中国特有属中国蕨属(Sinopteris)的系统位置和保护生物学研究
王卫清
学位类型硕士
导师成晓
2010-05
学位授予单位中国科学院研究生院
学位专业植物学
摘要中国蕨属(Sinopteris)为中国特有属,该属现知有两个种中国蕨(S. grevilleoides)和小叶中国蕨(S. albofusca)。本文在资源分布及濒危现状、生态适应性调查的基础上,从孢子体形态学、配子体发育、细胞学、分子系统学和生物地理学等方面对中国蕨属的系统位置和濒危机制进行了探讨。主要研究结果如下:1. 资源调查,中国蕨仅在我国云南省的大姚县、宾川县、巧家县和四川省的青川县,海拔1100-1800m的少数区域有零星分布,野外稀见。小叶中国蕨在我国北部的河北、北京和西南部的云南、四川、广西、湖南,贵州等地区都有分布,分布区海拔范围为1700-2800m。目前这2种植物的野生资源量均在日益减少,一些记载有分布的地区已经很难找到。2. 孢子体基本形态学特征,该属植物为常绿旱生小型植物。叶片革质,五角形,近三等裂。叶面光滑,背面分泌白色蜡质粉末;叶脉羽状分叉,背面明显凸起。孢子囊群着生于小脉顶端,为1-2个孢子囊组成的单孢子囊群(monangial sori),孢子囊大,圆球形,几乎无柄,环带宽。囊群盖膜质,边缘有粗大锯齿或呈圆波状。该属两种叶表皮形态基本一致:表皮细胞为不规则的狭长形,垂周壁波状;气孔器分布于叶片的下表皮,椭圆形,按Dilcher[26]的定义,气孔器类型为极细胞型和腋下细胞型。叶柄基部鳞片棕色,披针形。3. 配子体发育,采用改良Knop’s固体培养基及不同成分的土壤基质分别培养中国蕨和小叶中国蕨孢子,观察其配子体发育过程并探讨了4种不同培养基质对中国蕨配子体形态发育和有性繁殖的影响。结果表明:(1)中国蕨属植物成熟孢子黑褐色,孢子同型,正四面体,具三裂缝,极面观钝三角形,赤道面观椭圆形;孢子萌发类型为书带蕨型,原叶体发育为铁线蕨型;成熟原叶体呈对称心形;精子器突出于原叶体表面,近圆球形,成熟时盖细胞孔裂;颈卵器位于心形原叶体腹面凹陷生长点之下中脉范围内,呈离心式发育,即远离生长点的颈卵器先成熟,成熟颈卵器细长,颈部由4列细胞组成,每列3~5个细胞厚,顶端的4个盖细胞彼此分离,露出颈沟。(2)不同基质上中国蕨配子体和幼孢子体生长发育存在差异,尤其是心形原叶体的形态差别明显;腐叶土基质上的成熟原叶体上未见颈卵器的发生,因而其有性繁殖过程不能完成;原生境土和腐叶土1:1混合土基质最适合中国蕨配子体生长发育及有性繁殖;改良knop's琼脂培养基上要保证幼孢子体正常生长需追加培养液。(3)配子体生长发育过程中易受污染。无菌水湿润滤纸培养基和琼脂培养基上多为细菌、真菌等菌类污染和藻类污染,土壤基质主要是藻类、藓类及其它高等植物污染。 4. 细胞学观察, 首次对中国蕨和小叶中国蕨的染色体数目进行了观察,实验结果表明,中国蕨属这2个种的染色体数目均为2n=60,基数为x=30。5. 分子系统学, 基于rps4及rps4-trnS、atpB、atpB-rbcL和trnL-F组合序列进行最大简约性分析和Bayesian分析,结果表明:小叶中国蕨S. albofusca和中国蕨S. grevilleoides始终聚为一支,同时它们和粉背蕨属Aleuritopteris五角叶系Ser. Argentea的假银粉背蕨A. subargentea形成一个支持率极高的分支。说明中国蕨属虽然是一个自然类群,但它与粉背蕨属五角叶系的关系非常近缘。从分支图还可以看出,碎米蕨属与粉背蕨属五角叶系聚在一起,薄鳞蕨属与粉背蕨属粉背叶系Ser. Farinosae聚为一支,但均聚在不同的小分支,说明碎米蕨属和薄鳞蕨属不是单系类群。6. 种群生态及群落特征, 该属植物为小型旱生植物,主要生长于裸露石灰岩上或矮灌丛岩缝,种群内个体数量较少,在群落中处于被支配地位,竞争力较弱,分布点为阳坡,坡度较大,对海拔、湿度、光照要求严格。中国蕨所在群落常为稀树灌木草丛,小叶中国蕨常丛状分布于灌木丛中和以华山松为优势种的针叶林下。7. 土壤性质, 中国蕨原产地土壤为紫色土,土层薄,蓄水性差;小叶中国蕨原产地土壤为红壤,土壤养分不高,质地粘重,保水、保肥力强,耕性较差。二者兼为微偏酸性的高钙土,全磷、全钾、速效磷含量都比较低,有效硼含量比较高。8. 濒危原因及保护措施, 可能存在的濒危原因:(1)分布区太过狭窄,应对环境变化的能力低;(2)自身特殊的生理生态学特性:孢子萌发对湿度、光照、海拔要求苛刻,孢子繁殖不发达;生于岩石缝隙中,短的根状茎没有太多空间延伸,营养繁殖受限;(3)人类活动及自然灾害导致的原生林破坏、适宜生境丧失及生境破碎化更加速了该属植物的濒危。保护措施:(1)进一步加强野外资源的调查,明确其资源总量、分布现状和生长动态;(2)根据具体情况,以就地保护和迁地保护相结合开展保护工作;(3)尝试将分株繁殖和人工孢子繁殖技术应用于中国蕨属植物的繁殖;(4)将该属植物作为绿化观赏种开发利用。
资助项目Sinopteris, a rare genus endemic to China, has two species S. grevilleoides and S. albofusca. To explore systematic position and endangerment mechanisms of Sinopteris, its sporophyte morphological characteristics, gametophyte development, cytology, molecular phologenetics, and biogeography were investigated based on the extensive investigation of its distribution, existing circumstances and ecological adaptation. The main progresses are briefly summarized as follows:1. Resource investigation, S. grevilleoides has a scattered distribution only in very few areas of Dayao, Binchuan, Qiaojia in Yunnan and Qingchuan in Sichuan; the elevation scope of its habitate is 1100-1800m. S. albofusca distributes in areas, 1700-2800 meters above sealevel in Hebei, Beijing, Yunnan, Sichuan, Guangxi, Hunan and Guizhou. Our investigation showed that the resources of the two species were decreasing and it was very difficult to find them in wild, even in distribution areas on record. 2. Sporophyte morphological characteristics, The plants of Sinopteris are evergreen small xerophytes. Fronds are texture coriaceous, pentagon, upper surface smooth, under surface whitish-farinose; veins pinnate branching, not seen above, but very prominently raised beneath. Sori are marginal, terminal, consisting of one or two large, globose, subsessile sporangium, provided with a very broad annulus. Indusia deeply cut into triangular, toothed lobes. The form of frond epidermis of S. grevilleoides and S. albofusca bring into correspondence with each other: the epidermis cells are irregular narrow strip with sinuous anticlinal walls; the stomatal apparatus exists on the lower epidermis and its types according to Dilcher’s [26] nomination are polycytic and axillocytic. Scales attaching to the base of petiole are brown, lanceolate.3. Gametophyte development, The spores of S. grevilleoides and S. albofusca were cultured in improved Knop’s agar medium and three kinds of soil substrata respectively. Spore germination and gametophyte development were observed. The impact of four culture substrata on the gametophyte development and sexual reproduction of S. grevilleoides was compared. The results are as