Isolation and characterization of chloroplast microsatellite markers in four mangrove species,Aegiceras corniculatum,Avicennia marina,Acanthus ilicifolius and Lumnitzera racemosa

One, three, seven, and six of polymorphic chloroplast microsatellite (cpSSR) markers were developed from four mangrove species, Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, and Lumnitzera racemosa, respectively. Characterization of 229, 509, 369, and 216 individuals of A. ilicifolius, A. corniculatum, A. marina, and L. racemosa, collected from different natural mangrove populations (A. ilicifolius, 6; A. corniculatum, 14; A. marina, 10; L. racemosa, 6) in the southern coastline of China showed that these loci provide cpSSR markers with polymorphisms ranging from two to four alleles per locus and gene diversity between 0.005 and 0.675. Combining the polymorphic cpSSR loci of each species, 3, 5, 11, and 4 of cpSSR haplotypes were separately detected in populations of A. ilicifolius, A. corniculatum, A. marina, and L. racemosa in the southern coastline of China. These cpSSR markers will be useful for analyzing the maternal lineage distributions and population genetic structures of these four species.     

Development and characterization of ten new microsatellite markers in a mangrove tree species Bruguiera gymnorrhiza (L.)

Bruguiera gymnorrhiza is an ecologically and somewhat economically important mangrove tree species. We isolated 10 polymorphic microsatellite loci from B. gymnorrhiza using a dual‐suppression polymerase chain reaction (PCR) technique. These loci provided microsatellite markers with polymorphism of two to five alleles per locus within 216 individuals from nine natural populations of B. gymnorrhiza on Iriomote Island, the Sakishima Islands, Japan. The expected and observed heterozygosities ranged from 0.220 to 0.720 and from 0.104 to 0.447, respectively.     

Isolation and characterization of eight compound microsatellite markers in a mangrove tree Kandelia candel (L.) Druce

Kandelia candel is an important mangrove tree species of family Rhizophoraceae. Here we isolated eight codominant compound microsatellite simple sequence repeat (SSR) loci from K. candel. Our isolated loci provided compound SSR markers with polymorphism of three to 11 alleles per locus. The expected and observed heterozygosities ranged from 0.230 to 0.887 and from 0.083 to 1.00, respectively. These markers would be the useful tools for analysing questions concerning population genetic structure and mating system of K. candel.     

Growth and physiological responses of two mangrove species (Bruguiera gymnorrhiza and Kandelia candel) to waterlogging

Effects of duration of waterlogging on growth and physiological responses of two mangrove species, Bruguiera gymnorrhiza and Kandelia candel, were investigated. The relative growth rate of B. gymnorrhiza decreased significantly with waterlogged time, with the highest value found for drained plants and the lowest in plants under 12 weeks waterlogging. On the contrary, no significant difference was found between waterlogged and drained K. candel plants. The shoot to root biomass ratio of K. candel increased when subjected to 8 or 12 weeks waterlogging but little change was recorded in B. gymnorrhiza, indicating a shift in biomass allocation from roots to shoots in K. candel under prolonged waterlogging but not in B. gymnorrhiza. These different growth responses between the two mangrove species supported the hypothesis that K. candel is more tolerant to waterlogging than B. gymnorrhiza. Under 12 weeks waterlogged treatment, root oxidase activity significantly decreased in B. gymnorrhiza but increased in K. candel. Chlorophyll contents of K. candel increased more rapidly in response to waterlogging than B. gymnorrhiza. Activities of both peroxidase and superoxide dismutase increased significantly in leaves of K. candel when the waterlogging period was longer than 8 weeks, while only the peroxidase activity of B. gymnorrhiza showed a significant increase, indicating that K. candel had stronger resistance to the oxidant damage resulting from waterlogging. These physiological indicators further supported the hypothesis that K. candel is more tolerant to waterlogging than B. gymnorrhiza.     

Cloning and functional expression of cycloartenol synthases from mangrove species Rhizophora stylosa Griff. and Kandelia candel (L.) Druce

To obtain cDNAs encoding oxidosqualene cyclase (OSC), we cloned two cDNAs, KcCAS and RsCAS, from roots of Kandelia candel (L.) Druce and leaves of Rhizophora stylosa Griff. by homology based PCR method respectively. The deduced amino acid sequences of both OSCs showed 82% homology to cycloartenol synthases from Lotus japonicus (OSC5) and Ricinus cummunis (RcCAS), suggesting that these are cycloartenol synthases of K. candel and R. stylosa. The genes obtained were expressed in a lanosterol synthase deficient Saccharomyces cerevisiae (ERG7) strain, GIL77. GC-MS analysis identified the accumulated reaction product in the yeast transformant to be cycloartenol, indicating that both KcCAS and RsCAS encode cycloartenol synthase.     

