土壤-植物-大气连续体系中氮的研究进展

氮素是植物最需要的重要养分元素之一.近年来,土壤-植物-大气这一连续体系(SPAC)中的氮循环成为研究的热点之一.大气中的氮素可以通过生物固定和N沉降等作用进入土壤和植物内,同时土壤和植物内的氮素又会以氨挥发和氮氧化物等方式排放到大气中.氮素通过生物固持和植物吸收等方式进入植物体内,植物器官脱落使植物损失一部分的氮素,另外雨水的淋洗和植物溢出液也会造成植物的N损失.植物氮素在植物体内的积累和分布随着生长时期和各营养器官而有所不同.另外,植物吸收氮素的过程又受到大气状况和土壤状况的制约.土壤中氮素经过矿化作用、硝化作用和反硝化作用进行转化,一部分把氮素转化成植物能吸收的营养形态,另一部分则从土壤中损失.凋落物的分解和N沉降能补充土壤中的氮素,而植物吸收、微生物固持、水文流失和N溢出等方式使氮素从土壤中损失出去.另外,凋落物的分解和根际土壤、CO2浓度和臭氧对氮素循环有着重要的作用.N污染、N沉降、碳氮循环的耦合作用是今后研究的热点问题.     

植物3-羟基-3-甲基戊二酰辅酶A还原酶基因研究进展

细胞分裂素、赤霉素、脱落酸、叶绿素、萜类等类异戊二烯物质,是植物中广泛存在的一类代谢产物,在植物生长发育过程中起着非常重要的作用。一些萜类化合物作为药物的合成前体或有效的药用成分在工农业及医药生产上具有重要的经济价值。类异戊二烯物质主要通过甲羟戊酸代谢途径中的一系列酶催化合成,其中,3-羟基-3-甲基戊二酰辅酶A还原酶(3-hydroxy-3-methylglutaryl coenzyme A reductase, HMGR)是该代谢途径中的第一个关键限速酶,能够将3-羟基-3-甲基戊二酰辅酶A转化成中间代谢产物甲羟戊酸。对植物HMGR基因的克隆、酶结构和功能分析、基因组织表达及调控等方面进行了综述,旨在为其在重要农作物的遗传改良、代谢产物工程植物创制以及植物亲缘关系分析中的应用等研究提供理论依据。     

植物-微生物联合修复化学农药污染土壤的研究进展

化学农药的高毒性、生物积累性和扩散性极易对环境及人类健康造成危害,环境中化学农药的去除尤为重要。植物-微生物联合修复技术因其高效、环境友好和修复成本低等优点受到越来越多的关注,植物-微生物联合修复化学农药污染土壤是一种很有前景的方法。植物为根际和内生细菌提供养分,而细菌通过化学农药的降解和解毒来支持植物生长。本文综述了影响化学农药在植物体内吸收和转运的因素以及植物-微生物修复技术的原理,并讨论了植物与微生物在化学农药污染土壤修复中的协同效应,并对植物-微生物联合修复法在化学农药污染土壤修复中的应用前景进行了展望。     

植物体内的2,6-二磷酸果糖调控系统

文章论述了Fru-2,6-P_2调控系统在植物细胞中的分布、定位、催化特性及其相互作用。阐述了Fru-2,6-P_2系统在植物糖酵解中的调节作用及其可能机理,重点讨论:Fru-2,6-P_2系统在植物光合碳代谢中的重要调节作用,并简要探讨Fru-2,6-P_2作为一种新的信号物质,在植物逆境生理中的可能作用。     

高等植物赤霉素3-β-双氧化酶基因研究进展

赤霉素3-β-双氧化酶(GA3ox)是赤霉素(GA)生物合成过程中的关键酶之一,直接作用于活性GA的生成,在植物的生长发育过程中发挥着重要作用。GA3ox已在拟南芥、烟草、高粱和杨树等多种植物中得到克隆,在植物个体的不同生长阶段、不同组织中GA3ox的表达量均存在着差异,这主要是由物种内在的遗传因素所决定的,同时环境因子和外源激素处理对GA3ox表达也有着显著的影响。通过对基因突变体的研究,揭示出GA3ox突变导致GA的生物合成受阻而间接影响植物的生长,导致植物茎秆、花、种子、果、根等部位性状的改变,包括植株矮化、结籽困难等。过量表达GA3ox基因促进GA的生成,诱导细胞的分裂与分化,促进根尖的径向伸长、种子萌发等。主要从GA3ox的基因克隆与表达模式及其功能效应两方面综述了其在高等植物中研究进展,通过对GA3ox在不同植物中的相关功能研究,探讨其在植物生长发育过程中的具体作用,以期为了解GA3ox对植物生长发育的调控机制提供参考,也有助于在生产实践中更好地利用GA3ox开展基因工程研究,定向培育植物新品种。     

