植物间挥发物信号的研究进展

植物VOCs信号是植物间进行信息交流的"语言",可由多种生物和非生物因素诱导产生。非寄生植物释放的VOCs信号可影响其所在群落中其它植物的种子萌发与幼苗生长;而寄主植物释放的VOCs信号却是诱导寄生植物种子萌发和幼苗生长的信号物质。VOCs作为植物间的伤害信息可以诱导临近的同种或异种植物做好防御准备,从而通过主动或间接防御以减少外界的伤害。植物间通过VOCs信号进行信息交流,从而实现其繁衍与防御。该文通过对VOCs信号的种类、诱导产生因素、传递及作用进行综述,以期对VOCs信号的研究有所帮助。     

寄生植物对寄主植物的化学识别

植物间寄生关系的研究近年来受到了广泛的重视。大量的研究表明,寄主释放的次生物质对植物间寄生关系的建立和维持起了重要的调节作用。寄主植物的次生物质对寄生植物的化学防御和昆虫授粉等生态功能起重要的作用,寄主植物次生物质对寄生植物生理与生态的调节作用是受寄生植物基因调节的。更为重要的是寄主植物释放的次生物质成为寄生植物的种子萌发和吸器发生的异源识别物质。能够刺激寄生植物种子萌发的次生物质主要是倍半萜和氢醌类物质,而诱导吸器发生的物质则是酚酸、醌和黄酮类化合物,诱导吸器发生的核心结构是对苯醌。这些异源识别物质大多是寄主植物释放的化感抑制物质,显示寄生植物在化学防御方面要比寄主植物高级。异源识别化合物的活性与其氧化潜力显著相关。由于寄生植物中存在一抑制异源识别物质诱导吸器发生的调节过程,因此吸器的产生与寄生植物根部接触异源识别物质的浓度与时间呈正相关关系,这一调节过程对寄生植物准确识别寄主并寄生其上是十分重要的。对寄生植物和寄主植物间的化学识别关系的揭示有助于人们防治有害寄生植物和开发利用有价值的寄生植物资源。     

根寄生植物种子萌发刺激物研究进展

根寄生植物是被子植物中一类寄生在寄主根部, 以摄取寄主水分和营养物质为生的特殊植物类群, 其种子萌发需要寄主萌发刺激物的诱导。该文主要阐述根寄生植物种子萌发的特异性, 以及目前已发现的刺激种子萌发的信号物质及其调节机制和生物合成途径, 并就萌发刺激物的识别机制及其在根寄生植物或丛枝菌根真菌与寄主建立寄生关系过程中所起的作用进行综述, 提出根寄生植物种子萌发研究中存在的问题, 并对其研究前景进行了展望。     

藻类挥发性有机化合物研究进展

在水域生态系统中, 藻类释放的挥发性有机化合物(VOCs)种类众多, 主要有萜烯类、醛类、醇类、酯类、酮类、脂肪族烃、芳香族、硫化物和卤化物。这些VOCs通过不同的次生代谢途径形成, 可为多种环境因素所诱导产生。在逆境胁迫下, VOCs具有提高藻细胞抗逆性的作用。当VOCs释放到水体中后, 可为同种藻细胞传递胁迫信息, 使感受细胞做好防御准备。对于异种藻细胞, VOCs通过化感作用抑制其生长, 从而保证VOCs释放者的竞争优势。此外, VOCs还可驱避捕食者, 保护藻细胞免受伤害。未被感受者利用的VOCs经挥发进入大气层后, 会参与水域上空二次有机气溶胶的形成。通过对藻类VOCs的种类、形成途径、诱导释放因素及其生态作用进行综述, 以期对藻类VOCs的研究有所帮助。     

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。     

寄生植物种子萌发特异性及其与寄主的识别机制

寄生植物广泛分布于不同的生态环境中,并具有不同的生育习性及与寄主识别特性.本文阐述了根寄生植物列当属和独脚金属种子萌发的特异性,以及目前已发现的寄生植物种子萌发的信号物质,并就不同萌发信号物质、植物激素、真菌代谢物在寄生植物种子识别寄主中的作用以及寄生植物种子预培养阶段的呼吸作用特性与萌发信号物质的活化机理等做了综述.探讨了各种列当不同分化类型的愈伤组织诱导、离体无菌侵染新系统及其在寄生植物与寄主互作识别研究中的应用,提出了寄生植物与寄主识别机理研究中存在的问题并对研究前景进行了展望.     

