不同土壤雷竹盆栽苗地下茎分枝数量特征及其分布格局

为了探究竹子分株系统构建过程及其与人工经营的关系,本文对雷竹(Phyllostachys praecox C. D. Chu et C. S. Chao ‘Prevernalis’)不同年龄母竹、不同覆盖年限竹林进行土壤盆栽实验,比较了各处理竹苗地下茎分枝生长差异。结果显示：在盆栽竹苗分株系统构建过程中,地下茎以竹鞭分枝为主;2年生母竹盆栽苗地下茎分枝数量普遍高于1年生盆栽苗,且地下茎分枝表现出随竹林土壤覆盖年限增加而减少的趋势;盆栽苗地下茎分枝主要分布于第Ⅱ、Ⅲ、Ⅳ分枝的鞭中位置;1年生母竹盆栽苗地下茎分枝以第Ⅱ分枝级别的鞭中、鞭梢部位为多,而2年生母竹盆栽苗则以第Ⅲ分枝级别的鞭中、鞭梢部位为多;随土壤覆盖年限增加,地下茎分枝偏向分布于较为靠前的分枝级别。研究发现,母竹盆栽苗分株系统的构建主要采取了扩大地下分枝的策略,其2年生母竹与竹鞭中部着生侧芽的分枝生长对分株系统拓展贡献率较大;竹林土壤覆盖时间越久越不利于地下茎分枝。由于竹子分株系统具有时空拓展性,其地下茎分枝生长特征尚需持续观察。     

蜡梅小孢子发生和花粉形成的研究

通过对蜡梅小孢子发生和花粉形成的研究,结果表明：蜡梅幼小花药中的多列孢原细胞经造孢细胞发良为小孢子母细胞。减数分裂为同时型。四分体呈四面体型排列,同时观察了小孢子在发育过程中液泡的动态变化。成熟花粉为２－细胞型。花药壁的发育为双子叶型。花药壁由５－６层细胞组成,腺质绒毡层。花粉具有异型性现象。     

基于SSR分子标记的175份蜡梅种质遗传多样性分析和指纹图谱构建

理清蜡梅品种资源、构建指纹图谱是推动蜡梅科学研究和产业发展的重要基础。利用简单重复序列(simple sequence repeats, SSR)分子标记技术,对鄢陵地区175个蜡梅(Chimonanthus Praecox L.)品种(系)的遗传多样性进行了研究,使用NTSYSpc 2.1软件中的UPDM聚类方法分析品种间的遗传多样性。利用基于贝叶斯模型的Structure v2.3.3软件解析175份种质的遗传结构。通过一般线性模型(general linear model, GLM)对性状和标记进行关联分析。在遗传多样性分析中,平均等位基因数(number of alleles, Na)为6.857,平均期望杂合度(heterozygosity, He)为0.496 3,平均观测杂合度(observed heterozygosity, Ho)为0.503 7,蜡梅Nei’s平均基因多样性指数为0.494 9,平均Shannon信息指数为0.995 8,表明鄢陵地区蜡梅群体内具有较丰富的遗传多样性。群体结构和UPDM聚类分析均表明可将175个品种(系)分为7个类群。在GLM模型中有15个标记位点与8个表型性状显著(P<0.05)关联,表型变异解释范围为14.90%−36.03%。利用11对多态信息含量(polymorphic information content, PIC)最高的引物,构建175份蜡梅品种(系)资源SSR标记的指纹图谱。本研究综合分析了鄢陵地区蜡梅的遗传多样性与SSR分子标记,并构建了蜡梅核心种质资源库,为蜡梅新优品种选育、品种鉴定、资源保护与利用等工作提供理论支撑。     

Isolation and Structural Determination of the Antifouling Diketopiperazines from Marine-Derived Streptomyces praecox 291-11

Marine derived actinomycetes constituting 185 strains were screened for their antifouling activity against the marine seaweed, Ulva pertusa, and fouling diatom, Navicula annexa. Strain 291-11 isolated from the seaweed, Undaria pinnatifida, rhizosphere showed the highest antifouling activity and was identified as Streptomyces praecox based on a 16S rDNA sequence analysis. Strain 291-11 was therefore named S. praecox 291-11. The antifouling compounds from S. praecox 291-11 were isolated, and their structures were analyzed. The chemical constituents representing the antifouling activity were identified as (6S,3S)-6-benzyl-3-methyl-2,5-diketopiperazine (bmDKP) and (6S,3S)-6-isobutyl-3-methyl-2,5-diketopiperazine (imDKP) by interpreting the nuclear magnetic resonance and high-resolution mass spectroscopy data. Approximately 4.8 mg of bmDKP and 3.1 mg of imDKP were isolated from 1.2 g of the S. praecox 291-11 crude extract. Eight different compositions of culture media were investigated for culture, the TBFeC medium being best for bmDKP and TCGC being the optimum for imDKP production. Two compounds respectively showed a 17.7 and 21 therapeutic ratio (LC₅₀/EC₅₀) to inhibit zoospores, and two compounds respectively showed a 263 and 120.2 therapeutic ratio to inhibit diatoms.     

