植物提取物对大豆疫霉菌抗菌活性的初步研究

采用Paper Disk法测定了云南省200种植物的提取物对大豆疫霉(Phytophthora sojae)的抑菌活性。结果表明,光叶合欢(Albizia lucidior)、白钩藤(Uncaria sessilifructus)及黄豆树(Albizia procera)的提取物在浓度为10μg/μL时有较好的抗菌活性,而在2.5μg/μL时只有黄豆树提取物显示出抗菌活性。并从黄豆树中分离出其抗菌的主要活性成分3-O-[α-L-arabinopyranosyl-(1→2)-β-D-fucopyranosyl-(1→6)-2-acetamidO-2-deoxy-β-D-glu-copyranosyl]echinocystic acid。     

Effect of Weed on the Sexual Indices of Spiders (Araneae) in Transgenic Sugar Beet and Maize Fields

In the years 1997 and 1998 effects of weed on the sexual indices of spiders (Araneae) were carried out during field tests with transgenic, herbicide tolerant sugar beet and maize crops. Because of the tolerance of the plants and the possible late application, different weed cover was determined in treatments. Catching was done with pitfall traps. Conventional fields of the same crops were used with a minimum distance of 500m from the testing site. With exception of O. apicatus (Blackwall) the catching of the males were higher than that of the females and the juveniles. No indirect effects of weed couldn't be determined on the species with exception of P. microphthalmum (O.P.-Cambridge) in both cultures maize and sugar beet.     

Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants)

Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production.     

Na+ transport in plants

The ability of plants to grow in high NaCl concentrations is associated with the ability of the plants to transport, compartmentalize, extrude, and mobilize Na(+) ions. While the influx and efflux at the roots establish the steady state rate of entry of Na(+) into the plant, the compartmentation of Na(+) into the cell vacuoles and the radial transport of Na(+) to the stele and its loading into the xylem establish the homeostatic control of Na(+) in the cytosol of the root cells. Removal of Na(+) from the transpirational stream, its distribution within the plant and its progressive accumulation in the leaf vacuoles, will determine the ability to deal with the toxic effects of Na(+). The aim of this review is to highlight and discuss the recent progress in understanding of Na(+) transport in plants.     

Montane Refugia for Endemic and Red Listed Dragonflies in the Cape Floristic Region Biodiversity Hotspot

One of the features of many endemic organisms is that they are highly spatially restricted, and habitat specialists. The Kogelberg Biosphere Reserve (KBR) is a major centre of plant endemism within a global hotspot, the Cape Floristic Region (CFR). Dragonflies in this botanical hotspot have a range of habitat specialization from narrow-range specialists to widespread generalists, with an unusually strong bias towards the specialists. A huge 53% of dragonfly individuals and 26% of taxa recorded are national endemics, and three species are Red Listed. Thus, a group of predatory insects, which are largely not dependent on plant composition, mirrors the level of habitat specialization and restricted distributions of the plants at the spatial scale of the whole reserve. Although some studies caution the use of one taxon as a surrogate for another, the results here show that at the reserve scale in this global hotspot there can be remarkable concordance, suggesting further studies on other taxa should be carried out to determine the full extent of taxonomic concordance in this irreplaceable area.     

中国极小种群野生植物保护理论与实践研究进展

极小种群野生植物大都分布范围狭窄、个体数量稀少且自然更新困难, 面临随时灭绝的风险, 迫切需要拯救性保护。极小种群野生植物这一概念自提出以来受到了保护生物学领域的广泛关注, 已成为当前中国生物多样性保护的一个热点方向。我国于2010年正式启动实施极小种群野生植物拯救保护工程, 并开展了大量的保护研究和实践。以“extremely small population*”和“plant”为检索词在Web of Science进行了主题检索, 以“极小种群”和“植物”为检索词在中国知网进行了主题检索, 对获取的的学术期刊论文、学位论文和会议论文进行了梳理。本文从极小种群野生植物种群、群落及生境调查与监测、适应性、遗传多样性、繁殖生物学、濒危机制、动态模型6个方面对近年来极小种群野生植物的理论研究工作进行了较为系统的综述。在此基础上, 从就地保护、迁地保护与种质资源保存、野外回归、人工繁育、标准化体系5个方面回顾了极小种群野生植物保护实践及取得的进展。基于极小种群野生植物保护理论与实践研究现状, 我们建议在极小种群野生植物未来保护工作中不断调整和完善保护名录, 加强种群结构的观测和预测、小种群形成和恢复机制的针对性研究以及特定物种的长期系统性研究, 同时促进这一概念在国际上的推广。希望本文能为国家生物多样性保护和生态文明建设提供参考。     

Evaluation of cocksfoot (Dactylis glomerata L.) population for drought survival and behavior