follows:(1) The mature spores of Sinopteris were black-brown, isospory, regular tetrahedron, trilete, blunt triangle in polar view, scoop in equatorial view. Spore germination was of Vittaria-type and gametophyte exhibited Adiantum-type development. The adult prothalli were symmetric cordate. Antheridium protruding from the surface of prothalus was nearly spherosome. Archegonium was born near the notch on the ventral face of the cordate prothalus and those near the notch matured late. Mature archegonium was tall and slender, whose neck was composed of four lines cells and three to five layerscells each line. The four cells at the top separated when the archegonium matured. (2) The gametophyte and infant sporophyte morphological development of S. grevilleoides represented very different features on different culture substrata. Mature cordate prothalli on humus soil did not bear archegonias, and thus the process of sexual reproduction ofS. grevilleoides could not be finished. The substratum composed of humus soil and original soil in ratio of 1:1 was the most suitable substratum for gametophyte development and sexual reproduction of this species. Infant sporophytes needed extra nutrient solution to sustain its growth on improved Knop's agar medium.(3) The main contaminants were bacteria, fungi and algae during sterile cultures and algae, moss and other higher plants during soil cultures.4. Cytology, Chromosome numbers of S. grevilleoides and S. albofusca were investigated firstly. The result showed that the chromosome numbers of the two species both were 2n=60 and the basic choromosome number was x=30. 5. Molecular phologenetics, The phylogeny of 26 species was estimated from combined analyses of four cpDNA sequence data sets (rps4, rps4-trnS, atpB, atpB-rbcL and trnL-F). Most parsimonious (MP) and Bayesian analysis both shows the genus Sinopteris is monophyletic with strong support and it is nearly related to A. subargentea from Ser. Argentea of Aleuritopteris. The MPsystematic tree also shows: both Leptolepidium and Cheilosoria are not monophyletic; Cheilosoria is nearly related to Ser. Argentea of Aleuritopteris and Leptolepidium is nearly related to Ser. Farinosae of Aleuritopteris.6. Population and community structure, The two species of Sinopteris mainly grow in the crevices of cliffs and the numbers of individuals within populations are small. In the community, they are less competitive and under dog. Its geographical distribution requires strict elevation, humidity and illumination. S. grevilleoides often grows in the brushwood or grass. Thickets of S. albofusca usually grows in the brushwood or coniferous forest. 7. Soil property,S. grevilleoides grows in purplish soil in wild; the soil is very thin and it isdifficult to store water. S. albofusca grows in sticky and infertile red soil. Analysis of the soil chemical property shows: the two original soils both are acid soil with high calcium and available B; their total Pand K is low.8. Endangerment factors and conservation measures, Endangerment factors: (1) Their distribution areas are so narrow that they are difficult to cope with environmental changes. (2)Their own physiological and ecological characteristics: spore germination was exigent over humidity, illumination and soil; their ecological circumstances cause their rhizomes to have no too much room to extend. Based on the previous two, reproduction by spores and rhizomes for the genus Sinopteris is limited. (3)To some extent, human-induced habitat loss, accompanying habit fragmentation, and natural disaster such as drought and fire accelerated the endangerment process. Conservation measures: (1) Have a clear and definite acquaintance to recent population size, distribution and growth dynamics by strengthening field investigation. (2) According to the specific circumstances, introduce in-situ and ex-situ conservation. (3)Rejuvenate and expand Sinopteris by adopting division propagation and artificial reproduction by spores. (4) Exploit species of the genus as greening and floral materials.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16054
专题昆明植物所硕博研究生毕业学位论文
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王卫清. 中国特有属中国蕨属(Sinopteris)的系统位置和保护生物学研究[D]. 中国科学院研究生院,2010.
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