缙云山常绿阔叶林不同演替阶段植物生活型谱比较研究

采用Raunkiner生活型分类系统,对缙云山常绿阔叶林不同演替阶段植物的生活型进行统计,编制了生活型谱,并与其他亚热带地区常绿阔叶林相比较。结果表明,缙云山植被属典型的中亚热带常绿阔叶林植被,高位芽植物占绝对优势,达80％以上,其中小高位芽植物最多,中高位芽与矮高位芽植物次之,藤本植物较丰富。缙云山不同演替阶段的植物的生活型谱不同。随着进展演替阶段的逐渐更替,高位芽植物的比例呈递增趋势,地面芽植物、地下芽植物成分有所减少。高位芽的常绿树种会逐渐代替针叶树种。     

Long noncoding RNAs involve in resistance to Verticillium dahliae,a fungal disease in cotton

Long noncoding RNAs (lncRNAs) have several known functions in plant development, but their possible roles in responding to plant disease remain largely unresolved. In this study, we described a comprehensive disease‐responding lncRNA profiles in defence against a cotton fungal disease Verticillium dahliae. We further revealed the conserved and specific characters of disease‐responding process between two cotton species. Conservatively for two cotton species, we found the expression dominance of induced lncRNAs in the Dt subgenome, indicating a biased induction pattern in the co‐existing subgenomes of allotetraploid cotton. Comparative analysis of lncRNA expression and their proposed functions in resistant Gossypium barbadense cv. ‘7124’ versus susceptible Gossypium hirsutum cv. ‘YZ1’ revealed their distinct disease response mechanisms. Species‐specific (LS) lncRNAs containing more SNPs displayed a fiercer inducing level postinfection than the species‐conserved (core) lncRNAs. Gene Ontology enrichment of LS lncRNAs and core lncRNAs indicates distinct roles in the process of biotic stimulus. Further functional analysis showed that two core lncRNAs, GhlncNAT‐ANX2‐ and GhlncNAT‐RLP7‐silenced seedlings, displayed an enhanced resistance towards V. dahliae and Botrytis cinerea, possibly associated with the increased expression of LOX1 and LOX2. This study represents the first characterization of lncRNAs involved in resistance to fungal disease and provides new clues to elucidate cotton disease response mechanism.     

NMR imaging of root water distribution in intact Vicia faba L plants in elevated atmospheric CO2

The effect of elevated atmospheric CO₂ on water distribution in the intact roots of Vicia faba L. bean seedlings grown in natural soil was studied noninvasively with proton (¹H) nuclear magnetic resonance (NMR) imaging. Exposure of 24-d-old plants to atmospheric CO₂-enriched air at 650 cm³ m^?3 produced significant increases in water imaged in upper roots, hypogeal cotyledons and lower stems in response to a short-term drying-stress cycle. Above ground, drying produced negligible stem shrinkage and stomatal resistance was unchanged. In contrast, the same drying cycle caused significant depletion of water imaged in the same upper root structures in control plants subject to ambient CO₂ (350 m³ m^?3), and stem shrinkage and increased stomatal resistance. The results suggest that inhibition of transpiration caused by elevated CO₂ does not necessarily result in attenuation of water transport from lower root structures. Inhibition of water loss from upper roots and lower stem in elevated CO₂ environments may be a mitigating factor in assessing deleterious effects of greenhouse changes on crops during periods of dry climate.     

都江堰地区三种壳斗科植物的种子库及其影响因素研究

于2000年9月～12月,在都江堰地区对原生林和次生林中3种优势壳斗科(Fagaceae)植物的种子雨和土壤种子库进行了研究,并提出基于种子雨和土壤种子库测定的种子虫蛀率、种子存活率、脊椎动物捕食率和种子发霉率的估计方法.结果表明①种子雨持续时间较长,3种壳斗科植物种子雨的高峰期在原生林和次生林中略有差异;②3种壳斗科植物的种子产量很低,种子雨散落的平均密度不大.在原生林,栓皮栎(Quercu.svariabilis)、抱树(Q serrata)和栲树(Castanopsis fargesu)种子下落的平均密度分别为2 3±3.85个/n2,6.5±17.43个/m2和1.9±5.21个/m2;而在次生林则分别为2.4±3 47个/m2,6.5±13.55个/m2和0 3±1.35个/m2;③土壤种子库中,栓皮栎在原生林中没有存留完好的种子,而在次生林的落叶层中存留有少量完好的种子(0 15±0.37个/m2); 树在原生林和次生林中都存留有少量完好的种子(分别为0.20±0.70个/m2和0.10±0.31个/m2)和少量萌发种子(分别为0.50±1.82个/m2和0.20±0 89个/m2);但在土壤中未发现有栲树的种子.绝大部分的种子存留在落叶层,而存留在0～2 cm和2～10 cm土层中的种子极少;④定量测定了发霉、虫蛀和脊椎动物捕食对2种壳斗科植物种子命运的影响,发现脊椎动物捕食是影响种子库的主要因子;虫蛀率虽增加种子的发霉率,但同时也减少脊椎动物捕食率;种子较大的栓皮栎种子的存活率低于种子较小的树种子的存活率.     

