据与前寡营养和CO2处理的结果进行比较分析，深度揭示少根紫萍淀粉快速大量积累的机制，为开发高淀粉浮萍生物材料提供理论依据，也为其它植物实现快速大量淀粉积累提供有益参考。研究结果显示，寡营养与CO2协同处理能够大幅度地提高少根紫萍的淀粉积累能力,浮萍的淀粉含量和生产速率在10天内可分别达到干重的72.2%和10.4g/m2/d，相当于38.0t/ha/y淀粉产量。通过对协同处理条件下的转录组、蛋白组测序以及酶活测定的多维度分析，揭示了该处理条件下浮萍淀粉生物合成关键基因的转录水平均显著上调，蛋白表达水平也相应提高，故酶活性也随之增加，三者相互映证。同时，淀粉生物合成途径中关键基因AGPase、GBSS和SSS的表达上调是各条件下下浮萍淀粉含量显著增加的主要原因，阐明了少根紫萍淀粉快速大量积累的一般共性机制。另一方面，在协同处理条件下，蔗糖的生物合成和运输以及木质纤维素的生物合成都减少了，而氮的再分配也增强了，所有这些变化导致木质纤维素和蛋白质含量的减少，并最终导致叶绿体中淀粉的大量积累。由此可见，浮萍是一种高效环保的淀粉生产者，而该技术（处理）易于人工操作，易于实现农业产业化，因此浮萍可以作为淀粉代谢研究的理想生物反应器和模型，也是极具应用潜力的下一代淀粉类作物。