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| 异子蓬二型性种子萌发差异性的生理机制 | |
| 其他题名 | The physiological mechanism for germination differentiation between dimorphic seeds of Borszczowia aralocaspica |
| 宋以刚 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 张希明 ; 李利 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 异子蓬(Borszczowia aralocaspica)是叶肉质化一年生盐生植物，在我国仅分布于准噶尔盆地南缘，是中亚荒漠植物区系特有植物种，其种子具有二型性，并表现萌发异型。其棕色种子没有休眠，形成短暂土壤种子库，能够在较宽的温度条件下萌发；黑色种子种皮光滑，具有浅生理休眠，形成持久种子库。异子蓬的萌发异型是对不利和干扰生境的适应策略。本论文通过扫描电镜、离子分析和盐分胁迫实验，研究了其萌发异型产生的生理机制，结果如下：\n(1)异子蓬在繁殖后代、产生二型性种子时，对两类种子的繁殖投入存在差异。棕色种子的可溶性糖、可溶性蛋白质和N、P养分全量，以及K+/Na+ 和Mg2+/Na+显著高于黑色种子，这是导致异子蓬二型性种子萌发差异的重要原因之一。\n(2)异子蓬二型性种子种皮结构存在差异，棕色种子具有一层薄种皮；而黑色种子具有两层种皮，外种皮光滑坚硬致密，厚度是内种皮的4-5倍，内种皮与棕色种子的种皮非常相似，有一层附属物。\n(3)异子蓬二型性种子对盐分胁迫的响应不同。盐胁迫下棕色种子迅速吸水萌发，快速生长，以脱离土壤表层的高盐环境；黑色种子通过特有的外种皮阻止外部盐分的进入以避盐，保护胚胎。\n本研究表明，异子蓬黑色种子厚实、坚硬、致密的外种皮对胚胎起着重要的保护作用，它隔离了外界高浓度的盐碱环境对胚胎的生理毒害，保持了胚胎的活性，是其作为永久土壤种子库的重要保障。而在繁殖分配过程中，母本倾向于将更多的耐盐物质分配给棕色种子，迅速萌发和较高水平的K+含量使其迅速摆脱地表高盐环境，保证了幼苗成活率。这些都是异子蓬二型性种子对荒漠环境的适应性进化。 |
| 英文摘要 | Borszczowia aralocaspica, an annual halophyte, distributes in the Zhungar Basin in China. It is an endemic species in the desert of the Central Asian. The species have dimorphic seeds and exhibit differences in germination behavior. Its brown seeds are non-dormant and germinate in a wide range of temperature, forming a transient soil seed bank. Its black seeds are in non-deep physiological dormancy (PD), and form the persistent soil seed banks. Differences in germination behavior of B. aralocaspica are an adaptive strategy to adverse and disturbed habitat. The physiological mechanism for germination differentiation between dimorphic seeds of B. aralocaspica was investigated by scanning electric microscope (SEM), ion and nutrition analysis. It was concluded:\n(1) In the process of reproduction, resource allocation of the maternal plant to dimorphic seeds is different. In brown seeds, content of soluble sugar and protein, concentration of N, P and the ratio of K+/Na+ and Mg2+/Na+ were higher than in black seeds. This may result in distinct differences in dormancy and germination mechanism. \n(2) There is a significant difference in seed coat structure of dimorphic seeds in B. aralocaspica. In black seeds, seed coat consisted of two layers: exotesta (black) and endotesta (brown), but in brown seeds only one layer. The surface of the exotesta for black seeds is plain and smooth with a layer of appendage. Brown seeds’ testa is very rough. The endotesta of black seeds is similar to the testa of brown seeds in structure. Exotesta of black seeds is about 4-5 times thicker than its endotesta.\n(3) Different responses to NaCl solution between dimorphic seeds of B. aralocaspica were observed. Under the salt stress, brown seeds are able to uptake water and germinate rapidly. Its radicles elongate rapidly to escape from high salinity in soil surface; In black seeds, its peculiar exotesta prevents salt ion from entering into embryos to avoid salinity damage. \nThis study demonstrates that the thick, hard and compact exotesta of black seeds plays an important protective roles on the embryo, which isolates the physiological poison of high concentration of saline environment on embryo, maintains the activity of the embryo, and it is the important guarantee to be a permanent soil seed bank. The female parent tends to assign more salt-tolerant material to the brown seeds in the reproductive allocation process. Rapid germination and a higher level of K+ content allow them to quickly get rid of the high-salt environment on the surface, to ensure the survival rate of seedlings. These are the adaptive evolution of dimorphic seeds for the desert environment. |
| 中文关键词 | 异子蓬 ; 种子二型性 ; 盐生植物 ; Na+ ; K+ ; SEM ; 适应策略 |
| 英文关键词 | Borszczowia aralocaspica seed dimorphic halophyte Na+ K+ SEM adaptive strategy |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 植物学 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287142 |
| 推荐引用方式 GB/T 7714 | 宋以刚. 异子蓬二型性种子萌发差异性的生理机制[D]. 中国科学院大学,2012. |
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