不同干扰条件下枸杞园节肢动物群落结构与动态

2008年通过对宁夏银川地区不同干扰条件下枸杞园节肢动物群落的系统调查,共采集节肢动物151628头,鉴定出4纲27目76科167种,其中天敌亚群落61种,化防园23种,有机园30种,自生园61种,天敌总量的比例分别为10.87%、18.78%、70.34%。通过群落结构分析,自生园丰富度、个体数均明显高于化防园和有机园,有机园均匀度、多样性较高,而化防园丰富度、个体数指数都较低,而优势集中度高。通过主分量分析表明潜叶类害虫与刺吸类害虫是不同人工干扰条件下的主要害虫,刺吸类害虫成为发展有机枸杞的重要障碍,食花果类害虫具有较大的危害潜力;寄生类天敌、病原类天敌为自生园优势天敌,捕食类天敌是有机园、化防园的优势天敌,但化防园天敌作用较为微弱。自生园天敌亚群落与害虫亚群落第一对典型变量为V1=0.048x1-0.2533x2+0.5951x3+0.5207x4,W1=0.9021y1+0.0354y2+0.0223y3+0.1847y4-0.0591y5,相关系数为0.8635,化防园、有机园天敌亚群落与害虫亚群落第一对典型变量的相关系数分别为0.6826、0.7332。通过害虫-天敌亚群落的种群消长动态表明,天敌亚群落作为整体对害虫发挥着调控作用,自生园7-9月份寄生性天敌对刺吸式害虫的跟随作用很强,有机园较弱,化防园则不明显。     

水土保持型牧草苇状羊茅(Festuca arundinacea Schreb)节肢动物群落结构

对水土保持型牧草苇状羊茅节肢动物群落的系统调查,根据节肢动物群落中物种的营养和取食关系将总群落划分为天敌亚群落和非天敌亚群落(含害虫和中性昆虫),以调查到的节肢动物种类、个体数量结合各群落生态学指标分析总群落及亚群落的结构组成.结果表明:共查得苇状羊茅节肢动物139种分属68科;非天敌亚群落为总群落主要成分,相对多度为0.7661,其中优势种为同翅目昆虫;天敌亚群落相对多度为0.2339;优势种为蜘蛛类天敌.优势集中性和优势度分析表明非天敌亚群落>总群落>天敌亚群落;均匀度指数除5、9月份外,均表现为天敌亚群落>总群落>非天敌亚群落;多样性指数除4、5月份外,均表现为总群落>非天敌亚群落>天敌亚群落.     

稻田节肢动物群落多样性

本文运用种类丰富度(S)、均匀性(V)和申农指数(Shannon's index.H')分析稻田节肢动物群落和各亚群落多样性的空间层次差异、季节动态、以及杀虫药剂的作用.稻田节肢动物群落的多样性值较低,H'值一般在3以下,表明群落稳定性差;多样性季节变化较大.在不用农药条件下,8月底以后的H'值较高;水稻群体上部群落的S、和V'值均大于下部的对应值;杀虫药剂的应用虽提高了群落总体的H'和V'值,但对亚群落的分析表明,杀虫药剂促进害虫亚群落的H'和V'值上升,却降低了各天敌亚群落的有关值,从而扩大了害虫和天敌之间稳定性的差距,使两者的同步关系受到损害;杀虫药剂的应用还使各天敌亚群落种类数和个体数明显减少,特别是寄生天敌昆虫种类数、个体数均大幅度下降,使其难以起到控制害虫的应有作用,这又为害虫的再猖獗提供有利条件.通过分析认为,就稻田节肢动物而言,多样性仍然是群落稳定性的一个重要测定指标.     

蚜虱净对苜蓿田节肢动物群落结构及动态的影响

以物种丰富度(S)、个体数量(N)、香农指数(Shannon’sindex,H′)和均匀度指数(E)作为多样性指标,研究了蚜虱净对苜蓿田节肢动物群落结构和季节动态的影响.结果表明:蚜虱净对天敌亚群落物种数的影响大于害虫亚群落,使总群落和害虫亚群落的优势集中性显著增加,但5月底施药对传粉蜜蜂类亚群落的优势集中性无显著影响.喷药初期,蚜虱净显著降低了蚜虫、蓟马等害虫数量,7d后蚜虫、蓟马等种群数量迅速回升,40d后超过对照;施药初期天敌亚群落的物种数大幅减少,多样性和均匀度指数较低,7d后天敌的物种数逐渐回升,到后期与对照田基本一致,但个体数量一直未恢复至对照水平.     

