植物脂氧合酶研究进展

脂氧合酶（简称LOX）是广泛分布的含有非血红素离子的双加氧酶,它是植物十八碳酸代谢途径的关键酶．该途径也称LOX途径。因为该酶作用的产物在植物的生长发育过程中以及在植物对环境胁迫反应中起着重要的作用,因此一直是人们研究的热点。目前对于植物脂氧舍酶的研究主要集中在脂氧合酶基因的表达调控、LOX途径的生化研究以及代谢产物的生理功能这几个方面。     

水杨酸诱导美登木悬浮细胞产生脂氧合酶及多羟基脂肪酸的研究

水杨酸 (SA)可诱导云南美登木 (Maytenushookeri)悬浮培养细胞产生 9 脂氧合酶(9 lipoxygenase ,9 LOX)。通过LC ESI MS测定SA诱导下悬浮培养系中多羟基脂肪酸的含量变化 ,发现用浓度为 80 0 μmol L的SA诱导培养 18h ,悬浮细胞产生最大量的三羟基十八碳烯酸。同时 ,通过对比不同羟基十八碳烯酸含量的变化 ,推测在SA诱导下 ,9 LOX介导的十八碳酸途径中有环氧中间体的生成。     

5-脂氧合酶抑制剂的研究进展

脂氧合酶是一种含铁的氧化还原酶，存在于动植物的组织和细胞中。脂氧合酶主要分为1、3、5、8、12、15-脂氧合酶6种亚型。5-脂氧合酶(5-lipoxygenase,5-LOX)是LOX同工酶中研究较为深入的非血红素铁蛋白氧化代谢酶，是许多高活性氧化脂质生物合成中的关键酶，参与多种炎症性疾病，如炎症、哮喘、脑缺血、部分恶性肿瘤及阿尔茨海默症等疾病的发生和发展过程。因此，开发有效的5-LOX抑制剂对治疗上述疾病至关重要。本文介绍了5-LOX抑制剂的研究成果，并对其分类、来源、治疗药效和优缺点进行了讨论，为深入研发创新型5-LOX抑制剂提供理论依据。     

12/15 脂氧酶在脑卒中的作用研究进展

脂氧合酶(LOX)是一类广泛存在于动植物中的非血红素铁蛋白,催化底物生成各种类花生酸物质,与人体的肿瘤、哮喘、炎症、动脉硬化等疾病密切相关。12/15脂氧酶(12/15-LOX)是一种脂质过氧化物酶,可以催化亚油酸,花生四烯酸等多不饱和脂肪酸生成具有生物活性的代谢产物,通过信号转导在许多病理生理过程中发挥着重要的作用,有研究表明,12/15-LOX通路可以刺激炎症因子的产生,参与多种炎性反应,而在脑卒中的发生发展以及病理过程中始终伴随的炎性反应,炎症及细胞因子等对脑卒中有一定的影响,在脑卒中炎症反应继发性脑组织损伤病理发展过程中起着重要的作用。因此,研究12/15-LOX与脑卒中炎症的关系,可以为临床治疗脑卒中提供新的靶点。本文就12/15-LOX在脑卒中后炎症反应中的作用做简要介绍。     

几丁质酶与植物防卫反应

几丁质酶广泛存在于自然界,亦普遍存在于高等植物中,但在植物体内,至今尚未发现几丁质酶作用的底物。最近的研究不断发现植物防卫反应诱导表达的基因中包含着编码几丁质酶的基因［１］。许多研究已经表明,几丁质酶在植物体内的诱导与积累,对于增强植物防卫能力发挥着重要作用［２］,而植物自身防卫反应是目前植物分子生物学研究的热点之一。本文将着重介绍几丁质酶的特性、诱导及其参与防卫反应的机制的研究进展     

几丁质酶与植物防卫反应

几柄质酶广泛存在于自然界,亦普遍存在于高等植物中,但在植物体内,至今尚未发现几丁质酶作用的底物。最近的研究不断发现植物防卫反应诱导表达的基因中包含着编码几丁质酶的基因。许多研究已经表明,几丁质酶在植物体内的诱导与积累,对于增强植物防卫能力发挥着重要作用,而植物自身防卫反应是目前植物分子生物学研究的热点之一。     

