Root system architecture and gravity perception of a mangrove plant,Sonneratia alba J. Smith

We describe the features of the root system and the gravitropism of roots produced bySonneratia alba. The root system consists of four root types with different growth directions: (a) Pneumatophores, which are negatively orthogravitropic and their statocytes are very large (922 μm²) and the statolith is located near the proximal wall, (b) Cable roots and (c) Feeding roots which are both diagravitropic and their statoliths are settled along the longitudinal wall, and (d) Anchor roots which are positively orthogravitropic. The statocyte cells are the smallest (420 μm²) and statoliths settled at the distal wall. We found that all roots with marked gravitropism have statoliths that settle along different walls of the statocyte. This implies that the statoliths sensing of gravity is done by gravity on mass, and that they are denser than surrounding cytoplasm and this position is related to root growth direction. This finding matches the statoliths sediment under the effect of gravity. Irrespective of statolith, position and direction of growth may be stable.     

无瓣海桑与乡土红树植物混交对林地大型底栖动物的影响

选择广东省雷州市附城镇和珠海市淇澳岛沿海1年生无瓣海桑人工林,分别在林下混种乡土红树植物红海榄或木榄幼苗,对混交林和无瓣海桑纯林林地大型底栖动物群落进行比较,探讨无瓣海桑与乡土红树植物混交对林地大型底栖动物的影响。结果显示,混交林和无瓣海桑纯林之间大型底栖动物群落的优势种存在差异;相似性分析检验(One-Way ANOSIM)、等级聚类和非参数多变量标序结果均表明1年无瓣海桑+红海榄混交林、1年无瓣海桑+木榄混交林和1年无瓣海桑纯林之间大型底栖动物群落结构差异显著。研究还发现在无瓣海桑人工林林下混交红海榄或木榄这两种乡土红树植物,可提高林地底栖动物的生物量和物种多样性。BIOENV分析说明大型底栖动物分布与红海榄或木榄这两种混交的乡土树种的凋落物量密切相关,这进一步证实了混交乡土红树植物对林地底栖动物多样性和分布的影响。两个研究地实验结果均显示,在无瓣海桑林下种植木榄的效果要优于红海榄,表现在木榄的平均苗高、凋落物量、凋落物量占群落凋落物总量百分比和幼苗成活率均高于红海榄,其对提高林地大型底栖动物生物量和物种多样性的效果也明显优于红海榄。     

深圳福田无瓣海桑-海桑林能量的研究

在研究生物量、生产力的基础上,对深圳福田无瓣海桑-海桑林中2种红树植物海桑和无瓣海桑各组分的干重热值、林分能量现存量、年能量净固定量进行了研究．结果表明,各组分样品干重热值有一定的差异,树叶干重热值最高,纫根干重热值最低;海桑各组分样品干重热值比无瓣海桑相应组分稍高．林分能量现存量(1999年10月)为84774．72kJ·m^2,其中无瓣海桑种群能量现存量为54693．26kJ·m^-2,占林分总的64．54％,海桑种群能量现存量为30051．46kJ·m^-2,占林分总量的35．46％．林分凋落物的能量归还量(1999年)为24549．54kJ·m^-2·年^-1,其中无瓣海桑种群的能量归还量为17223．99kJ·m^-2·年^-1,占总林分的70．16％,海桑种群的能量归还量为7325．55kJ·m^-2·年^-1,占总林分的29．84％．林分能量净固定量为50391．4kJ·m^-2·年^-1,其中无瓣海桑种群和海桑种群的能量净固定量为分别为31778kJ·m^-2·年^-1和18613．4kJ·m^-2·年^-1．     