内切-1,4-β-葡聚糖酶在植物细胞生长发育中的作用

内切-1,4-β-葡聚糖酶(EGases)可以催化水解具有1,4-β-葡聚糖主链的多聚糖,如纤维素和木葡聚糖分子,从而参与对细胞壁的修饰.植物细胞中存在一个EGase蛋白家族,且多为分泌蛋白;在植物细胞中还存在另一类跨膜EGase,是细胞壁纤维素生物合成所必需的,但植物EGases在体外具有降解纤维素人造底物羧甲基纤维素(CMC)的能力,而绝大多数植物EGases在活体细胞中并不能有效地降解结晶态纤维素分子和木葡聚糖分子.本文就EGases在细胞伸长、果实成熟和组织器官脱落等发育过程中的作用,以及EGases在植物纤维素合成与降解中的作用进行综述.     

反式-2-己烯醛在植物防御反应中的作用

反式-2-己烯醛是绿色植物释放的一种小分子挥发性物质,在调节植物生长发育和抵抗各种环境胁迫中发挥重要作用。已有研究表明,反式-2-己烯醛可抑制植物根系生长,具有较高的抑菌和抗虫活性,也可以作为植物间的“信使”来传递防御信号。该文系统综述了反式-2-己烯醛的生物合成、代谢途径及其在生物胁迫防御反应中的重要作用,提出了研究...     

植物黄烷酮-3-羟化酶基因研究进展

黄烷酮3-羟化酶(flavanone 3-hydroxylase,F3H)作为植物进入不同类黄酮代谢物分支的一个中枢酶,可以催化生成花青素和黄酮醇合成的共同前体物质二氢黄酮醇,在类黄酮合成途径中起着十分重要的调控作用。本文从F3H基因的发现、结构功能和表达调控等方面,综述了F3H基因在调节植物花青素和黄酮醇合成中的研究进展及调控网络,并对未来研究方向进行了展望。期望为F3H基因在植物类黄酮代谢合成途径的调控机制研究提供参考,也有助于利用F3H开展基因工程研究,定向培育植物新种质。     

核磁共振技术在土壤-植物-大气连续体研究中的应用

植物体内的水分状态与传输过程是土壤-植物-大气连续体(SPAC)水分传输理论的核心内容,也是研究植物水分利用与调控的基础.植物体内水分的传输过程受外界环境影响较大,植物需要通过对体内水分状态的适当调整来适应环境变化和维持自身的生长发育.由于蒸发通量、压力室、高压流速仪、热脉冲等传统检测方法往往会对植株造成破坏和损伤,因此难以准确反映和定量描述植物体内水分传输的真实过程.核磁共振技术(NMR)由于其无损、非侵入的特点,在植物水分分布和传输相关研究中日益得到关注.本文概述了NMR在检测植物体内水分分布、传输以及含量测定等方面的研究进展,还分析了目前NMR技术在SPAC系统研究中存在的问题及可能的解决方法,并指出NMR技术将来可能在植物水分生理、植物与环境互作以及水分代谢等相关研究领域的应用.NMR技术在SPAC系统研究中的应用在我国仍处于初级阶段,开发户外便携式、开放式检测仪器是NMR技术在SPAC研究领域进一步应用和推广的关键所在.     

[反]-β-法尼烯合成酶基因在植物抗蚜分子育种中的应用

蚜虫是重要的农业害虫,每年造成数以亿计的经济损失。[反]-β-法尼烯[(E)-β-farnesene,EβF]是绝大多数蚜虫报警信息素的主要成分,可使蚜虫产生骚动、从植株上脱落,并吸引蚜虫天敌,有效控制蚜虫危害。EβF合成酶是催化合成EβF的关键酶,目前该基因已从薄荷、香橙、花旗松、黄花蒿、洋甘菊等植物中得到分离鉴定。植物中表达EβF合成酶基因以催化法呢基焦磷酸(Farnesyl diphosphate,FPP)合成EβF是控制蚜虫危害的重要策略。文中概括了当前植物抗蚜转基因研究现状,综述了植物EβF合成酶基因及其在植物抗蚜分子育种中的应用。针对当前转基因植物的EβF生成量较低等问题,展望了EβF合成酶基因在植物抗蚜分子育种中的应用前景和研究策略。     

植物—植食性昆虫—天敌三营养层次的相互作用及其研究方法

根据国内外的最新研究成果 ,从他感化合物和植物的营养物质、有毒物质、形态特征、密度、多样性以及分布等化学和物理因子两方面阐述了植物、植食性昆虫及其天敌三营养层次间直接和间接的相互关系 ,揭示了植物在三者关系中的核心作用 ,并就目前在该领域中的一些常用的研究方法作了介绍 .     

