植物抗虫“防御警备”:概念、机理与应用

植物抗虫"防御警备"是指受到某些生物或者非生物因子刺激警备后,植物会提前做好抗虫防御准备,之后当再次受到害虫袭击时,植物会产生更加快速和强烈的抗虫防御反应,从而使自身抗虫性显著提高.这是近年来新发现的植物防御害虫的一种策略,是一种特殊的诱导抗虫机制.植食性昆虫的取食、分泌物、产卵、为害诱导的植物挥发物(HIPVs)以及某些有益微生物、植物营养元素、重金属和一些化学物质均可以引起植物产生抗虫防御警备.防御警备具有抗性高效、持久、环境友好,甚至可以遗传到子代等优点.本文综述了近年来有关植物抗虫防御警备的研究,主要概括了植物抗虫防御警备的一般特征、刺激警备因子和形成机制,并对其在生产实践中的应用前景进行了简要分析,提出了这一领域尚未解决的问题和亟待深入的研究方向.通过合适的方法使植物产生抗虫防御警备可以大大减少杀虫剂的使用,成为害虫综合防治的重要手段.     

组蛋白修饰调控植物对胁迫的记忆与警备抗性的研究进展

植物扎根土壤,面对不利的环境胁迫无法逃避。然而,植物已经进化出对环境胁迫的记忆(stress memory)与警备抗性(或防御警备defense priming)等机制适应环境。环境胁迫在短时间内无法改变植物的DNA碱基序列,因此表观遗传被认为是植物对环境胁迫产生记忆和产生防御警备的主要机制,而组蛋白修饰被认为是最重要的机制,为胁迫记忆提供了可能。本文综述了非生物和生物胁迫下植物分别以胁迫记忆和防御警备机制为主导的组蛋白修饰参与抵御不良环境的最新进展,并提出该研究领域存在的问题和今后研究的重点与方向。深入探究组蛋白修饰与植物适应环境胁迫的关系,可为提高植物抗性、植物表型塑造、器官再生和作物改良等方面提供理论和技术指导。     

萜类化合物在植物间接防御中的作用

植物受到虫害后释放萜类化合物吸引害虫天敌的间接防御是一种新颖且环保的抗虫模式。植物受到害虫危害等因素诱导后做出响应,在体内经过一系列复杂调控,释放萜类物质,害虫天敌顺着这些萜类物质找到害虫,通过捕食或寄生于害虫体内的方法来消灭害虫。在实际应用中,可考虑利用直接和间接防御相结合的防治方法。     

外源茉莉酸和茉莉酸甲酯诱导植物抗虫作用及其机理

综述了茉莉酸(jasmonic acid, JA)和茉莉酸甲酯(methyl jasmo nate, MJA)的分子结构和应用其诱导的植物抗虫作用及其机制。植物受外源茉莉酸或茉莉酸甲酯刺激后,一条反应途径是由硬脂酸途径激活防御基因,另一条途径是直接激活防御基因。防御基因激活后导致代谢途径重新配置,并可能诱导植物产生下列4种效应：（1）直接防御,即植物产生对害虫有毒的物质、抗营养和抗消化的酶类,或具驱避性和妨碍行为作用的化合物;（2）间接防御,即产生吸引天敌的挥发物;（3）不防御,即无防御反应;（4）负防御,即产生吸引害虫的挥发物。     

丛枝菌根真菌摩西管柄囊霉侵染增强番茄对机械损伤的响应

植食性昆虫取食会给植物造成机械损伤并激活植物的防御反应,而与有益微生物共生是否可以增强植物对机械损伤的响应对植物抗虫有重要意义.本研究在番茄根系被丛枝菌根真菌摩西管柄囊霉侵染后,研究机械损伤对番茄防御反应的影响.结果表明: 预先接种菌根真菌的番茄叶片受到机械损伤处理(FD)后,叶片苯丙氨酸解氨酶(PAL)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、多酚氧化酶(PPO)和过氧化氢酶(CAT)活性,以及叶片和根系苯丙氨酸解氨酶基因(PAL)和β-1,3-葡聚糖酶基因(PR2)的转录水平均显著高于只进行机械损伤的处理(D)、只接种摩西管柄囊霉的处理(F),以及既未接种菌根菌也未进行机械损伤的健康番茄植株(CK).虽然D和 F处理也可诱导部分酶活性及基因转录水平升高,但FD处理诱导的防御反应更迅速和强烈.表明丛枝菌根真菌侵染可以警备(prime)番茄对机械损伤做出更快速和强烈的响应.     