Mating system,pollen and propagule dispersal,and spatial genetic structure in a high-density population of the mangrove tree Kandelia candel

Mangrove tree species form ecologically and economically important forests along the tropical and subtropical coastlines of the world. Although low intrapopulation genetic diversity and high interpopulation genetic differentiation have been detected in most mangrove tree species, no direct investigation of pollen and propagule dispersal through paternity and/or parentage analysis and spatial genetic structure within populations has been conducted. We surveyed the mating system, pollen and propagule dispersal, and spatial genetic structure in a natural population of Kandelia candel, one of the typical viviparous mangrove tree species, using nuclear and chloroplast microsatellite markers. High diversity and outcrossing rates were observed. Paternity and parentage analysis and modelling estimations revealed the presence of an extremely short-distance component of pollen and propagule dispersal (pollen: 15.2 ± 14.9 m (SD) by paternity analysis and 34.4 m by modelling; propagule: 9.4 ± 13.8 m (SD) by parentage analysis, and 18.6 m by modelling). Genetic structure was significant at short distances, and a clumped distribution of chloroplast microsatellite genotypes was seen in K. candel adults. We conclude that the K. candel population was initiated by limited propagule founders from outside by long-distance dispersal followed by limited propagule dispersal from the founders, resulting in a half-sib family structure.     

Reproductive biology and population genetic structure of Kandelia candel (Rhizophoraceae), a viviparous mangrove species

The pollination biology, mating system, and population genetic structure of Kandelia candel were investigated. Field observations on its pollination and reproductive biology suggested that this species is pollinator dependent for fruit set, and bee activities can lead to substantial geitonogamous selfing. Quantitative analysis of the mating system parameters was performed using progeny arrays assayed for allozyme markers. Multilocus outcrossing rates (t(m)) were estimated to be 0.697 ± 0.091 and 0.797 ± 0.062 in two populations. In comparison to other plant species with mixed-mating system, the level of allozyme variation was very low in the 13 populations sampled along the coastlines of Hong Kong. At the species level, the proportion of polymorphic loci was 20%, number of alleles per locus was 1.2, and heterozygosity was 0.0362. The total gene diversity was primarily distributed within populations (H(S )= 0.0339), and the coefficient of genetic differentiation among populations was low (G(ST )= 0.064). This pattern of population genetic structure suggests that gene flow, primarily in the form of water-dispersed seedlings in viviparous mangrove species, is not as limited as previously thought. However, microgeographic pattern in allele frequency at the marker loci could still be detected between the western and eastern coastal populations.     

Development of microsatellite markers in Rhizophora stylosa using a dual‐suppression‐polymerase chain reaction technique

Rhizophora stylosa is an ecologically important mangrove tree species that is found in tropical and subtropical regions. We isolated five polymorphic microsatellite loci from R. stylosa using a dual‐suppression‐polymerase chain reaction technique. These loci provided microsatellite markers with polymorphism of four alleles in each locus for overall population. The mean expected heterozygosities ranged from 0.113 to 0.473.     

红树植物秋茄和桐花树抗寒力的越冬变化

采用电导法定量测定了福建省九龙江口红树植物秋茄和桐花树抗寒力的越冬变化 ,探讨了抗寒力与水分、叶绿素、可溶性蛋白质含量及过氧化物酶活性的相关性 .结果表明 ,1 988年 9月至 1 989年 4月越冬期间 ,秋茄和桐花树抗寒力随气温下降而增强 ,分别于1月和 1 2月达到最大 ,低温处理 1h ,半致死温度为 - 9.3℃和 - 9.0℃ ;其后 ,抗寒力随气温回升而迅速下降 .冬季秋茄和桐花树抗寒力的提高与束缚水含量增加或自由水含量减少密切相关 ,并伴随可溶性蛋白质含量的增加和过氧化物酶活性的增强 .束缚水与自由水、叶绿素a与b含量的比值变化可以反映红树植物抗寒力变化 :两种比值越高 ,抗寒力越强 .     

