2,4-二硝基苯酚对采后龙眼果皮脂氧合酶活性和膜脂脂肪酸组分的影响

以'福眼'龙眼(Dimocarpus longan Lour.'Fuyan')果实为材料,研究呼吸解偶联剂2,4-二硝基苯酚(DNP)对采后果皮脂氧合酶(LOX)活性、膜脂脂肪酸组分和细胞膜透性的影响及其与果皮褐变的关系.结果表明:DNP处理导致龙眼果皮细胞膜透性、LOX活性和褐变指数增加,膜脂脂肪酸组分中的棕榈酸(C16:0)、硬脂酸(C18:0)等饱和 脂肪酸的组分增加,亚油酸(C18:2)、亚麻酸(C18:3)和花生一烯酸(C20:1)等不饱和脂肪酸的组分下降,脂肪酸不饱和指数和脂肪酸不饱和度下降.因此认为,DNP促进了龙眼果实果皮褐变可能是由于提高了LOX活性,促进了膜脂不饱和脂肪酸的降解而引起膜系统完整性受损,最终导致细胞膜结构的破坏,使酚酶与酚类物质接触而引起酚类物质氧化的结果.     

茉莉酸甲酯对茶条槭悬浮细胞没食子酸合成的影响

为了研究茶条槭悬浮细胞中没食子酸的合成,该研究进行了茉莉酸甲酯诱导试验。通过添加茉莉酸甲酯,利用HPLC检测诱导后细胞中没食子酸的含量变化情况,同时利用电导仪、酸度计、分光光度计法和激光共聚焦显微镜对培养液和细胞进行电导率、pH值、苯丙氨酸解氨酶(PAL)活性以及细胞形态等进行分析。结果表明:(1)相对于正常培养的细胞,添加100μmol·L~(-1)的茉莉酸甲酯诱导24 h时,没食子酸的含量达到最高为12.49 mg·g~(-1),其含量是对照的2倍左右。(2)茉莉酸甲酯的添加导致细胞培养液的pH值和电导率成波动趋势,细胞膜受损,通透性增大,细胞核分散,出现多个细胞核现象。(3)细胞内可溶性蛋白含量在诱导24 h、72 h和5 d时达到高峰,其含量分别是对照的1.4、1.67、2.07倍左右。(4)苯丙氨酸解氨酶活性在诱导24 h和5 d时分别出现一次高峰,其活性分别是对照的2倍和3.75倍。研究认为,茉莉酸甲酯处理短时间内促进了茶条槭细胞内没食子酸含量的积累,细胞内PAL活性和可溶性蛋白含量有所增加,对细胞液中的pH值和电导率影响不显著。     

ABA信号通路对葡萄果皮花青苷生物合成的调控机制研究

以'红巴拉多'葡萄为试验材料,在转色前期(约花后6周)用300 mg/L的ABA对果穗进行处理,以清水处理为对照;测定不同发育时期葡萄果实的单果重、可滴定酸、可溶性固性物等生理指标,同时测定果皮中总花青苷及ABA含量;检测不同发育时期果皮中ABA信号通路和花青苷生物合成相关基因表达量,克隆6个与花青苷生物合成相关基因的...     

拟茎点霉侵染对采后龙眼果皮LOX活性和膜脂脂肪酸组分的影响

用拟茎点霉(Phomopsis longanae Chi)侵染福眼龙眼(Dimocarpus longan Lour. ‘Fuyan’)果实,研究龙眼果皮脂氧合酶(LOX)活性、膜脂脂肪酸组分和细胞膜透性的变化及其与果皮褐变的关系。结果表明：拟茎点霉侵染导致龙眼果皮褐变指数、LOX活性和细胞膜透性增加,不饱和脂肪酸组分[亚油酸(C18∶2)、亚麻酸(C18∶3)和花生一烯酸(C20∶1)]下降而饱和脂肪酸组分[棕榈酸(C16∶0)和硬脂酸(C18∶0)]增加,脂肪酸不饱和指数(IUFA)和脂肪酸不饱和度下降。拟茎点霉侵染提高龙眼果皮LOX活性和加速膜脂不饱和脂肪酸的降解,从而破坏细胞膜系统的完整性,导致膜系统区室化功能丧失,使多酚氧化酶与酚类物质接触,引起酚类物质的酶促氧化和黑褐色高聚物形成,导致龙眼果皮褐变。     