种子萌发和幼苗生长对沙丘环境的适应机制

综述了植物沙生适应机制的研究及其进展.一些植物的种子在刚成熟时具有休眠特性.种子需要适度沙埋促进萌发并实现幼苗定居,但过度沙埋则会抑制种子萌发和出苗.在沙层深处,没有萌发的种子会进入休眠状态,形成土壤种子库.幼苗通过增加节数和延长节间来适应沙埋.沙埋深度超过植物的忍耐限度会抑制幼苗生长,甚至导致幼苗死亡.沙生植物必须适应其他环境因子,如盐风与土壤盐分、昆虫采食、土壤养分亏缺等,才能在沙丘上成功生长.沙蚀可导致幼苗根系暴露并干燥脱水.一些沙漠植物的幼苗在萌发后可忍耐一段时期的干燥,水分条件得到满足之后,幼苗能够恢复生长.     

花生种子的磁处理对其萌发及幼苗生长的影响

本试验着重研究了用交、直流磁场对花生种子进行处理后,在种子萌发及幼苗生长过程中产生的影响。结果表明,一定强度的交流或直流磁场对种子的萌发及幼苗生长有一定的促进作用。处理过的种子存放一年后,磁场对种子萌发的作用依然存在。     

花生种子的磁处理对其萌发及幼苗生长的影响

本试验着重研究了用交、直流磁场对花生种子进行处理后,在种子萌发及幼苗生长过程中产生的影响。结果表明,一定强度的交流或直流磁场对种子的萌发及幼苗生长有一定的促进作用。处理过的种子存放一年后,磁场对种子萌发的作用依然存在。     

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。     

损伤冷蒿挥发性有机化合物(VOCs)成分分析及其对牧草根系生长发育的影响

采用GC-MS测定损伤冷蒿VOCs的主要成分,并通过生物测定的方法研究损伤冷蒿VOCs对牧草幼苗根系生长发育的影响。结果表明:损伤冷蒿释放30种VOCs,包含萜烯类、醇类、酯类、醛类和酮类等5类化合物,其中相对含量高于1%的化合物共占VOCs总量的97.37%,桉树脑含量最高(22.43%)。损伤冷蒿释放的VOCs极显著(P0.01)的抑制草木樨、苏丹草、披碱草和冰草幼根的伸长,以及苏丹草侧根与冰草须根的发育,抑制率分别为51.55%、55.34%、37.57%、48.68%、93.04%和25.00%;同时也极显著抑制4种牧草幼根生物量的积累(P0.01)。损伤冷蒿VOCs影响牧草根部中柱组织结构的分化,使草木樨中柱内木质部、韧皮部与形成层不能正常分化;苏丹草、披碱草和冰草的凯氏带发育不完整。由此可见,损伤冷蒿VOCs对牧草根系生长发育具有明显的抑制作用。     

Growth form rather than phylogenetic relationship predicts broad volatile emission patterns in the Brassicaceae