木榄和秋茄对水渍的生长与生理反应的比较研究

研究了不同水渍时间对两种红树植物木榄(Bruguiera gymnorrhiza(L.)Lam)和秋茄(Kandelia candel(L.)Druce)的生长与生理的影响.随着淹水时     

Molecular cloning and functional expression of a multifunctional triterpene synthase cDNA from a mangrove species Kandelia candel (L.) Druce

Homology based PCRs with degenerate primers designed from the conserved sequences among the known oxidosqualene cylases (OSCs) have resulted in cloning of a triterpene synthase (KcMS) from the young roots of Kandelia candel (L.) Druce (Rhizophoraceae). KcMS consists of a 2286 bp open reading frame, which codes for 761 amino acids. The deduced amino acid sequence showed 79% homology to a lupeol synthase from Ricinus communis suggesting it to be a lupeol synthase of K. candel. KcMS was expressed in a lanosterol synthase deficient yeast with the expression vector pYES2 under the control of GAL1 promoter. GC-MS analysis showed that the transformant accumulated a mixture of lupeol, beta-amyrin and alpha-amyrin in a 2:1:1 ratio, indicating that KcMS encodes a multifunctional triterpene synthase, although it showed high sequence homology to a R. communis lupeol synthase. This is the first OSC cloning from mangrove tree species.     

Tannin Dynamics of Propagules and Leaves of Kandelia candel and Bruguiera gymnorrhiza in the Jiulong River Estuary, Fujian, China

Changes in the total phenolics, condensed tannins (CT), protein-precipitable phenolics content and protein precipitation capacity were determined on a series of mangrove leaves from two true viviparous mangrove species (Kandelia candel and Bruguiera gymnorrhiza) at various stages of development and decomposition in the Jiulong River Estuary, Fujian, China. Similar measurements were also done for the propagules at different developmental stages. The results showed that the total phenolics, extractable condensed tannins, total condensed tannins, protein-precipitable phenolics content and protein precipitation capacity in young leaves were higher than those in mature and senescent leaves. Tannin dynamics during leaf decomposition varied with species, and the rapid loss of phenolics observed during decomposition can be ascribed to leaching and degradation. Protein-bound CT and fibre-bound CT tended to increase with leaf decomposition, with CT binding more strongly to protein than to fibre. Protein-bound CT was higher than fibre-bound CT with the exception of mature leaves. Total phenolics, extractable CT and protein-precipitable phenolics contents in flower tissues were relatively lower than those in hypocotyls at different developmental stages. Protein precipitation capacity fluctuated with the development of propagules. Increases in nitrogen in decaying litter, and declines in contents of total phenolics and total condensed tannins of detritus support the general conclusion that decomposing mangrove detritus can be a more palatable heterotrophic substrate than living leaves.     

红树植物木榄幼树斑块形状的分形分析

应用分形理论分析了山口国家级红树林自然保护区木榄幼树斑块形状的分形特征。木榄幼树斑块在整体水平上的分形维数为 1 .1 2 ,而单个斑块的分形维数介于 1 .1 7～ 1 .3 7之间。分形维数的大小与斑块形状的复杂程度密切相关。频谱法和周长 -面积法都适用于分析幼树斑块形状的分形特征。     

Development and polymorphism of simple sequence repeat DNA markers for Bruguiera gymnorrhiza (L.) Lamk

Microsatellite markers of Bruguiera gymnorrhiza were developed. Fifty‐four of 161 clones were found to contain microsatellite repeats. Primer pairs were designed for 20 of these clones according to their sequence data. Of these, seven primers showed polymorphism for 32 individuals from Iriomote Island, Japan. Two to five alleles per locus were detected, and the observed heterozygosities ranged from 0.031 to 0.500. Cross‐species amplification using five of the seven primers also worked well for B. cylindrica and B. parviflora. Because our previous study reported very low levels of genetic diversity for allozymes in the same Iriomote population, these microsatellite markers should be a powerful tool for various kinds of genetic analysis.     

广西红海榄红树林C,H,N的动态研究

探讨了广西英罗湾７０年生红海榄红树林Ｃ、Ｈ、Ｎ含量、现存贮量、年能量及年Ｏ２的净生产,结果表明,红海榄植物体不同组分,Ｃ、Ｈ、Ｎ含量范围分别为４３．８６－５１．６５、４．３５－５．７２和０．２８－１．４４％。     

Development and polymorphism of simple sequence repeat DNA markers for Kandelia candel (L.) Druce

Microsatellite markers of Kandelia candel were developed. Forty‐nine clones yielded strong positive signals among 331 clones hybridized to repetitive sequence probes. Primer pairs were designed for 19 of these positive clones according to their sequence data. Five of the primer pairs showed polymorphism for 16 individuals from Amami‐O‐Shima Island, Japan. Three to nine alleles per locus were detected, and the observed heterozygosities ranged from 0.250 to 0.938. Because our previous study reported very low level of genetic diversity for allozymes in the same Amami population, these microsatellite markers should be powerful tools for the analysis of genetic structure.     