植物几丁质酶及其在抗真菌病害中的应用

植物几丁质酶的研究是抗真菌基因工程的热点之一。几丁质酶能够水解真菌细胞壁的主要成分几丁质,在植物抗真菌病害反应中发挥重要的作用。介绍了几丁质酶的基本生物学特性、基因的诱导表达,并对植物几丁质酶基因在抗真菌病害基因工程中的应用进行了阐述。     

5-脂氧合酶及其抑制剂

5-脂氧合酶（5-lipoxygenase, 5-LOX）是生物体内一种重要的双加氧酶.5-LOX是催化花生四烯酸（arachidonic acid,AA）生成白三烯类（leukotrienes, LTs）的关键酶. LTs是重要的炎症介质,并且在许多疾病中发挥着重要作用.近年来,很多学者致力于5 LOX的研究,从而为5-LOX抑制剂的研发提供理论依据.本文对5-LOX的分子结构、细胞内定位、表达与活性调控及其抑制剂的研究进展进行综述.     

植物脂氧合酶蛋白特性及其在果实成熟衰老和逆境胁迫中的作用

脂氧合酶（lipoxygenase,LOx）作为植物脂肪酸氧化途径的关键酶,是多基因家族,在植物生长发育中起重要作用。本文综述了脂氧合酶的蛋白结构特征、催化反应的位置特异性、分类及其代谢途径,重点介绍了LOX代谢途径中的氢过氧化物裂解酶（hydropemxide lyase,HPL）支路和丙二烯氧化物合酶（allene oxide synthase,AOS）支路,最后阐述了LOxs在植物成熟衰老和逆境胁迫中的作用,为通过基因工程手段改善果实品质以及提高植物抗逆性提供了一定的理论依据。     

蚕豆叶片几丁质酶活性的蚜虫诱导──植物生理应激反应的趋同性

在蚜虫和蚕豆构成的种群作用系统中,证实蚜虫的取食危害能诱导植物几丁质酶活性的增加,并且诱导反应的强度与昆虫危害程度相关．实验结果表明,诱导效应能在植物体内传导,诱导反应随时间呈动态变化．综合目前几丁质酶的诱导研究,认为几丁质酶不是特异性的抗性蛋白,而是应激反应的伴随产物,并提出在逆境条件下植物的应激反应模式．     

Herbivory and seedling performance in a fragmented temperate forest of Chile

Forest fragmentation alters plant-animal interactions, including herbivory. Relying manipulative experiments, we test if the reduction in insect herbivory associated with forest fragmentation translates into increased seedling growth and survival of three tree common species (Aristotelia chilensis, Cryptocarya alba and Persea lingue) in forest fragments and continuous forests in coastal Maulino forest, central Chile. Furthermore, we test if after protecting seedlings from herbivorous insects, plant performance is increased regardless of forest fragmentation. Nursery grown seedlings were transplanted into four forest fragments and a continuous forest during 2002. Insects, important herbivores in this forest, were excluded from half the seedlings by repeated applications of insecticides. Compared to continuous forests, in forest fragments, herbivory was reduced in all three species, seedling growth was greater in A. chilensis and C. alba but not in P. lingue, and survivorship was unaffected by herbivory or fragmentation in all three species. Protecting seedlings from insects reduced herbivory in the continuous forest to similar levels attained in the forest fragments. No change in herbivory results from by protecting seedlings in forest fragments. These results confirm that insects are important herbivores in the Maulino forest and also support the hypothesis that fragmentation can have strong indirect effects on plant communities as mediated through trophic interactions.     