Volatile organic compounds (VOCs) released from plants are known to mediate indirect defense against herbivores and trigger intra- and interplant signaling. While systemic defense response can be mediated both via volatile and vascular signals, it is not clear whether common ancestry and/or plant growth forms influence the choice of either mode in planta. We hypothesize that larger woody plants with a complex anatomy should rely more on volatile-mediated signaling, apparently to circumvent vascular restrictions that slow down the communication over a large distance. On the other hand, in smaller herbaceous plants faster systemic response can be achieved via vascular signaling. To investigate whether plant VOCs emission is related to plant phylogeny or growth form, we studied the composition of herbivory-induced plant volatiles in 13 Brassicaceae species representing all four evolutionary lineages, because this family is characterized by both a well-resolved phylogeny and highly diverse growth forms. Our results revealed that woody species consistently emitted a more complex blend of volatiles than herbaceous species. However, phylogenetic relatedness of the species did not explain the observed volatile emission patterns. This emphasizes the influence of growth form, rather than phylogenetic relationships on the variation in plant volatile emissions. Our findings suggest that woody, perennial plant species emit diverse VOCs, likely because these compounds comprise a more efficient mode of defense response in these large, anatomically complex plants.     

Arabidopsis thaliana for testing the phytotoxicity of volatile organic compounds

Geosmin and C-8 hydrocarbons are among the major volatile organic compounds (VOC) responsible for the distinctive, musty odor of filamentous fungi. In this study, we developed a plant bioassay for testing the possible toxicity of these compounds, as well as four air freshener products sometimes used to mask their odor. Seeds and vegetative plants of Arabidopsis thaliana were exposed to 1 ppm of 14 different volatile treatments (both single compounds and mixtures) for 72 h and monitored for germination rate, seedling formation, vegetative plant vigor and chlorophyll concentration. All VOCs tested had some inhibitory effect on seed germination or seedling formation; 1-octen-3-one was the most active, giving almost complete inhibition of germination. Geosmin did not prevent germination (radicle protrusion) but seedling formation was arrested 90 %. Of solvents and fragrance products tested, only the scented oil product was as active as the C-8 biogenic compounds in inhibiting seed germination and seedling formation. Two-week-old plants exposed to 1 ppm of individual fungal VOCs for 72 h all exhibited some degree of stress symptoms including smaller leaf size and weight, discoloration, leaf curling, small necrotic lesions, and reduced chlorophyll concentration. Two-week-old vegetative plants exposed to solvents and air freshener products were generally smaller in size. The single most phytotoxic compound tested was 1-octen-3-one which almost completely inhibited seed germination and was lethal to vegetative phase plants. Formaldehyde at 1 ppm killed 2-week-old seedlings but had little effect on seed germination. In conclusion, the A. thaliana bioassay provides an inexpensive approach for testing the toxicity of gas phase molecules.     

植物挥发性信号物质介导抗性的生态功能

植物产生的挥发性化合物能够作为媒介参与植物与周围环境之间的信息交流及相互作用。植物挥发性物质在吸引传粉者、促进种子传播、抑制其它植物种子萌发等方面具有重要的作用。近年来,关于植物挥发性物质在生态系统中的信号作用研究已经成为国内外的研究热点,受到广泛关注。总结了植物挥发性物质作为信号物质在提高植物抗性方面的国内外研究成果,阐述了植物挥发性物质不仅能够直接提高植物的抗性,而且可以作为信号物质在同株、同种异株和不同种植物之间进行传递,进而间接提高目标植物的抗性。最后,还对植物挥发性物质的研究方法和潜在的生态功能进行了探讨。     

Irrigation and fertilization effects on seed number,size, germination and seedling growth: implications for desert shrub establishment

Plants with limited resources adjust partitioning among growth, survival, and reproduction. We tested the effects of water and nutrient amendments on seed production, size, and quality in Sarcobatus vermiculatus (greasewood) to assess the magnitude and importance of changes in reproductive partitioning. In addition, we assessed interactions among the environment of seed-producing plants (adult plant scale), seed size, and seedling microenvironment (seedling scale) on successful seedling establishment. Interactions of these factors determine the scale of resource heterogeneity that affects seedling establishment in deserts. Both total number of seeds produced per plant and seed quality (weight and germination) increased significantly in the enriched treatment in a 3-year field experiment. Seedling length 3 days after germination and seed N concentration, other measures of seed quality, were higher for seed from both irrigated and enriched plants than for seed from control plants. Field S. vermiculatus seed production and quality can be substantially increased with irrigation and nutrient enrichment at the adult plant scale and this allows management of seed availability for restoration. However, based on a greenhouse study, seedling environment, not the environment of the seed-producing plant or seed size, was the most important factor affecting seedling germination, survival, and growth. Thus it appears that production of more seed may be more important than improved seed quality, because higher quality seed did not compensate for a low-resource seedling environment. For both natural establishment and restoration this suggests that heterogeneity at the scale of seedling microsites, perhaps combined with fertilization of adult shrubs (or multi-plant patches), would produce the greatest benefit for establishing seedlings in the field.     