深圳福田红树林无瓣海桑+海桑群落N、P、K累积和循环

研究了深圳福田红树林无瓣海桑 +海桑群落的 N、P、K元素的累积和循环。结果表明 ,该群落 N、P、K元素的现存累积量分别为 :3 8694.92、 5 848.62、 5 0 861 .47mg/m2 ,其中地下部分分别占 2 8.5 9%、41 .77%、 42 .0 8%。该群落氮、磷、钾元素生物循环中 ,年吸收量分别为 :1 3 2 40 .0 95、 1 887.70 5、 2 0 73 6.1 1mg/m2 ;年归还量分别为 :62 70 .5 85、 979.1 75、 63 5 3 .948mg/m2 ;年存留量分别为 :6969.5 1、 90 8.5 3、 1 43 82 .1 62 mg/m2 ;周转期分别为 :7a、6a、9a。群落各组分的氮含量最高 ,磷含量最低。     

海桑属6种植物花粉形态兼化石花粉指南

利用光镜(LM)和电镜(SEM)观察和研究海桑属6种植物的花粉形态.详细描述海桑属(Sonneratia L．f．)花粉形态学特征并建立种间检索表.根据观察和分析结果,将6种植物花粉分为四种类型,即A类型(Sonneratia alba,S．×hainanensis,s．×gulngai)、B类型(S．caseolaris)、C类型(S．ovata)和D类型(S．apetala).进而讨论海桑属花粉形态特征对化石花粉的鉴别指南,以及在古生态学研究领域的应用价值.     

Population genetics of speciation in nonmodel organisms: I. Ancestral polymorphism in mangroves

The level of DNA polymorphism in the ancestral species at the time of speciation can be estimated using DNA sequences from many loci sampled from 2 or more extant species. The comparison between ancestral and extant polymorphism can be informative about the population genetics of speciation. In this study, we collected and analyzed DNA sequences of approximately 60 genes from 4 species of Sonneratia, a common genus of mangroves on the Indo-Pacific coasts. We found that the 3 ancestral species were comparable to each other in terms of level of polymorphism. However, the ancestral species at the time of speciation were substantially more polymorphic than the extant geographical populations. This ancestral polymorphism is in fact larger than, or at least equal to, the level of polymorphism of the entire species across extant geographical populations. The observations are not fully compatible with speciation by strict allopatry. We suggest that, at the time of speciation, the ancestral species consisted of interconnected but strongly divided geographical populations. This population structure would give rise to high level of polymorphism across species range. This approach of studying the speciation history by genomic means should be applicable to nonmodel organisms.     

海桑属红树植物次生木质部解剖特征极其对潮间带生境的适应

通过光学显微镜和扫描电子显微镜详细观察了相似生境条件下生长的海桑属(Sonneratia)植物以及低、高潮位生长的海桑(S. caseolaris)和杯萼海桑(S. alba)次生木质部的形态特征,应用Lasersharp软件测量了其次生木质部的数量特征.结果表明:海桑属植物次生木质部形态特征的特化是与潮间带生境相适应的,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.其特化结构主要包括: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、形状不规则的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)薄的纤维壁厚和宽的纤维腔径有利于水分的贮存,7)具胶质纤维.相似生境条件下生长的海桑属植物次生木质部数量特征的测量结果表明海桑和拟海桑水分输导效率高,但水分输导安全性差,而杯萼海桑水分输导效率低,但其输导安全性高.与高潮位生长的海桑和杯萼海桑相比,低潮位生长的海桑和杯萼海桑次生木质部导管分子更加"小型化"(有更小的导管分子长度、管孔弦向直径、管孔面积),有更高的导管聚合度和管孔密度,数量特征随生境不同的种内变动有利于海桑和杯萼海桑提高水分输导的安全性,但海桑和杯萼海桑输导安全性的获得是以牺牲水分输导的有效性为前提的.与生长在高潮位生境的海桑和杯萼海桑相比,低潮位生境生长的海桑和杯萼海桑的木材结构有更小的管孔面积,更厚的纤维壁,更低的导管比率和射线比率,更高的纤维比率,胶质纤维分布均匀且数量增加,这些特征有利于低潮位生境生长的海桑和杯萼海桑提高木材的韧性和强度,增强抗风浪冲击的能力.     

