Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原针茅属植物生态适应性及其分子机制的研究 | |
| 其他题名 | Studies on ecological adaptation and molecular mechanism of Stipa species on Tibetan Plateau |
| 杨时海 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 杨永平 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 羌塘高原位于青藏高原腹地，平均海拔在4000m以上，气候寒冷干旱，具有面积广阔的高寒草原植被。该地区由于受到西南季风及西风环流气候的影响，降水自东南向西北呈现逐渐减少的趋势，水分成为该地区植被发育的主要限制因素之一。羌塘高原自东至西依次分布着以丝颖针茅为主的高寒草原化草甸、以紫花针茅为主的高寒草原及以沙生针茅为主的高寒荒漠化草原。迄今，对该地区针茅属植物生态适应性机制不甚清楚，本文基于种子生态学、形态解剖结构、生理生化、蛋白组学、转录组学及功能基因方面的研究，以期揭示针茅属植物生态适应的分子机制。论文研究的主要结论如下： 1. 水分对种子萌发的影响。光照条件下，沙生针茅在干旱条件下（-0.6MPa）萌发率升高，紫花针茅和丝颖针茅萌发率在各水势梯度都高于沙生针茅；在黑暗条件下，紫花针茅与丝颖针茅萌发率高于沙生针茅；恒温下，紫花针茅与沙生针茅在20℃时萌发率最高，而丝颖针茅在15 ℃时萌发率最高；变温刺激种子萌发率。光照抑制针茅属植物种子萌发。沙生针茅、紫花针茅及丝颖针茅的基础温度为-1.0 ℃ ，0.1 ℃ ，-1.4 ℃，低于温带地区植物的基础温度0-4℃之间；基础温度低，需要积累积温时间长。丝颖针茅处于降水较多的地区，温度较低；随着埋深的增加，种子萌发率逐渐减小。紫花针茅的萌发率最高。种子生态学研究表明，湿润生境物种的萌发高于干旱生境物种，干旱胁迫能够提高干旱生境物种种子萌发率。种子来源很大程度上决定种子萌发率。紫花针茅种子萌发率最高，为维持高寒草原生态系统和幼苗更新起着重要作用。 2. 针茅属植物对干旱胁迫生理生化响应。在干旱胁迫条件下，沙生针茅和紫花针茅生理指标（叶绿素荧光参数、叶片相对含水量、土壤相对含水量及存活率）都明显高于丝颖针茅。同时，在受到干旱胁迫过程中，沙生针茅和紫花针茅抗氧化酶APX和CAT含量，MDA含量高于丝颖针茅。证明沙生针茅和紫花针茅抗旱性强于丝颖针茅。 3. 针茅属植物对干旱胁迫的生态适应性。针茅属植物随着降水梯度的减少，叶片厚度、最大叶片厚度及最小叶片厚度发生明显变化。沙生针茅叶片厚度、最大叶片厚度及最小叶片厚度均大于紫花针茅和丝颖针茅。在自然状态条件下，紫花针茅从开始在叶片表皮积累角质层，而沙生针茅和丝颖针茅在受到干旱胁迫诱导后，逐渐开始在叶片表皮积累角质层。沙生针茅在复水后角质层积累达最大值，而丝颖针茅在复水后角质层积累下降。结果证明沙生针茅和紫花针茅抗旱性强于丝颖针茅。干旱能够促使针茅属植物叶片表皮角质层的累积，是针茅属植物对干旱胁迫响应的主要表达方式。 在自然状态下，沙生针茅和紫花针茅的卷曲度要低于丝颖针茅。在干旱胁迫后，沙生针茅和紫花针茅卷曲程度要强于丝颖针茅。而卷曲程度的调控受到泡状细胞的调控。泡状细胞失水诱导针茅属植物叶片相互折叠。同时，沙生针茅和紫花针茅气孔闭合程度强于湿润地区的丝颖针茅，气孔优先于其它调节方式闭合，从而减少二氧化碳和水蒸汽通量。 4. 针茅属植物在蛋白组水平差异表现在脂类合成相关蛋白、干旱胁迫响应蛋白和水分运输相关蛋白。结果发现脂类相关蛋白GDSL脂酶/脂肪酶调控角质层的合成。沙生针茅和紫花针茅在干旱胁迫条件下，GDSL脂酶/脂肪酶LIP4下调表达，促进角质层合成，而丝颖针茅无表达，从而在形态结构上反映物种响应干旱的差异性；沙生针茅和紫花针茅干旱相关的蛋白（抗氧化酶蛋白和热休克蛋白）表达量显著于丝颖针茅。紫花针茅在干旱胁迫条件下水分运输蛋白表达量强于沙生针茅和丝颖针茅。 5. 利用转录组测序技术获得沙生针茅79888条unigene，平均长度为765.58 bp，N50为1289；紫花针茅78489条unigene，平均长度为788.94，N50为1329；丝颖针茅75671条unigene，平均长度为791，N50为1151。表明转录组测序数据质量可靠，可信度高。沙生针茅干旱胁迫后，与脂类相关基因表达数量多，复水后下调表达，显著于紫花针茅和丝颖针茅，表明沙生针茅抗旱性强于紫花针茅和丝颖针茅。 6. 克隆获得三种针茅属植物质膜内在蛋白。SpPIP1基因开放阅读框长为870bp，编码289个氨基酸，GenBank号为KM276547；SgPIP1基因开放阅读框长为867bp，编码288个氨基酸，GenBank号为KM276549；ScPIP1基因开放阅读框长为867bp，编码288个氨基酸，GenBank号为KM276548。它们共有特征为含有2个高度保守的NPA模体。过表达SpPIP1转基因拟南芥能够提高植株的耐盐性。 |
| 英文摘要 | The Qiangtang Plateau is located in the hinterland of the Tibetan Plateau. It is characterized by high altitude, cold and arid climate, and widespread alpine steppe. The climate in this region was influenced by southwestern monsoon which resulted in gradually decreasing trend of precipitation from southeastern to northwestern region along the longitude change. Precipitation is one of key environmental factor for vegetation formation. Thus, vegetation type was partitioned to alpine steppe-meadow, alpine steppe, and alpine deserted steppe dominated by Stipa capillacea, S. purpurea, and S. glareosa, respectively. So far, there were few reports upon ecological adaptation of Stipa species. In this study, we studied seed ecology, anatomical structure, physiological and biochemical assays, proteomics, transcriptomics, and functional genomics to reveal molecular mechanisms of ecological adaptation in Stipa species. The major conclusions are as follows: 1. Water potential had significant effect on seed germination. Under light, S. glareosa at -0.6 MPa had the highest germination