茶树品种及萎凋过程中叶片APX基因表达的qPCR分析

应用实时荧光定量聚合酶链式反应(qPCR)的方法对不同茶树品种及萎凋过程中抗坏血酸过氧化物酶(APX)基因的表达进行定量分析.结果表明:茶树不同品种APX基因的表达量存在显著差异,相对表达量变化范围为0.65 -5.69.6个茶树品种APX基因的相对表达量从大到小依次为毛蟹、福云6号、肉桂、福鼎大白茶、黄旦、铁观音;茶...     

施用硫肥和硒肥对茎瘤芥产量及抗氧化作用的影响

【目的】了解不同硫、硒肥施用量对茎瘤芥(Brassica juncea var.tumida)干物质量,硫、硒含量及叶片保护酶活性和代谢物质含量的影响,以探明茎瘤芥对硫、硒肥的生理响应机制。【方法】以茎瘤芥“涪杂1号”为供试品种,采用盆栽试验研究了硫(S) (0,50,100 mg/kg)、硒(Se) (0,1,3 mg/kg)不同用量处理组合(S₀Se₀(CK)、S₅₀Se₁、S₅₀Se₃、S₁₀₀Se₁、S₁₀₀Se₃)对茎瘤芥不同部位干物质量和硫、硒积累及叶片抗氧化能力的影响。【结果】与S₀Se₀相比,施用硫、硒肥能明显提高茎瘤芥根、膨大茎和叶片及单株干物质量。施用硫、硒的处理均能明显提高茎瘤芥各部位对硫、硒的吸收与积累,且硫和硒主要积累在茎瘤芥地上部分膨大茎和叶中。施用硫、硒的处理明显提高了各部位的有机硒和无机硒含量,其中膨大茎和叶中的有机硒含量明显高于无机硒;5个处理中,S₅₀Se₃处理根、膨大茎和叶中的有机硒与无机硒含量均最高。超氧化物歧化酶(SOD)活性以S₁₀₀Se₁处理最高,谷胱甘肽过氧化酶(GSH-Px)活性以S₅₀Se₃处理最高;而抗坏血酸过氧化酶(APX)和过氧化氢酶(CAT)活性随着硫、硒肥用量的增加变化不大。施用硫、硒肥后,茎瘤芥叶片中MDA含量较高,抗坏血酸（AsA）和过氧化氢（H₂O₂）含量较低。【结论】施用硫、硒肥能提高茎瘤芥单株干物质量,促进硒的吸收与积累,对SOD和GSHPx活性及MDA含量有明显影响。综合分析认为,50 mg/kg S+3 mg/kg Se是硫、硒肥施用的最佳组合。     

Induction of resistance in Yali pear (Pyrus bretschneideri Rehd.) fruit against postharvest diseases by acibenzolar-S-methyl sprays on trees during fruit growth

The objective of this work was to evaluate how disease resistance in harvested fruit of Yali pears (Pyrus bretschneideri Rehd.) may be affected by acibenzolar-S-methyl (ASM) sprays on trees. Results showed that disease incidence and lesion diameter in mature pears from trees sprayed with ASM for three times during growth and inoculated with Penicillium expansum or Alternaria alternata after harvest were 27.9 and 42.7%, or 29.1 and 23.4% lower, respectively, than in control fruit 17 days after inoculation. Mature fruit from ASM-treated trees exhibited higher activities of defense enzymes including phenylalanine ammonia-lyase (PAL), chitinase and β-1,3-glucanase than in control at harvest. In young pears, activities of peroxidase, polyphenoloxidase, PAL, chitinase and β-1,3-glucanase were significantly enhanced by ASM after first spray on trees. The ASM spray also significantly increased H₂O₂ level and glutathione reductase activity, but reduced activities of catalase and ascorbate peroxidase in young pears. The study indicated that enhancement of disease resistance in harvested Yali pear fruit could be the result of multiple effects of several factors related to plant defenses induced by ASM sprays on trees during fruit growth. Application of ASM in the field holds great promise for controlling postharvest diseases of the fruit.     

Menadione sodium bisulphite: a novel plant defence activator which enhances local and systemic resistance to infection by Leptosphaeria maculans in oilseed rape

Pretreatment of the first true leaves of oilseed rape plants ( Brassica napus cv. Bristol) with menadione sodium bisulphite (MSB) locally and systemically induced resistance, as shown by reduced lesion size and number, to infection by the fungal pathogen Leptosphaeria maculans , the causal agent of stem canker. Using a known systemic activator of salicylic acid-dependent PR-1 induction, acibenzolar- S -methyl (BTH; S -methylbenzo[1,2,3]thiadiazole-7-carbothiate) as a comparison, real-time PCR expression analysis of genes encoding a pathogenesis-related protein 1 ( PR-1 ) and an ascorbate peroxidase ( APX ) demonstrated a systemic enhancement of APX expression in MSB-pretreated plants, with no effect on PR-1 expression, suggesting augmented reactive oxygen species production in MSB-pretreated plants. The results demonstrate MSB to be an effective resistance activator in oilseed rape, and potentially useful for the control of stem canker.     