植物化学通讯研究进展

 生物的信息传递是生命科学中引人入胜的研究领域之一,生物种间种内和个体内都存在着物理和化学等各种信息交流方式。植物种间种内是否通过物理信号进行通讯交流还是一个未知数,但邻近的同种或异种植物通过化学物质为媒介的通讯关系确是客观存在的。最近,愈来愈多的研究证明：许多陆生植物种可以合成并释放特定的次生物质,这些次生物质可以通过空气和土壤两种载体进行信息传递,尤其是在植物受到侵袭和寄生条件下。茉莉酮酸甲酯、水杨酸甲酯和乙烯等挥发性次生物质被确证为以空气为媒介进行植物种间和种内通讯的化学信号分子。植物根分泌的黄酮和氢醌等分子也可以经土壤媒介传递信息。由于在自然条件下植物根系分泌物的收集和活性信号分子的俘获及鉴定技术还未能突破,这增加了以土壤为媒介的植物种间和种内化学通讯关系研究的难度。但不论如何,植物的化学通讯是植物种间和种内交流的主要方式,植物间的化学通讯关系的研究还处于突破的前夜,这方面的任一研究成果都会引起世界性的关注。因此,破译植物种间和种内化学通讯密码具有重要的学术价值。     

Sustained growth promotion in arabidopsis with long-term exposure to the beneficial soil bacterium Bacillus subtilis (GB03)

Volatile emissions from the commercial growth promoting soil bacterium Bacillus subtilis (GB03) are effective in augmenting short-term growth, photosynthetic capacity and salt tolerance in Petri-dish grown arabidopsis seedlings. In contrast, the impact sustained GB03 volatile exposure on plant growth and development has yet to be examined. here is provided physical and physiological data establishing that bacterial volatiles induce long-term growth promotion, elevated photosynthetic capacity and iron accumulation, as well as delayed albeit higher seed count compared with water-treated control plants. Plants were grown unrestricted in double Magenta boxes containing solid MS media for up to twelve weeks with GB03 volatiles introduced in separate containers within the chamber so that plant bacterial interactions were only by air-borne transmission. These results establish that GB03 volatiles induce sustained beneficial effects on Arabidopsis growth including robust and extended vegetative growth followed by elevated seed set.Key words: Bacillus subtilis (GB03), photosynthetic efficiency, plant growth promoting rhizobacteria (PGPR), seed set, volatile organic compound (VOCs)     

氢气调节植物生长发育和提高植物抗逆性的研究进展

氢气作为新发现的活性气体被广泛研究。在植物生长发育方面,氢气具有促进种子发芽、幼苗发育、不定根生长等作用;在植物遭受逆境胁迫过程中,氢气通过调控抗氧化酶活性、抗氧化物质的生成及其相应的转录本来应对胁迫带来的氧化损伤,提高植物对干旱、盐胁迫、重金属胁迫、除草剂、紫外照射等胁迫的抗性,同时氢气还可以调控与抗病虫害等胁迫相关基因的表达。该文对国内外有关氢气在促进植物生长发育和提高植物抗性方面的作用,以及逆境胁迫下氢气作为信号分子通过调控抗氧化防御系统提高植物抗逆性的机制进行综述,以期更好地了解和促进氢气在农业科学上的研究与应用。