几种红树植物的木材解剖学研究

【作者】 邓传远；

【导师】 林鹏；

【作者基本信息】 厦门大学 ， 植物学， 2001， 博士

【摘要】 本文研究了海桑科海桑属、使君子科榄李属、红树科木榄属、角果木属、秋茄属、红树属等15种红树植物的木材解剖特征。通过光学显微镜、扫描电子显微镜、激光共聚焦成像显微镜的观察，详细描述了研究植物次生木质部导管(管孔)、射线、纤维、轴向薄壁组织等结构的形态特征。应用Lasersharp软件测量了研究植物次生木质部导管(管孔)、射线、纤维数量特征的24项指标。根据观测结果，讨论了15种研究植物的系统学、分类学、生态学意义。同时，应用Lasersharp甲软件，测量了红海榄、海莲、海桑、秋茄等4种植物导管(管孔)数量特征在河口不同生境条件下的种内变动。利用统计分析方法，分析了种内导管数量特征的不同与土壤盐份含量和养分含量的关系。 1． 首次系统报道了中国现有海桑属所有种的木材解剖特征。结果表明： A) 海桑属植物木材结构的特化与潮间带生境是相适应的，能在水分胁迫的生境中，有效地协调水分输导的有效性和安全性。其特化结构包括：(1)宽、窄导管并存；(2)管孔密度较大，复孔率高；(3)存在纤维状导管和少量环管管胞；(4)螺旋雕纹、附物纹孔、管壁具疣等许多导管壁的微观结构有利于水分输导的安全性；(5)射线细胞和分隔木纤维内的淀粉粒是渗透调节的物质基础，有利于促进水分上升；(6)纤维壁的厚度较薄和纤维腔径较宽，这有利于水分的贮存。 B) 某些海桑属植物木材结构具有种类鉴定意义。杯萼海桑和无瓣海桑具硬化侵填体，可区别于海桑属其余4种。卵叶海桑的射线高度和射线宽度远大于其余海桑属种类，由于射线的数量特征与个体发育时间有关，这一特征可作为卵叶海桑区别于其它种类的辅助特征。 C) 木材比较解剖的结果表明海桑属可以归入千屈菜科。因为海桑属和紫薇属的木材结构中，与木质部进化的主要趋势相关的木材结构异常相似(除木薄壁组织类型不同外)。 D) 导管数量特征的聚类分析可以把海桑属聚成两类：(1)海桑和拟海桑：(2)杯萼海桑、卵叶海桑、无瓣海桑、海南海桑。这证明了海桑属导管的数量特征具系统演化意义。海桑属植物沿两支进化，一支逐渐进化为水分输导效率高的种类(具宽的导管直径和大的输导面积，小的管孔密度如海桑和拟海桑)，另一支逐渐进化为水分输导安全性高的种类(具窄的导管直径和小的输导面积，高的管孔密度如杯萼海桑、卵叶海桑、无瓣海桑、海南海桑) 2． 首次利用比较解剖学的研究结果对榄李和红榄李生态隔离现象进行了合理的解释。榄李和红榄李木材比较解剖学的研究结果表明，生境条件较为相似的情况下，红榄李具有比榄李显著更宽的导管，使它的输导率增大(估定有效输导率为榄李的3倍)，这在竞争中更容易获得生长所必须的营养物质。因而，在生境条件较为优越的时候(如盐度较低，有机营养较丰富的生境中)，红榄李容易在竞争中取得优势，而把榄李排挤掉。然而，榄李因具有更窄的管孔直径，更高的管孔密度，有利于水分输导的安全性，在盐度较高(水分胁迫)的生境中，更容易存活下来。由此推测榄李和红榄李木材结构的差异至少是这两种植物生态隔离现象的一个原因。 3． 应用激光共聚焦成像显微镜结合光学显微镜、扫描电子显微镜对研究植物次生木质 部的形态特征进行了观察，首次报道了：（）研究的15种红树植物具有纤维状导管； （2）海生红树科植物具有附物纹孔：（3）15种红树植物具有丰富的导管螺旋雕纹。 并对研究植物附物的位置、形态、多少进行了详细描述。根据这些结果，我们提出 了一些新的观点： A）榄李属植物附物纹孔的差异具种类鉴定意义。红榄李纹孔具网状附物且纹孔口 间相互连接沟具网状附物，榄李纹孔无附物，或仅具有颗粒状附物，纹孔口间 相互连接沟无附物或仅具有颗粒状附物。 B）榄李属管孔直径及附物纹孔的差异表明附物纹孔的结构有助于输导安全性。榄 李在进化过程中形成了高管孔密度和窄的管孔直径以保证输导的安全性，则在 进化中，附物逐渐消失，仅有少量附物存在。红榄李管孔直径比拨李大，容易 倒塌，容易形成栓塞，因而进化过程中，附物成为输导安全性的辅助结构。 C）海生红树植物具有附物纹孔为红树科的系统位置提供了确凿的、令人信服的证 据，即红树科隶属于桃金娘目这一系统分类是正确的。4．首次阐明了红树植物中耐寒性强的种类的木材结构基础。红树科红树植物次生木质 部比较解剖学研究表明秋茄具有如下三特点：（）管孔直径极小（管孔平均弦向直 径：48．41】m；管孔平均径向直径：39．47口m）：（2）具有发达的轴向薄壁组织（呈带状 傍管型薄壁组织）；（3）具有发达的射线薄壁组织（射线比率：40．45％）。这些构成了 秋茄耐寒性的结构基础。5．海生红树科植物木材结构具种类鉴定特征。红树科红树族由木横属、．角果木属、秋 茄属、红树属4个属组成，射线的类型及轴向薄壁组织类型可以作为属的鉴定特征， 而射线两端翼的特征，分泌细胞和硬化侵填体存在与否，可以作为种的鉴定特征。 据此原则，我们制定出如下检?更多还原