浙江天童常绿阔叶林演替过程凋落物数量及分解动态

浙江天童常绿阔叶林演替过程森林凋落物量呈增长趋势,其中：乔木叶比例最大,其它器官组分在不同演替阶段的比例不一致,灌木叶和草本、树皮比例随着演替进程而呈减少趋势,树枝和繁殖器官则呈增大趋势。以分解袋法测得凋落物年失重率和指数方程模拟的分解系数Ｋ在演替过程中均呈增长趋势,这与年凋落物数量变化趋势相似。可见,随着演替进程,生物循环加快,群落自肥能力增强。     

云南省哀牢山中山湿性常绿阔叶林萌生现象的初步研究

在森林树木受到人为或自然破坏以后,残留植物体的萌生是一个普遍存在的现象。据Kauffman〔1〕和Khan〔2〕等人在热带地区的研究,通过萌生形成的植株与通过种子萌发形成的植株相比,前者具有更快的生长速度,而且通过其原有的强大根系,能更有效地利用土壤中的养分资源,同时对环境也具有更强的适应能力。这些都构成了萌生植株在生长上的优势,使其在种群竞争中处于有利的地位。由此可见,萌生过程在植被恢复和自然更新中起到了重要的作用。近年来,关于植被萌生的研究在国外已得到越来越多的重视〔3～8〕,而在国内至今还未见到这方面的正式报道。…     

接合转移诱动系统在遗传分析和体内基因操作中的应用

接合转移诱动系统在遗传分析和体内基因操作中的应用赵巍,张成刚,蔺继尚（中国科学院沈阳应用生态研究所,１１００１５）细菌间ＤＮＡ的转移主要有转化、转导、接合和原生质体融合等几种形式。接合是通过供体菌和受体菌完整细胞间的直接接触,而传递大段ＤＮＡ的方法,...     

Effects of forest types on leaf functional traits and their interrelationships of Pinus massoniana coniferous and broad‐leaved mixed forests in the subtropical mountain,Southeastern China

Leaf functional traits are widely used to detect and explain adaptations that enable plants to live under various environmental conditions. This study aims to determine the difference in leaf functional traits among four forest types of Pinus massoniana coniferous and broad‐leaved mixed forests by leaf morphological, nutrients, and stoichiometric traits in the subtropical mountain, Southeastern China. Our study indicated that the evergreen conifer species of P. massoniana had higher leaf dry matter content (LDMC), leaf C content, C/N and C/P ratios, while the three deciduous broad‐leaved species of L. formosana, Q. tissima, and P. strobilacea had higher specific leaf area (SLA), leaf N, leaf P nutrient contents, and N/P ratio in the three mixed forest types. The results showed that the species of P. massoniana has adapted to the nutrient‐poor environment by increasing their leaf dry matter for higher construction costs thereby reducing water loss and reflects a resource conservation strategy. In contrast, the three species of L. formosana, Q. tissima, and P. strobilacea exhibited an optimized resource acquisition strategy rather than resource conservation strategy in the subtropical mountain of southeastern China. Regarding the four forest types, the three mixed forest types displayed increased plant leaf nutrient contents when compared to the pure P. massoniana forest, especially the P. massoniana–L. formosana mixed forest type (PLM). Overall, variation in leaf functional traits among different forest types may play an adaptive role in the successful survival of plants under diverse environments because leaf functional traits can lead to significant effects on leaf function, especially for their acquisition of nutrients and use of light. The results of this study are beneficial to reveal the changes in plant leaf functional traits at the regional scale, which will provide a foundation for predicting changes in leaf traits and adaptation in the future environment.     

Forecasting intensifying disturbance effects on coral reefs

Anticipating future changes of an ecosystem's dynamics requires knowledge of how its key communities respond to current environmental regimes. The Great Barrier Reef (GBR) is under threat, with rapid changes of its reef‐building hard coral (HC) community structure already evident across broad spatial scales. While several underlying relationships between HC and multiple disturbances have been documented, responses of other benthic communities to disturbances are not well understood. Here we used statistical modelling to explore the effects of broad‐scale climate‐related disturbances on benthic communities to predict their structure under scenarios of increasing disturbance frequency. We parameterized a multivariate model using the composition of benthic communities estimated by 145,000 observations from the northern GBR between 2012 and 2017. During this time, surveyed reefs were variously impacted by two tropical cyclones and two heat stress events that resulted in extensive HC mortality. This unprecedented sequence of disturbances was used to estimate the effects of discrete versus interacting disturbances on the compositional structure of HC, soft corals (SC) and algae. Discrete disturbances increased the prevalence of algae relative to HC while the interaction between cyclones and heat stress was the main driver of the increase in SC relative to algae and HC. Predictions from disturbance scenarios included relative increases in algae versus SC that varied by the frequency and types of disturbance interactions. However, high uncertainty of compositional changes in the presence of several disturbances shows that responses of algae and SC to the decline in HC needs further research. Better understanding of the effects of multiple disturbances on benthic communities as a whole is essential for predicting the future status of coral reefs and managing them in the light of new environmental regimes. The approach we develop here opens new opportunities for reaching this goal.     

UDP-galactose 4′-epimerase from vicia faba seeds

UDP-Galactose 4′-epimerase was purified ca 800-fold through a multi-step procedure which included affinity chromatography using NAD⁺ -Agarose. Three forms of the enzyme were separated by gel-filtration but only the major form was purified. The pH optimum of the enzyme was 9.5. Exogenous NAD⁺ was not required for enzymic activity but its removal caused inactivation. The enzyme was unstable below pH 7.0 but stable at pH 8.0 in the presence of glycerol and at ?20° for two months. The equilibrium constant for the enzyme-catalysed reaction was 3.2 ± 0.15. The K_m for UDP-galactose and UDP-glucose were 0.12 mM and 0.25 mM, respectively. The inhibition by NADH was competitive, with a K_i of 5 μM. The MW of the enzyme was 78 000; the two minor forms showed the values of 158 000 and 39 000, respectively.