Effects of copper on growth, radial oxygen loss and root permeability of seedlings of the mangroves Bruguiera gymnorrhiza and Rhizophora stylosa

Purpose

Mangrove wetlands have experienced significant contaminant input such as copper (Cu), aggravated by rapid urban development. This study aimed to investigate the possible function of root permeability in metal detoxification.

Methods

Pot trials were conducted to evaluate the responses of root permeability in relation to metal (Cu) exposure in seedlings of two mangroves: Bruguiera gymnorrhiza and Rhizophora stylosa.

Results

Copper inhibited plant growth and root permeability of the two species significantly (due to decreases in root porosity, thickening of exodermis and increases in lignification), leading to a significant reduction in radial oxygen loss (ROL). A negative correlation between soil Cu and ROL from root tip was also observed. The observed metal uptake by excised roots further indicated that increased lignification would directly prevent excessive Cu from further entering into the roots.

Conclusions

In summary, the two mangroves reacted to Cu by producing an impermeable barrier in roots. Such an inducible barrier to ROL is likely to be an adaptive strategy against Cu toxicity. This study reveals new evidence of a structural adaptive strategy for metal tolerance by mangrove plants.     

红树植物秋茄和红海榄叶片元素含量及季节动态的比较研究

研究了福建九龙江口秋茄（Kandelia candel L.）和红海榄（Rhizophora stylosa G.）成熟叶片N、P、K、Na、Ca、Mg和CI等元素含量的季节变化和元素间的关系。结果表明秋茄和红海榄同为红树科树种,生境相同且同属拒盐植物,但在元素积累及季节变化模式上存在较大差别。秋茄和红海榄叶片高盐分和Ca含量及低K／Na比,这是我们对盐渍生境的一种适应。秋茄无机渗透调节剂（主要指K^ 、Na^ 、Ca^2 、Mg^2 和CI^-）含量夏季高于冬季,而红海榄与之完全相反。秋茄能够通过主动积累有机渗透调节剂来适应低温,而红海榄不能。对秋茄和红海缆抗寒机制进行了讨论。     

Isolation and characterization of microsatellite loci in the red mangrove Rhizophora mangle (Rhizophoraceae) and its related species

Fourteen microsatellite markers were isolated from the red mangrove Rhizophora mangle (Rhizophoraceae), a widely distributed mangrove plant in the New World and West Africa. The range of expected heterozygosity of these markers was 0.000–0.672 in the two populations of R. mangle. Cross-species testing was examined for five other species of Rhizophora, and Kandelia candel and Bruguiera gymnorrhiza. All 14 markers could be amplified in R. samoensis, thirteen in R. racemosa, and six markers in all other species of Rhizophora. Our findings greatly increase the utility of these markers.     

Analyses of genetic population structure of two ecologically important mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata from different river basins of Iriomote Island of the Ryukyu Archipelago, Japan

We analyzed nuclear and chloroplast microsatellite makers to assess genetic diversity and examine genetic structure of two mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata recovered from nine major river basins of Iriomote Island of the Ryukyu Archipelago, Japan. The average number of alleles per nuclear locus per population was 2.6 in B. gymnorrhiza and 1.7 in K. obovata. Bayesian clustering analysis using InStruct identified two genetic clusters in B. gymnorrhiza and three clusters in K. obovata. Chloroplast microsatellites revealed two dominant haplotypes from B. gymnorrhiza and three haplotypes from K. obovata. The overall result suggests low genetic diversity for both species. AMOVA for nuclear microsatellites showed 9.3?% of population variation in B. gymnorrhiza. Although genetic differentiation between several populations was significant in this species, F _ST suggested low to moderate level of differentiations between most of the populations. Distribution of genetic clusters and chloroplast haplotypes also suggested weak differentiations among B. gymnorrhiza populations. In K. obovata, population variation was, however, relatively high (27.8?%). The high differentiation between K. obovata populations was also suggested from the F _ST and genetic clusters from nuclear microsatellites, and chloroplast haplotypes. A significant correlation between chloroplast genetic distances and coastline distances as well as haplotype distributions for both species suggest that propagules from each species mostly disperse to the neighboring river basins. While significant F _IS and higher percentage of admixed clusters from nuclear microsatellites suggested inbreeding, continual gene exchange by propagule dispersal among populations especially among neighboring populations was suggested for both species from maternally inherited chloroplast microsatellites analyses.