棉铃虫与棉花相互作用研究进展

本文从昆虫对远距离寄主植物或者生境的定向 ,到达寄主植物后对取食或产卵部位的识别和选择 ,以及昆虫对寄主植物的适应及寄主植物抗虫性等 3个方面对棉铃虫与棉花的互作关系进行了综述 ,并展望了其应用前景。     

Elevational turnover in the composition of leaf miners and their interactions with host plants in Australian subtropical rainforest

Leaf miners are specialist herbivorous insects that are potentially vulnerable to environmental change because of their dependency on particular host plants. Little, however, is known about how climate affects the distribution of leaf miner communities and their interactions with host plants. Elevational gradients are useful tools for understanding how ecological communities respond to local clines in climate. Given that plant communities are known to undergo elevational turnover in response to changes in climatic conditions, we expect that leaf miner species will also change with elevation. We repeatedly hand collected leaf miners along three elevational gradients in subtropical rainforest in eastern Australia. Individual leaf miners were counted and identified to species, and their host plants were recorded. We tested if leaf miner species richness and the number of unique interactions among leaf miner and host plant species were affected by elevation. We also tested if the composition of leaf miner species and the composition of interactions between leaf miners and host plants showed a relationship with elevation. The rarefied number of unique leaf miner–host plant interactions significantly decreased with elevation, with a slight peak at approx. 700 m a.s.l., while neither rarefied or observed species richness (species density) of leaf miners nor observed numbers of unique interactions (interaction density) were significantly affected by elevation. The composition of leaf miner species and the composition of leaf miner–host plant interactions (occurrence of pairwise interactions) were significantly related to elevation. Elevational turnover in leaf miner species composition indicated that different species varied in their response to changes in biotic and/or abiotic conditions imposed by increasing elevation. Through our analyses, we identified four leaf miner species that may be locally vulnerable to climate change, as a result of their restricted elevational distribution and level of host specificity.     

寄主植物-蚜虫-天敌三重营养关系的化学生态学研究进展

综述了寄主植物－蚜虫－天敌三重营养关系的化学生态学研究,重点阐述了3个研究热点：①植物挥发性物质在蚜虫及其天敌选择寄主行为过程中的作用;②蚜虫信息素和蜜露对蚜虫天敌寄主选择行为的影响;③植物挥发性物质对蚜虫信息系作用的影响。对寄主植物－蚜虫－天敌三重营养关系的全面了解,将为蚜虫的综合治疗提供新思维。     

媒介昆虫-病毒-植物互作对生物入侵的影响

媒介昆虫-病毒-植物互作关系复杂多样。虽然相关的研究较多, 然而有关三者互作对于生物入侵的影响还知之甚少。已有证据表明, 寄主植物对病毒的敏感性和对媒介昆虫的适合性、媒介昆虫对寄主的适应能力等因素影响三者互作关系。当寄主植物易感病并且对媒介昆虫的适合性低, 而媒介昆虫对寄主植物的适应能力强时, 媒介昆虫与植物病毒之间很可能建立间接互惠关系, 这种互惠可促进媒介昆虫入侵和病毒病流行。此外, 媒介昆虫与植物病毒之间中性或偏害的互作关系对于外来生物入侵的促进作用也不容忽视。鉴于三者互作对于生物入侵的重要性, 今后需要对不同物种所组成的多种组合进行比较研究, 并采用多种方法揭示互作的生理和分子机制。     

Climate change and its effects on terrestrial insects and herbivory patterns

Climate change and extreme weather events affect plants and animals and the direct impact of anthropogenic climate change has been documented extensively over the past years. In this review, I address the main consequences of elevated CO2 and O3 concentrations, elevated temperature and changes in rainfall patterns on the interactions between insects and their host plants. Because of their tight relationship with host plants, insect herbivores are expected to suffer direct and indirect effects of climate change through the changes experienced by their host plants, with consequences to population dynamics, community structure and ecosystem functioning.     