不同诱导处理对番茄叶片营养物质含量及防御酶活性的影响

本文研究了番茄在不同时间下受西花蓟马Frankliniella occidentalis危害(DTF)、机械损伤(MW)、茉莉酸(JA)和水杨酸甲酯(MeSA)外源诱导后,叶片营养物质含量和防御酶活性的变化。结果表明:各种诱导处理24 h和36 h时,番茄叶片可溶性蛋白和可溶性糖含量不同程度的下降,其中虫害处理36 h时,叶片可溶性蛋白和可溶性糖含量下降最明显;在48 h时除水杨酸甲酯处理外,番茄营养物质含量均显著升高。β-1,3葡聚糖酶(PR-2)活性在虫害、机械损伤和茉莉酸处理24 h和36 h后均升高,其中虫害处理的PR-2活性最高。各种处理均能诱导番茄叶片苯丙氨酸解氨酶(PAL)活性明显升高,且均随时间的延长持续升高。所有处理24 h时的番茄叶片多酚氧化酶(PPO)均被激发。各种处理均能导致植株的脂氧合酶(LOX)活性升高,但不同处理诱导的LOX活性升高的时间不同。结果表明,番茄能通过改变营养物质含量和防御酶活性对不同诱导处理作出生理应激反应,但反应程度与诱导方式和时间有关。     

脂氧合酶在诱导红豆杉细胞产紫杉醇中的作用

对红豆杉悬浮培养细胞中脂氧合酶(LOX)在诱导子诱导紫杉醇合成中的作用进行了探讨。结果表明真菌诱导子处理可提高细胞内LOX的活性和紫杉醇的产量,而诱导前用LOX抑制剂菲尼酮处理,可完全抑制诱导子对LOX活性和紫杉醇合成的诱导作用。说明LOX途径可能参与了紫杉醇的合成过程。外加茉莉酸甲酯也可激活LOX活性和紫杉醇合成,诱导前用菲尼酮处理可抑制诱导子诱导的LOX活性和紫杉醇合成,说明外源茉莉酸甲酯可能是通过激活细胞内LOX途径而启动下游紫杉醇的合成。为了进一步研究脂氧合酶在紫杉醇合成中的作用。我们还对红豆杉细胞脂氧合酶的分布和分子量等性质进行了研究。     

茉莉酸诱导桑枝对桑天牛卵啮小蜂的引诱作用及桑枝挥发物组分分析

【目的】探讨茉莉酸诱导的桑树Morus alba枝挥发物对桑天牛卵啮小蜂Aprostocetus prolixus趋性行为的影响,研究桑枝挥发物的动态变化规律,为揭示茉莉酸诱导桑枝产生的间接抗虫作用机理提供理论依据。【方法】本试验利用嗅觉测定仪,研究了不同浓度茉莉酸处理24,48和72 h后的桑枝对桑天牛卵啮小蜂的引诱作用,并采用气相色谱-质谱联用仪(GC/MS)对茉莉酸(1 000μmol/L)处理不同时间后的桑枝挥发物组分进行了分析。【结果】在10μmol/L茉莉酸处理后的不同时间内,桑枝对桑天牛卵啮小蜂均未表现出明显的引诱作用;当茉莉酸浓度为100μmol/L时,桑枝仅在处理48 h后对桑天牛卵啮小蜂具有显著的引诱活性;然而,经1 000μmol/L茉莉酸处理24 h和48h后,桑枝对桑天牛卵啮小蜂的引诱活性明显高于对照(24 h,P0.05;48 h,P0.01),72 h后桑枝的引诱作用消失。Spearman等级相关性分析表明,茉莉酸浓度与桑枝对桑天牛卵啮小蜂的引诱百分率显著正相关(ρ=0.791,P=0.006)。茉莉酸(1 000μmol/L)处理桑枝挥发物组分包括醇类、酯类、萜类物质、芳香族化合物和含氮化合物,其中萜类物质种类最多(13种)。随着处理时间的变化,桑枝挥发物组分及总释放速率也随之发生改变。处理24 h后,桑枝释放出18种组分,比对照多11种组分,其总释放速率也明显提高,为对照的8.2倍;48 h后桑枝释放出22种组分,比对照多15种组分,其总释放速率进一步提高,为对照的44.6倍;72 h后桑枝释放出13种组分,比对照多6种组分,其总释放速率大幅降低,为对照的3.9倍,但与对照无显著差异。【结论】随着茉莉酸浓度的提高,桑枝对桑天牛卵啮小蜂的引诱活性逐渐增强。茉莉酸能诱导桑枝挥发物的大量释放及新组分的产生。     

