Physiological and Transcriptomic Analysis Reveals Distorted Ion Homeostasis and Responses in the Freshwater Plant Spirodela polyrhiza L. under Salt Stress
Physiological and Transcriptomic Analysis Reveals Distorted Ion Homeostasis and Responses in the Freshwater Plant Spirodela polyrhiza L. under Salt Stress
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DOI：
10.3390/genes10100743
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发表时间：
2019-10-01
期刊：
影响因子：
3.5
通讯作者：
Zhang, Jiaming
中科院分区：
文献类型：
--
作者：
Fu, Lili;Ding, Zehong;Zhang, Jiaming
浮萍是淡水被子植物的一个科，形态退化为叶状体，通过营养芽繁殖。与拟南芥、水稻等其他被子植物的光合器官与土壤之间存在物理屏障不同，浮萍的光合器官直接面向营养供应源（沃茨），因此它们对盐分的反应可能不同。本研究中，我们发现水萍螺旋藻（Spiroplopolyrhiza L.）在盐胁迫下，小麦叶片中钠含量高积累，钾、钙含量大幅度降低。100 mM和150 mM NaCl处理后，鲜重、Rubisco和AGE 2活性以及淀粉含量在第1天显著下降，但随后逐渐恢复，第3 ~ 5天积累的淀粉含量高于对照。共鉴定出2156个差异表达基因。与乙烯代谢、主要CHO降解、脂类降解、氮代谢、类黄酮次生代谢和非生物胁迫相关的基因显著增加，而与细胞周期和组织、细胞壁、ATP合成的线粒体电子传递、光合作用的光反应、生长素代谢和四吡咯合成相关的基因受到抑制。此外，盐胁迫还显著影响了主要参与非生物胁迫和细胞分化的转录因子的表达。盐胁迫下，大部分敏感钙反向转运体（OSCA）和钾内向通道表达下调，Na+/H+反向转运体（SOS 1和NHX）和Na+/Ca 2+交换体表达上调，但大多数对盐胁迫反应不明显。这些结果表明，离子稳态受到强烈干扰。最后，讨论了浮萍与其他植物在盐胁迫反应中共同的、独特的调控网络。这些研究结果为深入了解浮萍盐胁迫响应机制提供了新的思路，为浮萍耐盐性改良及其在盐胁迫条件下的应用奠定了基础。
Duckweeds are a family of freshwater angiosperms with morphology reduced to fronds and propagation by vegetative budding. Unlike other angiosperm plants such as Arabidopsis and rice that have physical barriers between their photosynthetic organs and soils, the photosynthetic organs of duckweeds face directly to their nutrient suppliers (waters), therefore, their responses to salinity may be distinct. In this research, we found that the duckweed Spirodela polyrhiza L. accumulated high content of sodium and reduced potassium and calcium contents in large amounts under salt stress. Fresh weight, Rubisco and AGPase activities, and starch content were significantly decreaseded in the first day but recovered gradually in the following days and accumulated more starch than control from Day 3 to Day 5 when treated with 100 mM and 150 mM NaCl. A total of 2156 differentially expressed genes were identified. Overall, the genes related to ethylene metabolism, major CHO degradation, lipid degradation, N-metabolism, secondary metabolism of flavonoids, and abiotic stress were significantly increased, while those involved in cell cycle and organization, cell wall, mitochondrial electron transport of ATP synthesis, light reaction of photosynthesis, auxin metabolism, and tetrapyrrole synthesis were greatly inhibited. Moreover, salt stress also significantly influenced the expression of transcription factors that are mainly involved in abiotic stress and cell differentiation. However, most of the osmosensing calcium antiporters (OSCA) and the potassium inward channels were downregulated, Na+/H+ antiporters (SOS1 and NHX) and a Na+/Ca2+ exchanger were slightly upregulated, but most of them did not respond significantly to salt stress. These results indicated that the ion homeostasis was strongly disturbed. Finally, the shared and distinct regulatory networks of salt stress responses between duckweeds and other plants were intensively discussed. Taken together, these findings provide novel insights into the underlying mechanisms of salt stress response in duckweeds, and can be served as a useful foundation for salt tolerance improvement of duckweeds for the application in salinity conditions.