杯萼海桑和格氏海桑自然杂交的分子证据

Interspecific hybridization has been frequently observed in the mangrove genus Sonneratia. However, no natural hybridization has been reported between Sonneratia alba and S. griffithii to date, despite their overlapping distribution in the coast of Andaman Sea. In this study, cysteine proteinase inhibitor gene (cpi) from the nuclear genome, and two intergenic spacers (trnL-trnF and trnV-trnM) from the chloroplast genome, were sequenced to determine whether natural hybridization took place between the two species. Our results revealed two distinct types of cpi sequences from the putative hybrid matching those acquired from S. griffithii and S. alba, respectively. Sequencing of the chloroplast trnL-trnF and trnV-trnM regions showed that S. alba differed from S. griffithii by one nucleotide in each region, and the putative hybrid had the identical sequences with S. griffithii. Molecular data demonstrated clearly that there indeed existed natural hybridization between S. alba and S. griffithii, and that S. griffithii was the maternal parent in this hybridization event.     

海桑属红树植物离子积累、光合和抗氧化能力及相关性分析

以海桑属（SonneratiaLinn.f.）红树植物无瓣海桑（S.apetalaBuch.-Ham.）、海桑也S.caseolaris（Linn.）Engl.页、杯萼海桑（S.albaSmith）、卵叶海桑（S.ovataBacker）、拟海桑（S.×gulngaiN.C.DukeetB.R.Jackes）和海南海桑（S.×hainanensisW.C.Koetal.）为研究对象,比较了根际土壤和叶片中离子含量以及叶片光合和叶绿素荧光参数、叶绿素含量、抗氧化酶活性和O-·2产生速率的差异,并分析了叶片中Na＋和Cl-含量与部分生理生化指标的相关性。比较结果表明：海桑和拟海桑叶片中K＋含量最高、Na＋和Cl-含量均显著低于其他种类,但它们的根际土壤中Na＋和Cl-含量却较高。供试6种植物中仅海桑叶片对Cl-的富集系数小于1,各供试种类对K＋、Na＋、Cl-、Ca2＋和Mg2＋的富集系数均大于1;无瓣海桑对离子的富集系数由大至小依次为Mg2＋、K＋、Ca2＋、Na＋、Cl-,其他种类对离子的富集系数由大至小均依次为K＋、Ca2＋、Mg2＋、Na＋、Cl-。无瓣海桑和海桑的chla、chlb和总叶绿素含量差异不显著,但均高于其他种类;供试种类的chla/chlb比值均约为3,可能与海桑属植物为阳生植物有关。无瓣海桑的Pn、Tr和Gs均最高,而杯萼海桑的Pn、Tr和Gs均最低,但6种植物的Ci无明显差异。供试种类的Fv/Fm、qP、ETR和ΦPSⅡ均无显著差异,仅部分种类间的NPQ差异显著。无瓣海桑叶片中SOD、CAT和POD活性均显著高于其他种类,但O-·2产生速率最低;而卵叶海桑叶片中O-·2产生速率最高,其APX活性也均显著高于其他种类。相关性分析结果表明：供试6种植物叶片中Na＋和Cl-含量与Pn、qP、ΦPSⅡ和ETR负相关,与NPQ及SOD、CAT、APX和POD活性正相关。其中,Na＋含量与qP、ΦPSⅡ、ETR和SOD活性极显著相关,与NPQ和CAT活性显著相关;Cl-含量与SOD活性极显著相关,与qP、ΦPSⅡ和ETR显著相关。研究结果表明：供试海桑属植物对高盐生境有不同的耐性机?     

人工湿地污水处理系统三种红树植物抗性生理特性

研究了淡水条件下潜流型人工湿地污水处理系统中红树植物海桑、桐花树和木榄的抗性生理特性.结果表明,在为期1年的试验中,人工湿地污水处理系统3种红树植物超氧物歧化(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性持续升高并维持在较高水平,脯氨酸含量在7～9月达到最高水平,质膜透性没有明显的变化规律.对人工湿地与深圳福田自然保护区3种红树植物抗性生理指标进行比较,前者SOD、POD和CAT活性明显低于后者,脯氨酸含量前者明显高于后者,而丙二醛（MDA）含量和质膜透性则两者没有差别.3种红树植物能较好地适应淡水条件下潜流型人工湿地污水处理系统.