外源茉莉酸甲酯对辣椒烟粉虱的影响

化学农药仍是目前蔬菜烟粉虱Bemisia tabaci防控的重要措施,研发有效的非化学措施防控烟粉虱是蔬菜绿色生产亟待解决的问题。本文以苏椒15号（感性品种）和新苏椒五号（抗性品种）辣椒Capsicum annuum L.为对象,通过在辣椒上喷施茉莉酸甲酯,研究外源茉莉酸甲酯对烟粉虱发育历期、存活率、消化酶活性和田间烟粉虱种群动态的影响。研究发现,取食茉莉酸甲酯处理的辣椒后烟粉虱的发育历期显著延长、存活率明显下降。其中取食感性品种辣椒和抗性品种辣椒的烟粉虱发育历期分别延长7.66 d和9.66 d,存活率分别下降10.5%和9.89%;取食感性品种辣椒的烟粉虱主要是延长卵期、4龄若虫期和伪蛹期,而取食抗性品种辣椒的烟粉虱各历期均延长。外源茉莉酸甲酯对烟粉虱体内消化酶的活性也有明显的影响,取食茉莉酸甲酯处理的辣椒后烟粉虱的消化酶活性显著下降,取食感性品种辣椒和抗性品种辣椒24 h后,胰蛋白酶活力分别较对照下降了61.86%和45.0%,糜蛋白酶活性分别较对照下降了47.29%和40.11%。大田辣椒上喷施茉莉酸甲酯后,烟粉虱的种群数量迅速下降,但在抗性品种和感性品种上烟粉虱的校正虫口减退率没有明显的差异。研究发现,外源茉莉酸甲酯处理,可以延缓烟粉虱的发育速率,降低胰蛋白酶和糜蛋白酶的活性,对田间烟粉虱种群也有较好的控制作用。     

茄二十八星瓢虫为害对不同基因型番茄叶内三种抗性酶活性的影响

【目的】研究茉莉酸合成相关基因在番茄抗茄二十八星瓢虫Henosepilachna vigintioctopunctata Fabricius中的作用,探讨茉莉酸信号因子在植物防御过程中起到的作用。【方法】利用3种基因型番茄茉莉酸合成缺失突变体spr2、茉莉酸合成过量表达体35s、野生型番茄Wt为材料,通过经2龄茄二十八星瓢虫分别取食6、24、48 h后,利用分光光度计测定3种基因型番茄叶片内苯丙氨酸解氨酶(Phenylalanineammonialyase,PAL)、胰蛋白酶抑制剂(Protease inhibitors,PI)和脂氧合酶(Lipoxygenase,LOX)酶活性的动态变化。【结果】35s型番茄叶片内PI活性显著高于另两种番茄叶片,而spr2型番茄叶片PI活性最低。瓢虫为害后,3种基因型番茄PI酶活性明显提高,在35s和Wt型番茄中,PI和LOX酶活性在胁迫24 h和6 h达到最高值,而spr2型番茄没有显著变化。受到瓢虫侵染的系统叶中,PI和LOX酶活性也受到了诱导,系统叶变化趋势同危害叶相同,但诱导的PI和LOX酶活性明显低于危害叶。在危害处理过程中,均呈现上升-下降的趋势,在系统叶中,则PAL活性没有显著变化。番茄叶片受害后,PI和LOX酶活性上升辐度大于PAL,说明PI和LOX对取食胁迫响应比PAL更敏感。【结论】35s茉莉酸合成过量表达体的番茄对茄二十八星瓢虫有一定的抗虫作用,因此,茉莉酸在植物抗性中起了一定作用。     

