Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, T1J 4B1, Canada.
Plant Cell Rep. 2020 Jul;39(7):953-969. doi: 10.1007/s00299-020-02541-z. Epub 2020 Apr 20.
Seed-specific down-regulation of AtCESA1 and AtCESA9, which encode cellulose synthase subunits, differentially affects seed storage compound accumulation in Arabidopsis. High amounts of cellulose can negatively affect crop seed quality, and, therefore, diverting carbon partitioning from cellulose to oil, protein and/or starch via molecular breeding may improve seed quality. To determine the effect of seed cellulose content reduction on levels of storage compounds, Arabidopsis thaliana CELLULOSE SYNTHASE1 (AtCESA1) and AtCESA9 genes, which both encode cellulose synthase subunits, were individually down-regulated using seed-specific intron-spliced hairpin RNA (hpRNAi) constructs. The selected seed-specific AtCESA1 and AtCESA9 Arabidopsis RNAi lines displayed reduced cellulose contents in seeds, and exhibited no obvious visual phenotypic growth defects with the exception of a minor effect on early root development in AtCESA1 RNAi seedlings and early hypocotyl elongation in the dark in both types of RNAi line. The seed-specific down-regulation of AtCESA9 resulted in a reduction in seed weight compared to empty vector controls, which was not observed in AtCESA1 RNAi lines. In terms of effects on carbon partitioning, AtCESA1 and AtCESA9 RNAi lines exhibited distinct effects. The down-regulation of AtCESA1 led to a ~ 3% relative increase in seed protein content (P = 0.04) and a ~ 3% relative decrease in oil content (P = 0.02), but caused no alteration in soluble glucose levels. On the contrary, AtCESA9 RNAi lines did not display a significant reduction in seed oil, protein or soluble glucose content. Taken together, our results indicate that the seed-specific down-regulation of AtCESA1 causes alterations in seed storage compound accumulation, while the effect of AtCESA9 on carbon partitioning is absent or minor in Arabidopsis.
纤维素合酶亚基编码基因 AtCESA1 和 AtCESA9 的种子特异性下调，差异影响拟南芥种子储存化合物的积累。高纤维素含量可能会对作物种子质量产生负面影响，因此，通过分子育种将碳分配从纤维素转向油、蛋白质和/或淀粉，可能会改善种子质量。为了确定种子纤维素含量降低对储存化合物水平的影响，使用种子特异性内含子拼接发夹 RNA（hpRNAi）构建体分别下调了拟南芥 CELLULOSE SYNTHASE1（AtCESA1）和 AtCESA9 基因，这两个基因都编码纤维素合酶亚基。所选的种子特异性 AtCESA1 和 AtCESA9 拟南芥 RNAi 系在种子中表现出纤维素含量降低，并且除了 AtCESA1 RNAi 幼苗早期根发育和两种类型的 RNAi 系中黑暗下早期下胚轴伸长的轻微影响外，没有明显的肉眼可见的生长缺陷。AtCESA9 的种子特异性下调导致种子重量与空载体对照相比降低，而在 AtCESA1 RNAi 系中未观察到这种情况。就碳分配的影响而言，AtCESA1 和 AtCESA9 RNAi 系表现出不同的影响。AtCESA1 的下调导致种子蛋白质含量相对增加约 3%（P = 0.04），油含量相对减少约 3%（P = 0.02），但可溶性葡萄糖水平没有改变。相反，AtCESA9 RNAi 系中种子油、蛋白质或可溶性葡萄糖含量没有显著降低。总之，我们的结果表明，AtCESA1 的种子特异性下调导致种子储存化合物积累发生改变，而 AtCESA9 对碳分配的影响在拟南芥中不存在或较小。