昆虫对植物抗虫性的诱导

植物的抗虫性主要表现为受遗传因素控制的遗传抗性和受环境因素控制的生态抗性两个方面。植物的抗性主要由遗传因素决定,但其抗性表达和抗虫幅度又受到环境因子的影响。环境因子可改变植物的生理状态和理化性质,使植物不合适作为某种昆虫的寄主,从而提高了植物的抗性水平。植食性昆虫对植物抗虫性的诱导是环境影响抗性表达的一个重要方面,它是植物对取食者的一种重要的防御策略,同时也是植物与植食者协同进化的结果,进一步了解和充分发挥诱导抗性的作用,对抗虫有种工作和害虫的综合治理都有指导意义。三植食性昆虫对植物抗虫性的诱导…     

茉莉酸类化合物:从植物的诱导抗虫防御反应到生长-防御权衡

茉莉酸类化合物(jasmonates, JAs)可外源诱导植物产生抗虫防御反应.因此,JAs在植物生理及植物保护学领域具有十分重要的研究价值.本文归纳了近20年来在约40种植物上外源施用JAs对鳞翅目、半翅目等植食者及其天敌所产生的生态影响,并从JAs诱导植物产生的直接与间接抗虫反应、诱导系统抗性、诱导方法、田间诱导抗虫表现、应用现状等方面对JAs诱导植物抗虫的研究现状进行了系统的总结.同时,本文结合最新研究结果,从植物体内信号交流、JA信号途径节点调控等方面,对植物体内与JA途径相关的生长-防御“权衡”进行了综述.最后,本文对今后外源JAs诱导植物抗虫研究的发展方向与重点方面进行了分析和展望,以期促进相关研究及JAs田间应用的创新发展.     

植物创伤诱导的挥发物及其信号功能

植物在受到动物或病原侵害时,会释放特异的挥发作作为信号,这些信号分子是植物防御系统的重要组成部分,文章对植物创伤诱导挥发物的种类,诱导因子及生理作用等的研究进展,以及这一领域的研究潜力和发展方向作了评述。     

昆虫与植物关系的研究进展和前景

本文综述昆虫与植物之间关系的研究概况，包括历史渊源、昆虫选择寄主植物的生理机制，植物对虫害的反应、用抗虫基因在作物中移植以防治害虫和展望。着重叙述昆虫神经中枢对于植物理化特性所产生的感觉内导的综合作用，植物蒙受虫害后的补偿作用及由此诱导所产生的化学防御作用。讨论了以抗虫基因移植于农林作物来防治害虫是否会引起昆虫对这种新育成的植物产生适应或抗性。昆虫与植物之间的关系是一个重要的科研领域，对其发展前景     

虫害诱导植物间接防御反应的激发与信号转导途径

植物通过产生和释放挥发性物质增加植食性昆虫的天敌对其寄主或猎物的定位,减少植食性昆虫对植物的取食,从而达到间接防御的目的。植物对植食性昆虫所做出间接防御反应激发因子和信号转导途径的研究,对应用虫害诱导植物挥发物引诱害虫天敌,并进一步从植物、植食性昆虫及其天敌间三级营养关系,研究动植物协同进化机理和病虫害防治具有深远意义。本文根据国内外最新研究进展,对虫害诱导植物间接防御反应的激发因子,昆虫取食信号的转导途径及对植物间接防御相关基因的激活等方面进行了系统地综述。     

Ecological and Evolutionary Interactions between Wild Crucifers and Their Herbivorous Insects

Abstract Insects feeding on ten species of wild crucifer were investigated. Differences in host plant range and insect community structure were examined with regard to anti-herbivore defense mechanisms. Most of the crucifer species deterred insect herbivory by disappearing in the summer or by lowering their intrinsic quality as food for insects. Species with these defense mechanisms were exploited by only a few specialized herbivorous insects that seemed to have counter defenses. The plants without these defense mechanisms were used by many herbivorous insect species. Rorippa indica lacked direct defenses, but supported a low total density of herbivore individuals. This crucifer has an indirect defense mechanism: ants attracted to floral nectar defended the plant from deleterious herbivores. Crucifers that disappeared seasonally lacked other anti-herbivore defense mechanisms. This suggests that the phonological response is an alternative other responses to herbivore attack.     

