National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing, 100083, China.
Key Laboratory of Soil and Water Conservation and Desertification Combating, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing, 100083, China.
J Plant Physiol. 2018 Nov;230:109-121. doi: 10.1016/j.jplph.2018.10.011. Epub 2018 Oct 17.
Raffinose family oligosaccharides (RFOs) accumulate during seed development, and have been thought to be associated with the acquisition of desiccation tolerance (DT) by seeds. Here, comprehensive approaches were adopted to evaluate the changes of DT in developing Arabidopsis seeds of wild type, overexpression (OX-AtGS1/GS2/RS5), and mutant lines by manipulating the expression levels of the GALACTINOL SYNTHASE (GS) and RAFFINOSE SYNTHASE (RS) genes. Our results indicate that seeds of the double mutant (gs1, gs2) and rs5 delayed the timing of DT acquisition as compared to wild type. Subsequent detection confirmed that seeds from OX-AtGS1/GS2 plants with high levels of galactinol, raffinose, and stachyose, and OX-AtRS5 plants possess more raffinose and stachyose but less galactinol compared to wild type. These lines all showed greater germination percentage and shorter time to 50% germination after desiccation treatment at 11 and 15 days after flower (DAF). Further analysis revealed that the role of RFOs is time limited and mainly affects the middle stage (9-16 DAF) of seed development by enhancing seed viability and the ratio of GSH to GSSH in cells, but there is no significant difference in DT of mature seeds. In addition, RFOs could reduce damage to seeds caused by oxidative stress. We conclude that GALACTINOL SYNTHASE and RAFFINOSE SYNTHASE play important roles in DT acquisition during Arabidopsis seed development, and that galactinol and RFOs are crucial protective compounds in the response of seeds to desiccation stress.
棉子糖家族低聚糖（RFOs）在种子发育过程中积累，并且被认为与种子获得干燥耐受性（DT）有关。在这里，我们采用综合方法来评估通过操纵半乳糖醇合酶（GS）和棉子糖合酶（RS）基因的表达水平，改变野生型、过表达（OX-AtGS1/GS2/RS5）和突变体系中拟南芥种子的 DT 变化。我们的结果表明，与野生型相比，双突变体（gs1，gs2）和 rs5 的种子获得 DT 的时间延迟。随后的检测证实，与野生型相比，具有高水平半乳糖醇、棉子糖和水苏糖的 OX-AtGS1/GS2 植物和 OX-AtRS5 植物的种子具有更多的棉子糖和水苏糖，但半乳糖醇较少。这些品系在 11 天和 15 天后进行干燥处理后，发芽率更高，达到 50%发芽的时间更短。进一步的分析表明，RFOs 的作用是时间有限的，主要通过增强种子活力和细胞中 GSH 与 GSSH 的比例来影响种子发育的中间阶段（9-16 DAF），但对成熟种子的 DT 没有显著影响。此外，RFOs 可以减少氧化应激对种子造成的损害。我们得出结论，半乳糖醇合酶和棉子糖合酶在拟南芥种子发育过程中对 DT 的获得起着重要作用，半乳糖醇和 RFOs 是种子对干燥胁迫反应的关键保护化合物。