Climate change models predict frequent and intense droughts in the world. Development of drought-tolerant species and cultivars is necessary to cope with such changes. Forage grass species are affected, especially in the Mediterranean region. The aim of the present study was to investigate the diversity for drought survival, summer dormancy, and productivity within a cocksfoot population.The study was conducted in Morocco, under field conditions from 2011 to 2013. 283 genotypes of cocksfoot and parents were tested, characterized for dry matter yield, heading date, plant height, senescence, summer dormancy, and drought survival. Results exhibited a large variability between traits. 79% of the population had survived after severe drought summer while 57% yielded more than both parents. Also, 63% of the progeny had an intermediate score of summer dormancy estimated by senescence score. Large variability was also noticed for heading date and plant height. Several accessions combined a high yield and persistence under severe summer drought. Which explain the significant correlation (r = 0.18, P < 0.005) founded between total dry matter accumulated in 2013 and plant survival. Accordingly, our results showed that we can rise persistent and resilient genotypes among population with a good level of biomass.     

A comparison of performance of plant miRNA target prediction tools and the characterization of features for genome-wide target prediction

Background

Deep-sequencing has enabled the identification of large numbers of miRNAs and siRNAs, making the high-throughput target identification a main limiting factor in defining their function. In plants, several tools have been developed to predict targets, majority of them being trained on Arabidopsis datasets. An extensive and systematic evaluation has not been made for their suitability for predicting targets in species other than Arabidopsis. Nor, these have not been evaluated for their suitability for high-throughput target prediction at genome level.

Results

We evaluated the performance of 11 computational tools in identifying genome-wide targets in Arabidopsis and other plants with procedures that optimized score-cutoffs for estimating targets. Targetfinder was most efficient [89% ‘precision’ (accuracy of prediction), 97% ‘recall’ (sensitivity)] in predicting ‘true-positive’ targets in Arabidopsis miRNA-mRNA interactions. In contrast, only 46% of true positive interactions from non-Arabidopsis species were detected, indicating low ‘recall’ values. Score optimizations increased the ‘recall’ to only 70% (corresponding ‘precision’: 65%) for datasets of true miRNA-mRNA interactions in species other than Arabidopsis. Combining the results of Targetfinder and psRNATarget delivers high true positive coverage, whereas the intersection of psRNATarget and Tapirhybrid outputs deliver highly ‘precise’ predictions. The large number of ‘false negative’ predictions delivered from non-Arabidopsis datasets by all the available tools indicate the diversity in miRNAs-mRNA interaction features between Arabidopsis and other species. A subset of miRNA-mRNA interactions differed significantly for features in seed regions as well as the total number of matches/mismatches.

Conclusion

Although, many plant miRNA target prediction tools may be optimized to predict targets with high specificity in Arabidopsis, such optimized thresholds may not be suitable for many targets in non-Arabidopsis species. More importantly, non-conventional features of miRNA-mRNA interaction may exist in plants indicating alternate mode of miRNA target recognition. Incorporation of these divergent features would enable next-generation of algorithms to better identify target interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-348) contains supplementary material, which is available to authorized users.     

植物多基因转化研究进展

通过转基因技术改良植物品质近几年已成为热点研究问题,基因工程不断发展,单基因转化技术已不能满足人们对植物改良的需要。更多的研究者投身于参与某个代谢途径的多个基因在植物体中共同表达的研究,通过多基因调控来获得更好的植物性状。基因的协调表达有四种研究思路,在此基础上多基因转化方法可概述为传统转化法、改进后的共转化法,及新兴的基因融合方法,综合分析每种方法在植物代谢调控中的优缺点与应用,并探讨多基因整合的不稳定及相互作用问题。     

Where are threatened ferns found? Global conservation priorities for pteridophytes

Recent efforts to improve the representation of plant species included on the IUCN Red List of Threatened Species through the IUCN Sampled Red List Index (SRLI) for Plants have led to the assessment of almost 1000 additional species of pteridophytes and lycophytes under IUCN Red List criteria. Species were selected at random from all lineages of pteridophytes and lycophytes and are taxonomically as well as ecologically representative of pteridophyte and lycophyte diversity. 16% of pteridophyte and lycophyte species are globally threatened with extinction and 22% are of elevated conservation concern (threatened or Near Threatened); of species of pteridophytes and lycophytes previously included on the Red List, 54% were considered threatened. Over half of pteridophyte and lycophyte species assessed for the SRLI use estimates of range size; therefore the method used to measure range may affect the Red List category assigned. We evaluated this using two alternative metrics for estimating range, species distribution modelling (SDM) and ecologically suitable habitat (ESH), for 227 species endemic to the Neotropical biogeographic realm. Differences between range estimates were small when ranges were small but increased with increasing range size. For 58 (25.6%) species alternative modelling techniques result in the species meeting the threshold for a different IUCN Red List category from using extent of occurrence. Modelling threatened species distributions also highlights priority areas for conservation in tropical and subtropical montane forests that are the most species-rich habitat for small-range pteridophyte and lycophyte species, but which are now increasingly subject to rapid conversion to agriculture.