不同作物布局方式对转基因抗虫棉田节肢动物群落结构的影响

比较了不同作物布局下转基因抗虫棉田节肢动物的群落结构.结果表明,与单作棉田相比,蔬菜-棉花、果树-棉花及花生-棉花布局的棉田节肢动物群落、植食性害虫亚群落和天敌亚群落的物种数均增加,中性节肢动物的数量均有增加;蔬菜-棉花和花生-棉花布局的棉田植食性害虫个体数量增加;蔬菜-棉花和果树-棉花布局的棉田天敌个体数量增加.花生-棉花和果树-棉花布局棉田的节肢动物群落相似性最大;而单作棉田与蔬菜-棉花布局棉田的节肢动物群落相似性最小.R啨nyi多样性指数表明,与单作棉田相比,蔬菜-棉花布局棉田节肢动物群落多样性较低,害虫亚群落多样性较低;果树-棉花布局棉田节肢动物群落多样性较高,天敌亚群落多样性较高;花生-棉花布局棉田节肢动物群落多样性较高,害虫亚群落多样性较高.果树-棉花布局是值得推广的转基因抗虫棉田布局方式.     

抗虫转基因水稻和化学杀虫剂对稻田节肢动物群落的影响

从功能团优势度、功能团内科组成及其优势度、功能团个体数量、群落主要参数及群落结构相异性等方面,就含crylAb／crylAc融合基因的Bt水稻和化学杀虫剂对稻田节肢动物群落影响进行比较研究．结果表明,与对照田相比,Bt稻田的节肢动物功能团组成及其优势度、各功能团内科组成及其优势度分布、功能团内个体数量的时间动态、群落参数(物种丰富度、Shannon-Wiener多样性指数、均匀性指数、优势集中性指数)及时间动态在大多情况下均无显著差异,两者间群落结构相似性较高．Bt水稻对稻田节肢动物群落基本无明显的负效应、而化防田的功能团优势度等群落特征指标与对照田相比,有时具有明显甚至显著的差异;群落结构相似性也较低．综合分析表明,Bt水稻对稻田节肢动物群落的影响明显弱于化学杀虫剂。     

梨园芳香植物间作区节肢动物群落时序格局

以沙地梨园间作罗勒、孔雀草、薄荷为处理,自然生草和清耕区为对照,应用最优分割法和模糊聚类法,探讨梨园节肢动物群落、害虫亚群落和天敌亚群落发生的时序格局特征及其相互联系。结果表明:总群落、害虫亚群落以及其优势种个体数时序变化趋势呈偏态分布,而天敌亚群落以及其优势种个体数的呈正态分布,高峰期出现在6月末至7月中旬,比总群落和害虫亚群落个体数发生高峰晚。在梨树年生长周期的主要时段中,芳香植物间作区较自然生草区、清耕区害虫亚群落的发生数量(4月中至8月底)少;而天敌亚群落发生数量(4月底至6月底)多。梨园各间作区节肢动物总群落和害虫亚群落时序最优格局均可划分5个时段:发展初期、发展期、稳定期、波动期和衰退期;天敌亚群落分为3个时段:发展期、稳定期、衰退期。但处理间在发生时段的时间范围、发生数量及组成特征上存在复杂的差异。梨园节肢动物总群落、害虫亚群落、天敌亚群落时序聚类结果不同,预示着处理间节肢动物总群落、害虫亚群落和天敌亚群落在各发生时段上的个体组成、物种丰富度、群落多样性指数、优势度和均匀度指数存在着差异。     

吡虫啉对烟田节肢动物群落的影响研究

利用群落参数分析了吡虫啉对烟田节肢动物群落及其各亚群落的影响。结果表明,施药后对烟田节肢动物群落、害虫亚群落的物种数有一定的影响,对天敌昆虫和蜘蛛亚群落物种数的影响不明显。5月23日施药后至6月13日施药区(Ⅱ)和对照区节肢动物群落、害虫亚群落个体数均下降,下降程度施药区大于对照区。6月14日施药后施药区节肢动物群落、害虫亚群落个体数下降,对照区显著上升。两次施药对天敌昆虫和蜘蛛亚群落个体数的影响不明显,施药后一段时间内优势种烟蚜种群个体数量显著下降,使节肢动物群落和害虫亚群落优势集中性下降,多样性指数和稳定性增加。     