【Abstract】 STUDIES ON WOOD ANATOMY OF SOME MANGROVE SPECIESDeng Chuanyuan(School of life science. Xiamen University, Xiamen 361005)Wood anatomical features of 15 mangrove species belonging to Sonneratia, Lumnitzera, Rhizophoraceae including Bruguiera, Ceriops. Kandelia, Rhizophora were surveyed and analyzed. The morphological features of vessels (pores),fibers, rays and axial parenchyma in secondary xylem were described thoroughly by means of optical microscopy, scanning electronic microscopy and laser scanning confocal microscopy. The quantitative features of vessels (pores), fibers, rays in secondary xylem were measured by means of software Lasersharp. These results were used for the identification of species, related to systematic position and correlated with ecological adaptation to intertidal habitats. Variations in the qnantitative wood anatomical features of vessel elements (pores) of R. stylosa, S. caseolaris, B. sexangula, K. candel with different habitats along estuary were studied. Relationship between physicochemical variables in soil and quantitative wood anatomical features were analyzed by means of statistical methods.1. Wood anatomical features of all Sonneratia species native to China were surveyed systematically for the first time. The results showed:A) The specialized wood structures in Sonneratia, which can coordinate conductive capacity with conductive safety, are adaptive to intertidal habitats. These character states include: (1) wide and narrow vessel elements (pores) co-occur; (2) the high pore density and a great percentage of pores in clusters occur; (3) the vesturing and helical structure in Sonneratia improve conductive safety; (4) starch grains in ray cells and septate fibers may have the effect of facilitating conduction by providing a source for sugar transfer into vessels; (5) the wide lumen in fiber is obviously a water storage. 8) Some wood structures are indicative of diagnostic features. S. alba and S. apetala characterized by sclerosed tyloses can be distinct from the other Sonneratia species. Compa/ed to the other Sonneratia species, ray height in S. ovata is significantly higher and ray width is significantly wider. These characters can be used for subsidiary diagnostic features considering that quantitative features in ray are relative to ontogeny.C) Data from wood anatomy supports inclusion of Sonneratia in Lythraceae, which accords with recent results from phylogenetic analysis based on ITS sequences of rDNA. Wood structures relative to main trends in xylem evolution in both Sonneratia and Lagerstroemia showed great similarity except for axial parenchyma types.D) Clustering based on quantitative characters of vessel elements (pores) indicated two clades contain: (\) S. caseoalris and S. caseolaroides\ (2) S. alba, S. ovata, S. apetala and S. hainanensis, which suggests the significance of phytogeny, namely, the Sonneratia species formed into two clades in the course of evolution, one including S. caseoalris and S. caseolaroides by formation of the wider vessel and lower pore131density means high conductive efficiency, the other including S. alba, S. ovata, S. apetala and S. hainanensis by formation of the narrower vessel and higher pore density means high conductive safety.2. The results of comparative wood anatomy between L. littorea and L. racemosa can be used to explain why two species occupy different ecological sites reasonably. Under similar habitats, estimated specific conductance relative to conductive efficiency in L. littorea is 3 times more than that in L. racemosa, which suggests that L. littorea can obtain nutrition and water more readily in the suitable habitats, and thus L. littorea supplant L. racemosa by competition. However, narrower pores and higher pore density occur in L. racemosa, these character states relative to conductive safety are adaptive to saline habitats (water stress), and then can survive more easily under more saline habitats. According to the above description, the difference in wood structure更多还原