Host‐plant genotypic diversity and community genetic interactions mediate aphid spatial distribution

Genetic variation in plants can influence the community structure of associated species, through both direct and indirect interactions. Herbivorous insects are known to feed on a restricted range of plants, and herbivore preference and performance can vary among host plants within a species due to genetically based traits of the plant (e.g., defensive compounds). In a natural system, we expect to find genetic variation within both plant and herbivore communities and we expect this variation to influence species interactions. Using a three‐species plant‐aphid model system, we investigated the effect of genetic diversity on genetic interactions among the community members. Our system involved a host plant (Hordeum vulgare) that was shared by an aphid (Sitobion avenae) and a hemi‐parasitic plant (Rhinanthus minor). We showed that aphids cluster more tightly in a genetically diverse host‐plant community than in a genetic monoculture, with host‐plant genetic diversity explaining up to 24% of the variation in aphid distribution. This is driven by differing preferences of the aphids to the different plant genotypes and their resulting performance on these plants. Within the two host‐plant diversity levels, aphid spatial distribution was influenced by an interaction among the aphid's own genotype, the genotype of a competing aphid, the origin of the parasitic plant population, and the host‐plant genotype. Thus, the overall outcome involves both direct (i.e., host plant to aphid) and indirect (i.e., parasitic plant to aphid) interactions across all these species. These results show that a complex genetic environment influences the distribution of herbivores among host plants. Thus, in genetically diverse systems, interspecific genetic interactions between the host plant and herbivore can influence the population dynamics of the system and could also structure local communities. We suggest that direct and indirect genotypic interactions among species can influence community structure and processes.     

Predicting the outcomes of a tri‐trophic interaction between an indigenous parasitoid and an exotic herbivorous pest and its host plants

Understanding the novel ecological interactions that result from biological invasions is a critical issue in modern ecology and evolution as well as pest management. Introduced herbivorous insects may interact with native plants and indigenous natural enemies, creating novel tri‐trophic interactions. To help predict the potential outcomes of novel interactions, we investigated the behavioural and physiological responses of an indigenous generalist parasitoid (Habrobracon gelechiae) to an introduced generalist herbivore (the light brown apple moth, Epiphyas postvittana) and its new host plants in California. We first examined the parasitoid's host location and acceptance on a range of nine common host plants of the moth representing distinctly different geographic origins and morphologies (to examine the effect of a known toxic plant on the parasitoid's performance, an additional toxic plant species was also tested that the moth consumes in the laboratory but does not naturally attack). The parasitoid was able to locate the host larvae on all plants equally well, although clutch size was affected by host plant. We then determined fitness of the moth and the parasitoid on four representative plants. The moth larvae suffered higher mortality and a slower developmental rate on the known toxic plant than on the other three plants, but the parasitoid's fitness correlates did not differ between the host food plants. These results show a high level of plasticity in the indigenous generalist parasitoid in its ability to exploit the exotic host on a wide range of host plants, generating an invasion‐driven novel tri‐trophic interaction.     

Contrasting structures of plant–mite networks compounded by phytophagous and predatory mite species

Differences in the feeding habits between phytophagous and predatory species can determine distinct ecological interactions between mites and their host plants. Herein, plant–mite networks were constructed using available literature on plant-dwelling mites from Brazilian natural vegetation in order to contrast phytophagous and predatory mite networks. The structural patterns of plant–mite networks were described through network specialization (connectance) and modularity. A total of 187 mite species, 65 host plant species and 646 interactions were recorded in 14 plant–mite networks. Phytophagous networks included 96 mite species, 61 host plants and 277 interactions, whereas predatory networks contained 91 mite species, 54 host plants and 369 interactions. No differences in the species richness of mites and host plants were observed between phytophagous and predatory networks. However, plant–mite networks composed of phytophagous mites showed lower connectance and higher modularity when compared to the predatory mite networks. The present results corroborate the hypothesis that trophic networks are more specialized than commensalistic networks, given that the phytophagous species must deal with plant defenses, in contrast to predatory mites which only inhabit and forage for resources on plants.     

Modelling the Population Dynamics of Root Hemiparasitic Plants Along a Productivity Gradient

Root hemiparasitic plants interact with their host plants through parasitism and competition. The interactions can be divided into aboveground and belowground interactions. Because both groups of plants are autotrophic, they compete for light aboveground. Belowground interactions are more complex. The host plants compete for resources in the soil and the hemiparasitic plants prey on the host plants through haustoria, using the hosts as the main source of water and nutrients. In this paper, we modeled the relationship between these two plant types, extending the well-known Rosenzweig-MacArthur predator-prey model to cover both light competition and intra-specific parasitism among hemiparasites. We included a realistic relationship of carrying capacity to environmental productivity and followed model behavior on a productivity gradient. The model shows that, at very low productivities, there are only a few poor hosts and hemiparasites have no chance to persist. As productivity increases, there is a range of productivity where both plant types coexist. A further increase in productivity gets the system out of the coexistence range, and only host plants survive. This final prediction successfully explains patterns observed in empirical data, contrary to the results of an earlier, oversimplified model of the explored interaction. Comparison of various models demonstrates that the model is able to reproduce the decline of hemiparasites with increasing productivity only when competition for light is included.