大豆田节肢动物群落优势种群时间生态位及营养关系分析

【目的】阐明大豆田节肢动物群落时间生态位及营养关系,为大豆害虫生态调控手段的实施提供坚实的理论依据。【方法】以大豆田节肢动物群落为研究对象,通过两年的田间系统调查分析。【结果】统计得到种类220余种,物种可分为天敌、害虫和中性昆虫3个类群,以天敌物种丰富度最高;害虫中以烟蓟马Thrips tabaci(0.36902)和大豆蚜Aphis glycines(0.13122)优势度最高,且有着较高的生态位重叠指数(0.8163),蚜小蜂Aphytis sp.和大草蛉Chrysopa septempunctata对害虫的时间生态位重叠指数很高,其他天敌如异色瓢虫Harmonia axyridis、龟纹瓢虫Propylaea japonica、黑带食蚜蝇Zyistrophe balteata和黑食蚜盲蝽Deraeocoris punctulatus等对害虫的重叠指数居中;大豆田中各类群构成错综复杂的食物网结构。【结论】综合考虑天敌的种群数量,确定捕食性天敌是控制害虫种群数量的有效天敌。研究可知不能单纯从时间生态位的重叠指数的高低来判断天敌的控制能力。     

不同抗性品种稻田捕食性节肢动物的群落结构

对3个类型稻田早、晚稻捕食性节肢动物群落调查,结果表明:共有捕食性节肢动物67种,丰富度以蜘蛛高于捕食性昆虫类;早稻高于晚稻;中抗品种高于抗虫和感虫品种。早稻以皿蛛科Linyphiidae的食虫沟瘤蛛UlmmeliatainsecticepesBoes.etStr.占优势,晚稻则以狼蛛科Lycosidae的相对丰盛度最高。早稻捕食性天敌数量动态以中抗品种峰期最长;感性样田中天敌平均密度与中抗样田差异不显著,与抗虫品种差异显著;捕食性节肢动物多样性随着品种抗性的增强呈降低趋势,优势度随着品种抗性的增强而增强。晚稻3个品种样田中天敌的平均密度差异不显著;各品种样田的多样性明显高于早稻,且波动幅度小于早稻,品种之间多样性差异较小,晚稻群落可能具有较高的稳定性。     

Weed communities of rain-fed lowland rice vary with infestation by Rhamphicarpa fistulosa

The facultative hemiparasitic plant Rhamphicarpa fistulosa (Orobanchaceae) thrives in seasonally wet soils in sub-Saharan Africa, mainly in marginal lowland rice growing environments where weeds are already a major constraint for rice production. Because lowland rice production is increasing in tropical Africa, it is important to ascertain the influence of R. fistulosa on weed plant communities in these rice-growing habitats. We investigated weed plant community richness and composition at four different levels of R. fistulosa infestation across two years of surveys from lowland rice fields in northern Togo (West Africa). Despite a lack of significant differences in community richness among sites with different R. fistulosa infestation levels, there were significant differences in community composition, both when estimated from presence-absence data and from relative abundance data, after controlling statistically for geographic proximity among sites. Rhamphicarpa fistulosa infestation, therefore, may influence the competitive balance between rice and its weeds and shape weed community structure. However, experimental studies are required to elucidate the weed host range of R. fistulosa and the direct and indirect effects of this hemiparasite in rice fields in order to predict its net impact on rice and its weed species.     

水稻害虫治理措施的综合评价

在对广州有机水稻生产示范区稻田节肢动物多样性和害虫控制效果调查分析的基础上,应用层次分析法对研究区有机水稻生产过程中经济、社会和生态3方面的效益和代价进行了评价.结果表明：有机水稻生产方式下所产生的综合效益最大,权重值达0.5355;生态代价在综合代价中占据主导地位;化学防治病虫害的水稻生产方式付出的生态代价最惨重,其综合代价权重值达0.6252;从综合效益代价比（RPC）来看,有机水稻生产模式是较理想的模式,其RPC值达2.4776,符合农业可持续发展的要求.     