外源茉莉酸甲酯对干旱胁迫下狭叶黄芩光合和生理特性的影响

以狭叶黄芩为试验材料,测定了不同浓度(0.1、0.5、1、2 mmol·L^-1)茉莉酸甲酯对干旱胁迫下(15%,PEG-6000)狭叶黄芩表型特征、光合以及生理特性的影响。结果外源施加茉莉酸甲酯增强了狭叶黄芩的净光合速率、气孔导度和蒸腾速率。有效降低了狭叶黄芩受伤害等级。可以有效缓解降低了胞间CO2浓度,其中施用2 mmol·L^-1茉莉酸甲酯9 d后对狭叶黄芩的净光合速率、蒸腾速率、气孔导度、胞间CO2浓度的影响最为显著。处理组的游离脯氨酸含量低于CK。可溶性蛋白含量在前6 d的处理中低于CK,而在6 d以后的处理中显著高于CK。外源施加茉莉酸甲酯能够提高SOD、POD、CAT活性。对狭叶黄芩的光合参数和生理指标的研究结果表明,经外源施加的茉莉酸甲酯处理能够有效减缓干旱胁迫对狭叶黄芩的不良影响。     

Dual positional specificity and expression of non-traditional lipoxygenase induced by wounding and methyl jasmonate in maize seedlings

Lipoxygenases (LOXs) catalyze the formation of fatty acid hydroperoxides involved in responses to stresses. This study examines the expression of a non-traditional dual positional specific maize LOX in response to wounding or methyl jasmonate (MeJA). Full-length maize LOX cDNA was expressed in Escherichia coli, and recombinant LOX was purified and characterized enzymatically. RP-HPLC and GC-MS analysis showed that the purified LOX converts alpha-linolenic acid into 13-hydroperoxylinolenic acid and 9-hydroperoxylinolenic acid in a 6:4 ratio. LOX mRNA accumulated rapidly and transiently in response to wounding reaching a peak of expression about 3 h after wounding. This increase followed an initial increase in endogenous jasmonic acid (JA) 1 h after wounding (JA burst). However, the expression of LOX induced by MeJA lasted longer than the expression induced by wounding, and the MeJA-induced expression seemed to be biphasic pattern composed of early and late phases. The expression of LOX in the presence of inhibitors of JA biosynthesis was not completely inhibited, but delayed in wound response and the expression period was shortened in MeJA response. These results suggest that wound-responsive JA burst may trigger the early phase of LOX expression which facilitates biosynthesis of endogenous JA through its 13-LOX activity, and subsequently leads to the activation of the late phase LOX expression in MeJA-treated maize seedlings. Implications of dual positional specificity of maize LOX in the observed expression kinetics are discussed.     

Characterization, induction by wounding and salicylic acid, and activity against Botrytis cinerea of chitinases and β‐1,3‐glucanases of ripening grape berries

In order to better understand the defense strategy of grape berries ( Vitis vinifera L. cv. Pinot noir) as they mature, the activities of the defense‐related proteins, chitinase (CHV, EC 3.2.1.14) and β‐1,3‐glucanase (laminarinase, EC 3.2.1.39) were first estimated in berries at different maturation stages. Chitinase levels rose proportionally to the berry reducing sugar content, an indicator of the berry ripening degree, up to values 10 times higher than the ones seen in resting grapevine leaves. This rise in activity was due to the accumulation of two isoforms, CHV 5 and CHV 11. One more chitinase isoform, CHV 12, appeared in senescent berries. Conversely, no glucanase activity could be detected in berries at any maturation stage. Accumulation of chitinases and (β‐1,3‐glucanases could be stimulated by wounding the berry peduncle. Adding salicylic acid to the wounded berries only potentiated the wounding effect on the berry chitinase activity. The most active chitinase isoform, CHV 5, was purified to homogeneity. It represented about 40% of the total extractable protein content of a ripe berry. Its molecular mass was estimated to be 31 kDa. The peptide sequencing of four of its tryptic fragments revealed strong homologies to several class IV chitinases. Finally, it was shown to inhibit the germination of conidia of Botrytis cinerea by 50% at a concentration of 7.5 µg ml⁻¹.     