Effect of Acinetobacter sp on metalaxyl degradation and metabolite profile of potato seedlings (Solanum tuberosum L.) alpha variety

One of the most serious diseases in potato cultivars is caused by the pathogen Phytophthora infestans, which affects leaves, stems and tubers. Metalaxyl is a fungicide that protects potato plants from Phytophthora infestans. In Mexico, farmers apply metalaxyl 35 times during the cycle of potato production and the last application is typically 15 days before harvest. There are no records related to the presence of metalaxyl in potato tubers in Mexico. In the present study, we evaluated the effect of Acinetobacter sp on metalaxyl degradation in potato seedlings. The effect of bacteria and metalaxyl on the growth of potato seedlings was also evaluated. A metabolite profile analysis was conducted to determine potential molecular biomarkers produced by potato seedlings in the presence of Acinetobacter sp and metalaxyl. Metalaxyl did not affect the growth of potato seedlings. However, Acinetobacter sp strongly affected the growth of inoculated seedlings, as confirmed by plant length and plant fresh weights which were lower in inoculated potato seedlings (40% and 27%, respectively) compared to the controls. Acinetobacter sp also affected root formation. Inoculated potato seedlings showed a decrease in root formation compared to the controls. LC-MS/MS analysis of metalaxyl residues in potato seedlings suggests that Acinetobacter sp did not degrade metalaxyl. GC-TOF-MS platform was used in metabolic profiling studies. Statistical data analysis and metabolic pathway analysis allowed suggesting the alteration of metabolic pathways by both Acinetobacter sp infection and metalaxyl treatment. Several hundred metabolites were detected, 137 metabolites were identified and 15 metabolic markers were suggested based on statistical change significance found with PLS-DA analysis. These results are important for better understanding the interactions of putative endophytic bacteria and pesticides on plants and their possible effects on plant metabolism.     

辽宁铁岭榛白粉病病原菌研究

榛是辽宁铁岭市最重要的木本经济树种。白粉病是榛生产中的主要病害,导致树体衰弱,减少花芽分化,落果,降低产量。本研究对该病害的发生和危害进行了调查,通过病原菌形态学和rDNA ITS序列分析,确定该病害的病原菌为榛白粉菌(Erysiphe corylacearum)。     

Gibberellin is required for the formation of tension wood and stem gravitropism in Acacia mangium seedlings

Background and Aims Angiosperm trees generally form tension wood on the upper sides of leaning stems. The formation of tension wood is an important response to gravitational stimulus. Gibberellin appears to be involved in the differentiation of secondary xylem, but it remains unclear whether gibberellin plays a key role in the formation of tension wood and plant gravitropism. Therefore, a study was designed to investigate the effects of gibberellin and of inhibitors of the synthesis of gibberellin, namely paclobutrazole and uniconazole-P, on the formation of tension wood and negative stem gravitropism in Acacia mangium seedlings. Methods Gibberellic acid (GA(3)), paclobutrazole and uniconazole-P were applied to seedlings via the soil in which they were growing. Distilled water was applied similarly as a control. Three days after such treatment, seedlings were tilted at an angle of 45° from the vertical, and samples of stems were collected for analysis 2 weeks, 2 months and 6 months after tilting. The effects of treatments on the stem recovery degree (Ro) were analysed as an index of the negative gravitropism of seedlings, together the width of the region of tension wood in the upper part of inclined stems. Key Results It was found that GA(3) stimulated the negative gravitropism of tilted seedling stems of A. mangium, while paclobutrazole and uniconazole-P inhibited recovery to vertical growth. Moreover, GA(3) stimulated the formation of tension wood in tilted A. mangium seedlings, while paclobutrazole and uniconazole-P strongly suppressed the formation of tension wood, as assessed 2 weeks after tilting. Conclusions The results suggest that gibberellin plays an important role at the initial stages of formation of tension wood and in stem gravitropism in A. mangium seedlings in response to a gravitational stimulus.     