Priming of antiherbivore defensive responses in plants

Defense priming is defined as increased readiness of defense induction. A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses, both biotic and abiotic, and upon the following stimulus, induce defenses more quickly and strongly. For instance, some plants previously exposed to herbivore‐inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger defense activation and enhanced insect resistance when challenged with secondary insect feeding. Research on priming of antiherbivore defense has been limited to the HIPV‐mediated mechanism until recently, but significant advances were made in the past three years, including non‐HIPV‐mediated defense priming, epigenetic modifications as the molecular mechanism of priming, and others. It is timely to consider the advances in research on defense priming in the plant–insect interactions.     

6种防御酶调控植物体应答虫害胁迫机制的研究进展

植物防御体系应对虫害胁迫产生一系列防御性生理生化反应,其中防御酶活性呈现显著变化.本文综述了超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、多酚氧化酶(PPO)、脂氧合酶(LOX)和苯丙氨酸解氨酶(PAL) 6种常见防御酶应对虫害胁迫的机制,解析了6种防御酶的作用机理及其异同.梳理了6种防御酶应对虫害胁迫而相互协调的程序,总结了植物体遭虫害胁迫之后防御酶活性的变化及其与防御酶基因的关联,提出了植物体防御酶机制研究中的重要问题并展望前景.     

Insect herbivory and plant adaptation in an early successional community*

To address the role of insect herbivores in adaptation of plant populations and the persistence of selection through succession, we manipulated herbivory in a long‐term field experiment. We suppressed insects in half of 16 plots over nine years and examined the genotypic structure and chemical defense of common dandelion (Taraxacum officinale), a naturally colonizing perennial apomictic plant. Insect suppression doubled dandelion abundance in the first few years, but had negligible effects thereafter. Using microsatellite DNA markers, we genotyped >2500 plants and demonstrate that insect suppression altered the genotypic composition of plots in both sampling years. Phenotypic and genotypic estimates of defensive terpenes and phenolics from the field plots allowed us to infer phenotypic plasticity and the response of dandelion populations to insect‐mediated natural selection. The effects of insect suppression on plant chemistry were, indeed, driven both by plasticity and plant genotypic identity. In particular, di‐phenolic inositol esters were more abundant in plots exposed to herbivory (due to the genotypic composition of the plots) and were also induced in response to herbivory. This field experiment thus demonstrates evolutionary sorting of plant genotypes in response to insect herbivores that was in same direction as the plastic defensive response within genotypes.     

Maize plants prime anti-herbivore responses by the memorizing and recalling of airborne information in their genome

Intact maize plants prime for defensive action against herbivory in response to herbivore-induced plant volatiles (HIPVs) emitted from caterpillar-infested conspecific plants. The recent research showed that the primed defense in receiver plants that had been exposed to HIPVs was maintained for at least 5 d after exposure. Herbivory triggered the receiver plants to enhance the expression of a defense gene for trypsin inhibitor (TI). At the upstream sequence of a TI gene, non-methylated cytosine residues were observed in the genome of HIPV-exposed plants more frequently than in that of healthy plant volatile-exposed plants. These findings provide an innovative mechanism for the memory of HIPV-mediated habituation for plant defense. This mechanism and further innovations for priming of defenses via plant communications will contribute to the development of plant volatile-based pest management methods in agriculture and horticulture.     

Solar ultraviolet-B radiation and insect herbivory trigger partially overlapping phenolic responses in Nicotiana attenuata and Nicotiana longiflora

BACKGROUND AND AIMS: Plants exposed to solar ultraviolet-B radiation (UV-B, 280-315 nm) frequently suffer less insect herbivory than do plants that receive attenuated levels of UV-B. This anti-herbivore effect of solar UV-B exposure, which has been documented in several ecosystems, is in part mediated by changes in plant tissue quality. Exposure to UV-B can modify the abundance of a number of secondary metabolites, including phenolic compounds with potential impacts on insect herbivores. The aim of this study is to assess the potential anti-herbivore role of UV-B-induced phenolic compounds by comparing the phenolic profiles induced by UV-B and simulated insect herbivory in two wild species of the genus Nicotiana. METHODS: Plants grown under field and glasshouse conditions were exposed to contrasting levels of UV-B. Half of the plants of the attenuated UV-B treatment were given a simulated herbivory treatment, where leaves were mechanically damaged and immediately treated with oral secretions of Manduca sexta caterpillars. This treatment is known to mimic the impact of real herbivory on the expression of plant defences in Nicotiana. Phenolic profiles induced by UV-B and simulated herbivory were characterized using high-performance liquid chromatography-mass spectrometry (HPLC-MS). KEY RESULTS: UV-B induced the accumulation of several UV-absorbing phenolic compounds that are known to play a significant role in UV-B screening. Interestingly, there was a significant convergence in the phenolic profiles induced by UV-B and simulated herbivory: chlorogenic acid and dicaffeoylspermidine isomers, in particular, displayed a similar pattern of response to these stimuli. In contrast, rutin, the only flavonoid that accumulated in significant quantities in the experiments, was only induced by UV-B. CONCLUSIONS: The results suggest that the anti-herbivory effect induced by UV-B may be mediated at least in part by the accumulation of phenylpropanoid derivatives that are similar to those induced by the plant in response to insect herbivory.     