镉胁迫对平邑甜茶脂肪酸构成及脂质过氧化的影响

以平邑甜茶幼苗为试材,研究了镉胁迫下幼苗叶片和根系膜脂肪酸构成、活性氧、脂氧合酶和丙二醛含量的变化.结果表明：氯化镉处理后7～12 h,脂肪酸种类及其相对含量变化最为明显.处理后7 h,叶片和根系脂肪酸不饱和水平升至最高,含量分别达8282%和7243%;叶片可检测到的脂肪酸在处理后12 h由11种增至14种,根系则在处理17 h后由4种增至6种.O₂^.-产生速率在处理3 h、H₂O₂含量在处理7 h时升至最高,丙二醛含量和脂氧合酶活性则随着处理时间的延长逐渐增加.镉胁迫通过诱导活性氧和脂氧合酶来改变平邑甜茶脂肪酸构成,并引起脂质过氧化;镉处理12 h前,脂质过氧化是活性氧和脂氧合酶的共同结果;但处理12 h后,脂质过氧化加剧主要在于脂氧合酶活性的持续增加.     

蓟马取食、机械损伤以及外源水杨酸甲酯和茉莉酸对菜豆叶片防御酶活性的影响

【目的】探讨菜豆对昆虫取食防御反应的生化机制。【方法】研究了西花蓟马Frankliniella occidentalis取食、机械损伤以及外源水杨酸甲酯（MeSA）和茉莉酸（JA）处理后菜豆叶片防御酶活性的变化。【结果】西花蓟马取食、机械损伤及MeSA和JA处理均能明显提高过氧化物酶（POD）的活性,前2种处理POD活性在72 h上升到最高峰,而后2种处理则在48 h达到最高峰。蛋白酶抑制剂（PI）活性在西花蓟马取食后升高最明显。JA途径关键酶脂氧合酶（LOX）和多酚氧化酶（PPO）的活性在西花蓟马取食、机械损伤和JA诱导处理均升高,但外源MeSA诱导处理则不能诱导它们的活性(P>0.05)。SA途径的关键酶苯丙氨酸解氨酶（PAL）在西花蓟马取食和机械损伤后均有一个先升高后下降的过程,外源MeSA诱导只在24 h引起PAL活性升高,其余时间下和对照没有明显的区别,外源JA诱导未能引起PAL活性的显著变化(P>0.05)。西花蓟马取食、JA和MeSA诱导以及机械损伤均能诱导β-1,3 葡聚糖酶（PR-2）活性上升(P<0.05)。【结论】结果说明,不同处理可诱导菜豆植株产生明显的防御反应,但酶活性的变化与处理方式和处理时间有关。     

Early physiological and cytological events induced by wounding in potato tuber

The response of potato tuber (Solanum tuberosum L. cv. Kennebec) to mechanical wounding was investigated at different times. Changes in the levels of indole-3-acetic acid (IAA), polyunsaturated fatty acids (PUFAs) and lipid hydroperoxides (LOOHs) were monitored up to 120 min after wounding and related to the cytological events occurring up to 24 h. Twenty minutes after injury, an increase in IAA and LOOH levels and a decrease in the levels of PUFAs was observed. Wounding induced mitoses in differentiated (parenchyma) cells starting at 120 min, and promoted an increase of mitotic activity in the meristematic cells (procambium and bud dome), after 360 min. The inhibition of the increase in LOOHs and IAA by lipoxygenase (LOX) inhibitors, as well as the ability of in vitro peroxidated linoleic acid to enhance IAA production, suggest a close relationship among lipoperoxidation, IAA and mitotic activity in the response of potato tuber cells to injury, resulting in a specific growth response, i.e. bud growth and periderm formation.     