Evaluation of potential biocontrol rhizobacteria from different host plants of Verticillium dahliae Kleb

AIMS: A screening approach was developed to assess the potential of rhizobacterial strains to control Verticillium wilt caused by Verticillium dahliae Kleb. METHODS AND RESULTS: Sixty randomly chosen antagonistic bacterial strains originally isolated from rhizosphere of three different host plants of V. dahliae--strawberry, potato and oilseed rape--were evaluated for biocontrol and plant growth promotion by analysing in vitro antagonism towards V. dahliae and other plant pathogenic fungi, production of fungal cell wall-degrading enzymes and plant growth-promoting effects on strawberry seedlings. To test the plant growth-promoting effect, a microplate assay with strawberry seedlings was developed. Although the rhizobacterial strains were isolated from different plants they showed effects on the growth of strawberry seedlings. According to the in vitro biocontrol and plant growth-promoting activity, the three best candidates Pseudomonas putida B E2 (strawberry rhizosphere), Ps. chlororaphis K15 (potato rhizosphere) and Serratia plymuthica R12 (oilseed rape rhizosphere) were selected for greenhouse experiments to verify the in vitro screening results. Under greenhouse conditions the isolates selected according to this strategy were as effective, or more effective than commercial biocontrol agents and may therefore possibly be valuable as antagonists of V. dahliae. CONCLUSIONS: In this study, the screening strategy resulted in a selection of three interesting biocontrol candidates against Verticillium: Ps. putida B E2 (strawberry rhizosphere), Ps. chlororaphis K15 (potato rhizosphere) and Ser. plymuthica R12 (oilseed rape rhizosphere). SIGNIFICANCE AND IMPACT OF THE STUDY: A new combination of in vitro screening methods including a microplate assay with strawberry seedlings to test the plant growth promoting effect which allow to more efficiently select potential biological control agents was developed successfully.     

不同土壤硒水平对白术幼苗生长及部分生理特性的影响

硒(Se)为植物非必需营养元素,但适量的硒对植物生长发育具有促进作用,因此研究植物生长对硒的响应及其生理机制具有重要意义。该研究采用盆栽试验,设置6种不同的土壤硒处理(0、5、10、25、50、100 mg·kg^-1),观察不同硒处理对白术幼苗生理生长的影响及其综合效应。结果表明：(1)相比于对照处理,5 mg·kg^-1的硒处理可以提高白术幼苗鲜重、叶片叶绿素相对含量(SPAD值)以及可溶性糖(SS)含量,增幅分别为8.8%、8.4%和60.3%;显著降低白术幼苗叶片的过氧化物酶(POD)和过氧化氢酶(CAT)活性;同时减少叶片可溶性蛋白(SP)和丙二醛(MDA)含量,降幅分别为32.1%和18.9%。(2)25 mg·kg^-1以上硒处理则不利于白术幼苗的生长,会导致MDA和超氧阴离子自由基(·O₂^-)含量显著上升,使白术幼苗的抗氧化系统遭受胁迫。(3)主成分分析表明,鲜重、株高、叶片SP含量、CAT和POD活性等可作为反映白术幼苗生理生长的重要特征指标。综上表明,土施适量硒可...     

光照条件对蒙古栎幼苗生长及形态特征的影响

对生长于不同光照环境(林内和林外)下的蒙古栎幼苗的形态特征进行了比较.结果表明,光照条件对蒙古栎幼苗的生物量及其分配具有明显影响,林外幼苗单株生物量为林外的4.48倍,其中以根系生物量的差别为最大,林外为林内的6.23倍;林外与林内幼苗根冠比分别为2.70和1.11.在不同的光照条件下,蒙古栎幼苗的叶片形态表现出明显不同,林外叶片比叶面积明显低于林内,分别为139.55cm2/g 和284.94cm2/g,林内约为林外的2.04倍;一次生长叶面积林外明显低于林内,总叶面积则高于林内.二次生长使蒙古栎幼苗的叶面积有明显增加,但是经过二次生长后,幼苗的单株生物量没有明显增加,说明二次生长叶片对于蒙古栎幼苗生物量的积累没有明显贡献;光照对于蒙古栎主干及根系的形态具有明显影响,林外幼苗高(包括二次生长)明显低于林内幼苗,而地径则相反,林外幼苗根系的长度和直径则明显高于林内幼苗;林外幼苗顶芽体积明显大于林内幼苗.同时,林外幼苗的二次生长导致顶芽体积明显下降,从而对翌年的高生长量和未来干型产生影响.认为,蒙古栎幼苗通过形态上的一系列可塑性变化来适应不同的光环境以获取最大的碳收益.     