Plant latex and other exudates as plant defense systems: roles of various defense chemicals and proteins contained therein

Plant latex and other exudates are saps that are exuded from the points of plant damage caused either mechanically or by insect herbivory. Although many (ca. 10%) of plant species exude latex or exudates, and although the defensive roles of plant latex against herbivorous insects have long been suggested by several studies, the detailed roles and functions of various latex ingredients, proteins and chemicals, in anti-herbivore plant defenses have not been well documented despite the wide occurrence of latex in the plant kingdom. Recently, however, substantial progress has been made. Several latex proteins, including cysteine proteases and chitin-related proteins, have been shown to play important defensive roles against insect herbivory. In the mulberry (Morus spp.)-silkworm (Bombyx mori) interaction, an old and well-known model system of plant-insect interaction, plant latex and its ingredients - sugar-mimic alkaloids and defense protein MLX56 - are found to play key roles. Complicated molecular interactions between Apocynaceae species and its specialist herbivores, in which cardenolides and defense proteins in latex play key roles, are becoming more and more evident. Emerging observations suggested that plant latex, analogous to animal venom, is a treasury of useful defense proteins and chemicals that has evolved through interspecific interactions. On the other hand, specialist herbivores developed sophisticated adaptations, either molecular, physiological, or behavioral, against latex-borne defenses. The existence of various adaptations in specialist herbivores itself is evidence that latex and its ingredients function as defenses at least against generalists. Here, we review molecular and structural mechanisms, ecological roles, and evolutionary aspects of plant latex as a general defense against insect herbivory and we discuss, from recent studies, the unique characteristics of latex-borne defense systems as transport systems of defense substances are discussed based on recent studies.     

昆虫取食诱导的植物防御反应

植物被昆虫取食后可产生直接防御或间接防御。直接防御通过增加有毒的次生代谢产物或防御蛋白对昆虫生理代谢产生不利的影响,但对植物的消耗较大。间接防御通过释放挥发性化合物吸引天敌昆虫,并以此控制植食性昆虫。特异性的昆虫激发子(insect specific elicitors)能够诱导挥发性化合物的释放。多种信号途径参与昆虫取食诱导的植物防御反应,它们之间的相互作用协同或拮抗。了解昆虫取食诱导的植物防御反应,对于害虫综合治理策略的完善具有重要的意义。     

Metal accumulation and its effect on leaf herbivory in an allopolyploid species Arabidopsis kamchatica inherited from a diploid hyperaccumulator A. halleri

Excessive amounts of metal ions in soil are toxic for most plant species, yet metal can also facilitate plant survival by elemental defense against herbivores and pathogens. Zinc and cadmium hyperaccumulation in Arabidopsis halleri is known to be effective for the defense against natural enemies. The allotetraploid species A. kamchatica, derived from A. halleri and a non-hyperaccumulator A. lyrata, has a lower hyperaccumulation level of zinc than A. halleri, but its significance for elemental defense remains unknown. In this study, we evaluated the accumulation levels of zinc and cadmium in the allotetraploid compared with its diploid progenitors, and evaluated the contribution of metal treatments to anti-herbivore resistance under field conditions. The accumulation level of zinc in A. kamchatica was intermediate between the progenitors, but that of cadmium was lower than in both diploid progenitors. The elemental defense of A. kamchatica and A. halleri was supported by a field experiment comparing the herbivory level between a control group and metal-supplemented plants. Moreover, the effect of elemental defense was lower in A. kamchatica than in the hyperaccumulator progenitor A. halleri, which is consistent with the metal accumulation level. This result reveals that the allotetraploid plant inherited its hyperaccumulating ability from one progenitor as an advantageous trait but at an intermediate level.