percentage among all water potential, while germination percentage of S. purpurea and S. capillacea under each water potential was higher than S. glareosa. Germination percentage of S. purpurea and S. capillacea was higher than S. glareosa under complete dark. Under constant temperature, the maximum value of germination percentage was 70% at 15℃ in S. capillacea, 61% at 20℃ in S. glareosa, and the maximum value was 87% at 20℃ in S. purpurea. Alternating temperature could stimulate seed germination. The highest base temperature, 0.1℃, was recorded for S. purpurea, while the base temperature of S. glareosa was found to be -1.0℃, the lowest base temperature , -1.4 was found for S. capillacea, which were higher than temperate region. Low basal temperature allows seeds to accumulate heat when temperature was low. Germination percentage of Stipa species was reduced with increase of burial depth. S. purpurea had the highest germination percentage among three Stipa species. It was suggested that germination percentage of moist habitat species was higher than dry land region. Drought stress could increase germination percentage of dry land species. Provenance of seed determined to some extent seed germination. High germination percentage of S. purpurea could contribute to maintain alpine steppe ecosystem and seedling recruitment. 2. Drought stress resulted in changes of physiological and biochemical characterization. The value of Fv/Fm, leaf relative water content, soil relative water content, and survival rate was higher in S. glareosa and S. purepurea than S. capillacea. When Stipa species were subjected to drought stress, they would generate antioxidant enzymes such as APX and CAT to scavenge in vivo active oxygen species. MDA represented injury of cellular plasma membrane, which showed the content of S. capillacea was higher than S. glareosa and S. purpurea. 3. Leaf thickness, maximal leaf thickness and minimal leaf thickness among Stipa species declined with gradual decrease of precipitation along the longitude change. It was showed that the resistance to drought of S. glareosa was stronger than S. purpurea and S. capillacea. S. purpurea started to accumulate cuticle under natural growth, while S. glareosa and S. capillacea accumulate leaf cuticle after drought stress and reached the maximal value of leaf cuticle. The leaf curling angle of S. capillacea was higher than S. glareosa and S. purpurea under natural growth and after drought stress. The degree of leaf curling was regulated by leaf bulliform size after water loss which induced leaf mutual folding. Drought stress facilitated accumulation of leaf cuticle which was controlled molecularly by GDSL esterase/lipase protein. Meanwhile, leaf stomotal closure was preferential to other regulation after drought stress in order to decrease flux of carbon dioxide and water vapor. These revealed that the ecological ad |
| 中文关键词 | 青藏高原 ; 针茅属植物 ; 生态适应性 ; 分子机制 |
| 英文关键词 | Tibetan Plateau Stipa species ecological adaptation molecular mechanism |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院青藏高原研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287565 |
| 推荐引用方式 GB/T 7714 | 杨时海. 青藏高原针茅属植物生态适应性及其分子机制的研究[D]. 中国科学院大学,2015. |
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