广东松幼苗存活率和生长特征的初步研究

2006年5月至2008年7月,在南岭国家级自然保护区测定了不同年龄、不同种植方式的广东松(Pinus kwangtungensis)幼苗的存活率、株高和基径等指标,以期为国家保护植物广东松的保育提供资料。结果表明,实验期间袋栽苗存活率下降明显,从开始时的100%下降到结束时的50%;裸植苗与移植苗的存活率从100%下降到80%左右。总月均株高、基径的增量,袋栽苗、裸植苗、移植苗依次为1.01、1.39、2.76cm;0.17、0.20、0.64mm。年均株高、基径增值,移植苗、裸植苗、移植苗依次为32.91、17.22、12.77cm;7.64、2.31、2.0mm。随着年龄的增长,各组幼苗的株高和基径增长均加快,株高与基径之间存在着极显著的线性相关关系,广东松幼苗至10a生仍属快速生长期。     

In vitro plant regeneration from seedling-derived explants of ramie [Boehmeria nivea (L.) Gaud]

Ramie [Boehmeria nivea (L.) Gaud] is one of the most important perennial fiber crops in China. In vitro tissue culture of ramie could serve as an important means for its improvement through genetic transformation. To improve the regeneration capacity of ramie, the effects on plant regeneration of donor plant age, basal medium, plant growth regulators, and culture conditions were evaluated using explants derived from the cotyledon, hypocotyl, leaf, petiole, and stem of ramie seedlings. Cotyledons and hypocotyls excised from 4-d-old seedlings and leaves and petioles and stems from 15-d-old seedlings were optimal explants. The highest regeneration efficiency was obtained on Murashige and Skoog salts with Gamborg’s B₅ vitamins basal medium containing 2.27 μM thidiazuron (TDZ) and 0.054 μM naphthaleneacetic acid (NAA) for the five explant types tested. A photoperiod of 16:8 h (light/dark) was found to be superior than continuous darkness for regeneration of ramie using TDZ. The regenerated shoots were transferred to hormone-free medium for shoot elongation and successfully rooted on half-strength Murashige and Skoog supplemented with 0.134 μM NAA. The rooted plantlets with four to five leaves were transplanted to greenhouse for further growth.     

模拟增雨对荒漠植物幼苗生长和根系形态的影响

降雨是荒漠生态系统过程和功能的最重要限制因子,荒漠植物幼苗对生长季降雨的变化极端敏感。为探讨荒漠植物对未来降雨格局变化的响应,选取乌兰布和沙漠两种典型荒漠植物幼苗(白刺和油蒿)为研究对象,根据生长季内(6—9月)每次降雨量,进行不同梯度的人工模拟增雨试验(CK:自然降雨、A:增雨25%、B:增雨50%、C:增雨75%、D:增雨100%),研究两种植物幼苗生长和根系形态特征对降雨量变化的响应。结果表明:(1)不同增雨处理对白刺和油蒿幼苗的地上部生长有显著影响(P<0.05),增雨处理的白刺和油蒿幼苗的株高、平均冠幅和基径显著高于CK,并随着增雨量的增大而增大(白刺基径除外);(2)增雨处理之间、白刺和油蒿之间在总根长、总表面积、平均直径、总体积、根尖数和分叉数均有显著差异(P<0.05)。对白刺幼苗而言,B处理和C处理的根系参数均显著大于CK、A和D处理,且B和C处理之间没有显著差异(平均直径除外);对油蒿幼苗而言,随着增雨量的增加,油蒿总根长、总表面积、总体积、根尖数和分叉数呈现逐渐增加的趋势,而平均直径呈现先增加后降低的趋势,且在B处理下达到最大值。(3)增雨处理显著降低...