Comparison of heavy metal phytoremediation in monoculture and intercropping systems of Phyllostachys praecox and Sedum plumbizincicola in polluted soil

A bamboo species (Phyllostachys praecox) and a Cd/Zn hyperaccumulator (Sedum plumbizincicola) were tested under different planting systems to compare their heavy metal phytoremediation ability. P. praecox (MP), S. plumbizincicola (MS) and P. praecox × S. plumbizincicola (IPS) plantations were established in Cu, Zn, and Cd-contaminated soil. Soil properties and heavy metal contents in plants were determined and compared after four years of plantation establishment. The rankings of available and total metal contents in soil layers were MP > MS > IPS (0–20 cm) and MP > IPS > MS (20–40 cm, except for Cu), respectively. The Cu and Zn contents in mature bamboo tissues were significantly lower, but the Cd contents in bamboo tissues (except for leaves) higher, in the IPS than in the MP. The bioconcentration and the translocation factors in most of bamboo tissues showed an increasing trend from the MP to the IPS. Heavy metal distribution in plants is greatly affected by the planting patterns. The tested intercropping system of two plant species showed higher biomass productivity, implying more heavy metals can be removed from the soil through the harvesting of plants. Therefore, the IPS leads to significant improvement of soil phytoremediation.     

闽东北雷竹尾梢长度与笋产量关系的初步研究

采用随机区组试验设计法对雷竹保留尾梢长度与笋产量的关系进行研究,通过对比分析表明,钩梢比不钩梢的笋产量高,其中以保留竹尾长度1/3的笋产量最高,经济效益最好。     

Effects of domestication on genetic diversity in Chimonanthus praecox: Evidence from chloroplast DNA and amplified fragment length polymorphism data

Chimonanthus praecox (L.) Link is a widely cultivated endemic winter-flowering plant in China that has a long cultivation history. Genetic diversity and genetic structure were compared between wild and cultivated groups to reveal the geographic origin of the cultivated genotypes using chloroplast DNA (cpDNA) sequences and amplified fragment length polymorphism (AFLP) markers. Nine haplotypes were identified using three combined chloroplast fragments. Based on chloroplast data, the wild group showed greater genetic variation and genetic differentiation and a lower measure of gene flow compared to the cultivated group. The AFLP markers also supported this trend. More than 40% of the cpDNA haplotypes were shared between wild and cultivated groups, with shared haplotypes originating from multiple wild populations, suggesting multiple origins of cultivated plants. Moreover, principal coordinate analysis, UPGMA, and structure analysis of AFLP markers revealed that two wild populations clustered with most of the cultivated populations of Ch. praecox, suggesting that most of the cultivated populations mainly originated from these two populations. The combined cpDNA and AFLP results indicated that modern cultivated Ch. praecox experienced multiple events of origin involving two geographic origins, eastern China (Tianmu Mountain) and southwestern China (the border of Hunan–Guangxi–Sichuan–Guizhou).     

Relationship between soil nutrient availability and plant species richness in a tropical semi‐arid environment

Question: What is the relationship between soil fertility and plant species richness in the ‘fertile islands’ occurring beneath two species of legume (Cercidium praecox and Prosopis laevigata)? Location: Tehuacán‐Cuicatlán region, central Mexico. Methods: Plant richness was measured in three micro‐environments (below canopies of C. praecox, below canopies of P. laevigata and in areas without canopies). The concentration of soil nutrients (C, N and P), C and N in the microbiota, and processes of ecosystem functioning (net C mineralization rate and N mineralization) were measured. The relationship between soil variables and plant richness were assessed with ANCOVAs. Results: Soil nutrients and species richness increases markedly under fertility islands. There were higher concentrations of C and N in the soil, faster rates of C mineralization, and higher species richness under P. laevigata canopies. The relationship between soil fertility and species richness was always positive except for total N, ammonium and net C mineralization rate under C. praecox, and for available P under P. laevigata. Conclusions: The sign of the relationship between soil fertility and species richness varies according to the nutrient and the micro‐environment. Positive relationships could result from between species complementarity and facilitation. Negative relationships could be explained by a specific limitation threshold for some soil resources (P and N for plants and C for the soil microbiota) which eliminate the possibilities of between species complementarity and facilitation above that threshold. As in all observational studies, these relationships should be considered only correlational.     

雷竹覆盖物分解速率及其硅含量的变化

以冬季地表覆盖增温为核心的雷竹早产高效栽培技术被广泛应用于我国亚热带地区的雷竹(Phyllostachys praecox)产区。为探明雷竹覆盖物（稻草和竹叶）的分解速率及在分解残余物中硅含量的年动态变化规律,在浙江临安市雷竹主产区采用分解管法进行了覆盖物分解试验。试验结果表明,稻草、竹叶的月平均分解速率分别为8.5 %和11.9 %,在1a内分别分解了67.5 %和79.3 %。在1年的分解过程中,稻草和竹叶C含量随时间的推移而下降,而N含量则随时间的推移而增加,两者的C/N比总体都呈现下降的趋势,但在试验初期前者的下降幅度显著大于后者。稻草、竹叶覆盖残余物中的Si含量随着分解时间的增加而增加,并都在12月达到最大值81.8 g?kg-1和80.0 g?kg-1。稻草、竹叶的分解残余物中硅含量与铝含量或铁含量之间均呈极显著正相关（p<0.01）,但与磷含量无显著相关性(p>0.05)。