葡萄贮藏过程中落粒与离区酶活性变化及植物生长调节物质的关系

研究了无核白葡萄(Vitis vinifera L.)采后贮藏过程中离区纤维素酶、果胶酯酶(Pectinesterase,PE)、多聚半乳糖醛酸酶(polygalacturonase,PG)、脂氧合酶(lipoxygenase,LOX)和过氧化物酶(peroxidase,POD)活性的变化与落粒的关系及植物生长调节物质对其的影响。结果表明,葡萄在贮藏过程中,伴随浆果落粒的增加,离区纤维素酶、PG、LOX、POD活性升高,PE活性下降。离区纤维素酶、PG、LOX等酶的活性与葡萄落粒程度之间呈显著正相关。外源ABA和CEPA处理能增强离区纤维素酶、PG、LOX活性,促进落粒;GA3,IAA处理则能抑制离区纤维素酶、PG、LOX活性,减轻落粒。ABA对落粒的促进效应及GA3对纤维素酶活性和落粒的抑制效应尤为明显,表明GA3与ABA比值在葡萄采后落粒过程中起重要的作用。     

Effects of Water-Deficit Irrigation on Hormonal Content and Nitrogen Compounds in Developing Berries of Vitis vinifera L. cv. Tempranillo

Water-deficit irrigation to grapevines reduces plant growth, yield, and berry growth, altering the ripening process, all of which may influence fruit composition and wine quality. Therefore, the goals of this study were (1) to investigate the influence of the main endogenous berry hormones, abscisic acid (ABA), indole-3-acetic acid (IAA), salicylic acid (SA), and jasmonic acid (JA), on berry growth and ripening under water-deficit conditions and (2) to analyze changes in fruit composition, specifically N compounds, under water deprivation. The study was carried out using container-grown Tempranillo grapevines grown under controlled conditions in a greenhouse. Two irrigation treatments were imposed: control (well-watered) and sustained deficit irrigation (SDI). Water deficit decreased leaf area and the source-to-sink ratio, reduced yield and berry size, and decreased concentrations of the main phenolic compounds. SDI also modified berry hormonal status. At the pea-size stage, SDI berries had lower IAA and higher JA and SA than nonstressed berries. At veraison (onset of ripening), accumulation of ABA was less accentuated in SDI than in control berries. At harvest, the content of amino acids and free ammonium was low in both treatments but SDI-treated berries showed a significant accumulation of amines. Results suggest that water restrictions to grapevines might be playing a physiological role in reducing berry growth through affecting hormone dynamics, phenolic synthesis, and the berry amino acid content and composition, which could compromise fruit quality. Possible roles of endogenous IAA controlling berry size and endogenous ABA and SA controlling levels of anthocyanins and flavonols at harvest are discussed.     

Treatment of Grape Berries,a Nonclimacteric Fruit with a Synthetic Auxin,Retards Ripening and Alters the Expression of Developmentally Regulated Genes

Treatment of grape (Vitis vinifera L.) berries with the synthetic auxin-like compound benzothiazole-2-oxyacetic acid (BTOA) caused a delay in the onset of ripening of approximately 2 weeks. This was manifested as a retardation of the increases in berry weight, color, deformability, and hexose concentration. BTOA treatment also delayed by 2 weeks the increase in abscisic acid level that normally accompanies ripening and altered the expression of a number of developmentally regulated genes. A putative vacuolar invertase, which is normally expressed from berry set until ripening and turned off after ripening commences, remained expressed throughout development in BTOA-treated grape berries. This elevated expression resulted in increased levels of invertase activity. In contrast, the up-regulation of four other genes normally switched on at the time of ripening was delayed in BTOA-treated fruit. These included chalcone synthase and UDP-glucose-flavonoid 3-O-glucosyl transferase, both of which are involved in anthocyanin synthesis, a chitinase, and a ripening-related gene of an unknown function. These observations support the view that auxins (perhaps in conjunction with abscisic acid) may have a role in the control of grape berry ripening by affecting the expression of genes involved in the ripening process.