Gene identification using rice genome sequences

Identifying useful gene(s) is one of the most important objectives of plant geneticists. Various strategies can be used, which are based on the characteristics of plant reproduction and available technology. Rice is the first model crop whose whole genome sequence has been reported. In addition, information on the whole genome sequences of two important rice subspecies (japonica and indica rice) is also available. Rice is a self-pollinating crop and methods of artificial crossing are relatively easy to perform; such methods enable the production of numerous seeds for genetic analyses. Based on these features, a map-based cloning (i.e., positional cloning) strategy has been successfully applied over the last decade to identify rice genes. Recently, advanced next-generation sequencing (NGS) technology was used to ascertain the genome sequences of individual plants, opening up a new strategy for gene identification. This strategy has been used successfully to identify the genes responsible for certain qualitative traits in rice. However, to identify the gene(s) involved in a quantitative trait, a map-based cloning strategy is still required after quantitative trait loci analysis using NGS technology. In this review, we discuss both map-based cloning (which is still the primary strategy used to identify rice genes) and NGS-based strategies.     

水稻广谱抗稻瘟病基因研究进展

稻瘟病是水稻生产中的最严重病害之一,由于稻瘟菌小种的高度变异性,垂直抗性基因难以持续控制稻瘟病的危害,因此,克隆和利用广谱持久抗瘟基因被认为是解决稻瘟病问题最经济有效的策略。本文从广谱抗源的筛选与利用,广谱抗瘟基因的定位、克隆与应用等方面对水稻广谱抗稻瘟病基因研究取得的进展进行了概述,并介绍了广谱抗性分子机理的最新研究进展。基于国内外稻瘟病抗性基因研究的现状及趋势,以及我国丰富的抗瘟水稻种质资源,克隆越来越多的广谱抗瘟基因具有重要的理论与应用价值。     

Strategy and utilization of a herbicide resistance gene in two-line hybrid rice

Hybrid rice plays an important role in China's aim to improve rice production as it accounts for some 50% of rice planting area but produces about 60% of the total rice grain. However, the existing three-line system used in hybrid rice production has its limitations. The two-line system, which makes use of photoperiod-sensitive genic male-sterile (PGMS) and thermo-sensitive genic male-sterile (TGMS) lines to generate the male-sterile parental line, was developed to overcome some of these limitations. The sterility of the male-sterile line of two-line hybrid rice, however, fluctuates when the temperature-sensitive phase of fertility encounters abnormal low temperatures during hybrid seed production, which induces selfing and decreases the purity of hybrid. We describe here the strategy of utilizing a herbicide resistance gene in two-line hybrid rice to eliminate this fluctuation in the sterility of the P/TGMS lines during hybrid seed production and reports the development of the herbicide resistance restorer line Bar68-1 and its herbicide-resistant early season hybrid rice Xiang125s/Bar68-1. When the restorer line and its derived hybrid are herbicide resistant, the selfed seeds can be removed easily from the hybrid by herbicide spraying. A herbicide resistance gene bar was transferred into a restorer line by particle bombardment. The resulting transgenic restorer line Bar68-1 and its hybrid Xiang125 s/Bar68-1 inherited stable herbicide resistance. The purity of Xiang125s/Bar68-1 was increased by spraying the seed bed with herbicide, which resulted in a significant increase in yield, grain quality, and disease resistance in comparison to the controls in a regional trial.     

Response and relation of allantoin production in different rice cultivars to competing barnyardgrass

The production of secondary metabolites and biomass of plants may be altered by coexistence and competition. Rice has coexisted with barnyardgrass in paddy systems for centuries and represents a model system for understanding plant–plant interactions. Despite increasing knowledge of allelochemicals produced and released by rice involved in coexistence of these two species, relatively little is known about the role and production of beneficial chemicals of rice in response to competing barnyardgrass. The purpose of this study was to quantify the growth-stimulating allantoin (5-ureidohydantoin) and its effect on barnyardgrass growth in a rice–barnyardgrass system. In this system, rice produced and released allantoin but barnyardgrass did not. The production of allantoin by rice responded to competition from barnyardgrass, and its concentration varied among rice cultivars tested. At 1:1 barnyardgrass and rice mixture proportion, allantoin concentration in allelopathic cultivars was obviously lowered by competing barnyardgrass, while no significant variation of allantoin concentration was observed in non-allelopathic cultivars. Barnyardgrass biomass was reduced in mixed-culture with rice cultivars, in particular, allelopathic cultivars. There was a positive relationship between allantoin concentration in rice cultivars and barnyardgrass biomass. Furthermore, allantoin stimulated the growth of barnyardgrass once released from rice or added to soil. The results suggest that rice plants of allelopathic cultivars appear to be able to detect the presence of competing barnyardgrass and respond by decreasing production of growth-stimulating allantoin, regulating the growth of barnyardgrass. In this manner, given rice cultivars may alleviate the competition of barnyardgrass and provide greater benefit to their own growth.     

