Tetradesmus obliquus is an oleaginous microalga with high potential for triacylglycerol production. We characterized the biochemical composition and the transcriptional landscape of T. obliquus wild-type and the starchless mutant (slm1), adapted to 16:8 h light dark (LD) cycles under nitrogen limitation. In comparison to the nitrogen replete conditions, the diurnal RNA samples from both strains also displayed a cyclic pattern, but with much less variation which could be related to a reduced transcription activity in at least the usually highly active processes. During nitrogen limitation, the wild-type continued to use starch as the preferred storage compound to store energy and carbon. Starch was accumulated to an average content of 0.25 g·g_DW⁻¹, which is higher than the maximum observed under nitrogen replete conditions. Small oscillations were observed, indicating that starch was being used as a diurnal energy storage compound, but to a lesser extent than under nitrogen replete conditions. For the slm1 mutant, TAG content was higher than for the wild-type (average steady state value was 0.26 g·g_DW⁻¹ for slm1 compared to 0.06 g·g_DW⁻¹ for the wild-type). Despite the higher TAG content in the slm1, the conversion efficiency of photons into biomass components for the slm1 was only half of the one obtained for the wild-type. This is related to the observed decrease in biomass productivity (from 1.29 g_DW·L⁻¹·day⁻¹ for the wild-type to 0.52 g_DW·L⁻¹·day⁻¹ for the slm1). While the transcriptome of slm1 displayed clear signs of energy generation by degrading TAG and amino-acids during the dark period, no significant variation of these metabolites could be measured. When looking through the diurnal cycle, the photosynthetic efficiency was lower for the slm1 mutant compared to the wild-type especially during the second half of the light period, where starch accumulation occurred in the wild-type.

斜生Tetradesmus是一种油性微藻，具有高生产三酰基甘油的潜力。我们表征了T. obliquus野生型和无淀粉突变体（slm1）的生化组成和转录景观，适应了氮限制下的16：8 h暗（LD）循环。与氮充足的条件相比，来自两个菌株的昼夜RNA样品也显示出环状模式，但变化较小，这可能与至少在通常高度活跃的过程中转录活性降低有关。在氮限制期间，野生型继续使用淀粉作为优选的存储化合物来存储能量和碳。淀粉的平均含量为0.25 g·g _DW ^-1，高于在充氮条件下观察到的最大值。观察到小的振荡，表明淀粉被用作昼夜能量存储化合物，但是程度小于在氮充足条件下。对于slm1突变体，TAG含量高于野生型（slm1的平均稳态值为0.26 g·g _DW ^-1，而野生型为0.06 g·g _DW ^-1）。尽管在较高的TAG含量SLM 1，光子的转换效率为生物质组分的SLM 1仅为野生型获得的一半。这与在生物质生产力所观察到的下降（从1.29克_DW ·L ^-1 ·天^-1的野生型到0.52克_DW ·L ^-1 ·天^-1的SLM 1）。虽然slm1的转录组在黑暗时期通过降解TAG和氨基酸显示出明显的能量产生迹象，但这些代谢物没有明显变化。观察昼夜周期时，slm1的光合效率较低 突变体与野生型相比，尤其是在光照期的后半期，其中淀粉积累发生在野生型中。