水稻种子的细菌含量和群落结构及其影响因素分析

【目的】种子是植物微生物群代际传递的重要途径，但种子携带的微生物群落尚缺乏系统的研究。本研究以水稻种子为模型，定量分析种子的细菌含量、测定种子的细菌群落结构、探究地域与品种对细菌含量及群落结构的影响和鉴定水稻种子的核心菌群。【方法】选取18个水稻品种，每个品种分别来自中国海南和天津2个地域，共36组样本。每组样本包含5或10个DNA样本，每个DNA样本由3粒种子提取的总DNA构成。使用细菌特异性16S rDNA介导的荧光定量PCR技术测定种子的细菌含量，并分析影响因素；使用16S rDNA扩增子测序技术测定种子的细菌群落结构，并用生物信息学方法分析了影响因素和核心菌群。【结果】本研究测定了1 080粒水稻种子的细菌含量，发现经过表面除菌的水稻种子内部存在共栖细菌，平均每克种子的细菌含量为1.53×10⁶。水稻品种对种子的细菌含量有显著影响，而地域无影响。测定180个扩增子文库的细菌群落结构，发现水稻种子的菌群与水稻植株有相似之处，均以变形菌门为主要的细菌门类；地域对水稻种子的细菌群落结构有重要影响，不同地域的水稻种子在主坐标分析(principal co-ordinate analysis, PCoA)中有明显分离；而粳稻和籼稻之间无显著差异。还发现水稻种子存在核心菌群，且相对丰度高达总菌群的85.56%。【结论】本研究系统地揭示了水稻种子的细菌含量、群落结构及其影响因素，为利用种传微生物促进水稻健康提供了数据和方法支持。     

Genetic variation in biomass traits among 20 diverse rice varieties

Biofuels provide a promising route of producing energy while reducing reliance on petroleum. Developing sustainable liquid fuel production from cellulosic feedstock is a major challenge and will require significant breeding efforts to maximize plant biomass production. Our approach to elucidating genes and genetic pathways that can be targeted for improving biomass production is to exploit the combination of genomic tools and genetic diversity in rice (Oryza sativa). In this study, we analyzed a diverse set of 20 recently resequenced rice varieties for variation in biomass traits at several different developmental stages. The traits included plant size and architecture, aboveground biomass, and underlying physiological processes. We found significant genetic variation among the 20 lines in all morphological and physiological traits. Although heritability estimates were significant for all traits, heritabilities were higher in traits relating to plant size and architecture than for physiological traits. Trait variation was largely explained by variety and breeding history (advanced versus landrace) but not by varietal groupings (indica, japonica, and aus). In the context of cellulosic biofuels development, cell wall composition varied significantly among varieties. Surprisingly, photosynthetic rates among the varieties were inversely correlated with biomass accumulation. Examining these data in an evolutionary context reveals that rice varieties have achieved high biomass production via independent developmental and physiological pathways, suggesting that there are multiple targets for biomass improvement. Future efforts to identify loci and networks underlying this functional variation will facilitate the improvement of biomass traits in other grasses being developed as energy crops.     

Induced tyramine overproduction in transgenic rice plants expressing a rice tyrosine decarboxylase under the control of methanol-inducible rice tryptophan decarboxylase promoter

Tyramine, one of the various biogenic amines found in plants, is derived from the aromatic L-amino acid tyrosine through the catalytic reaction of tyrosine decarboxylase (TYDC). Tyramine overproduction by constitutive expression of TYDC in rice plants leads to stunted growth, but an increased number of tillers. To regulate tyramine production in rice plants, we expressed TYDC under the control of a methanol-inducible plant tryptophan decarboxylase (TDC) promoter and generated transgenic T(2) homozygous rice plants. The transgenic rice plants showed normal growth phenotypes with slightly increased levels of tyramine in seeds relative to wild type. Upon treatment with 1% methanol, the transgenic rice leaves produced large amounts of tyramine, whereas no increase in tyramine production was observed in wild-type plants. The methanol-induced accumulation of tyramine in the transgenic rice leaves was inversely correlated with the tyrosine level. These data indicate that tyramine production in rice plants can be artificially controlled using the methanol-inducible TDC promoter, suggesting that this promoter could be used to selectively induce the expression of other proteins or metabolites in rice plants.