龙眼胚性愈伤组织胞浆型抗坏血酸过氧化物酶基因3''''末端序列的同源克隆

抗坏血酸过氧化物酶(ascorbate peroxidase,APX(EC1.11.1.11)),是活性氧清除的重要酶类。高等植物中的植物抗坏血酸存在多种同工酶,最大的区别在于叶绿体型和胞浆型,两者在酶学特性和核酸序列和分子机制上都有不同(Foy-er and Halliwell,1997)。至今,不少研究者进行APX各种同工     

Foliar application of chitosan activates artemisinin biosynthesis in Artemisia annua L.

There has been much interest in artemisinin owing to its excellent activity against malaria, an infectious disease threatening the tropical world. However, the low artemisinin content (0.01-0.8%, DW) in Artemisia annua, which is the only commercial source of artemisinin, makes artemisinin expensive to produce and not yet available on a global scale. Here we show that foliar application of 100 mg l⁻¹ chitosan improved artemisinin biosynthesis in A. annua. The content of dihydroartemisinic acid and artemisinin in chitosan-treated leaves increased by 72% and 53% compared with control values, respectively. Chitosan induced the expression of ADS and DBR2, which could explain the increase in level of artemisinic metabolites. After chitosan treatment, the amounts of hydrogen peroxide (H₂O₂) and superoxide anion (O₂⁻) in leaves of A. annua were 1.4 and 3.0 times higher than those of the control, respectively. Accumulation of reactive oxygen species (ROS) probably accelerated the conversion of dihydroartemisinic acid to artemisinin. Foliar application of 100 mg l⁻¹ chitosan had no harmful effect on A. annua growth. The simple method described here could be an effective method to improve artemisinin production in A. annua field cultivation.     

Administration of gulonolactone does not evoke ascorbic acid synthesis in teleost fish

Evidence is presented that for common carp (Cyprinus carpio L.), intraperitoneal injection of L-gulonolactone, a precursor of ascorbic acid synthesis in the D-glucuronic acid pathway, does not result in an increased concentration of ascorbate in tissue. Control fish injected with an equimolar amount of ascorbic acid have shown a significant increase in ascorbic acid concentration in the kidney, hepatopancreas, plasma and spleen. The ascorbate status in the carp body,i.e., the ascorbate nutritional history, produced significant differences in ascorbate withdrawal from circulation and probably in the catabolic rate. Acute fasting decreased ascorbate uptake into tissues as compared to fish fed a diet lacking ascorbate. Intraperitoneally injected ascorbate affects common carp being fed a diet containing 295 mg of total ascorbic acid kg^–1 by causing tissue to become saturated with vitamin C, similar to the tissues in the group undergoing acute fasting. There was no gulonolactone oxidase activity in the hepatopancreas of the common carp. These results suggest that the metabolic rate induced by feeding is the primary factor regulating ascorbate requirement.     

Overexpression of a Cytosolic Ascorbate Peroxidase Gene,OsAPX2, Increases Salt Tolerance in Transgenic Alfalfa

Alfalfa (Medicago sativa L.) is an important forage crop in the world and it is of great significance for the improvement of its salt tolerance. To improve salt tolerance in alfalfa, a rice ascorbate peroxidase gene (OsAPX2) was introduced into alfalfa using Agrobacterium tumefaciens-mediated transformation with marker gene bar. The different T-DNA insertions in T₁ transgenic alfalfa were identified by Southern hybridization. Three independent T₂ transgenic lines were selected for stress analysis and the results showed that all of them were salt tolerant compared with wild-type plants. The transgenic plants had low levels of H₂O₂, malondialdehyde and relative electrical conductivity under salt and drought stresses. Moreover, the contents of chlorophyll and proline, and APX activity were high in transgenic plants under salt and drought stresses. Taken together, the overexpression of OsAPX2 enhances salt tolerance in alfalfa through scavenging reactive oxygen species.     

植物细胞质APX1的研究进展

活性氧(ROS)在植物生长发育和对各种逆境适应过程中扮演双面角色：高浓度下引起氧化损伤、低浓度下发挥第二信使作用,其角色转换取决于其产生和清除之间的平衡状态,并严格受控于体内一套由酶和非酶组分构成的双元抗氧化系统。在抗氧化酶类中,位居细胞质的抗坏血酸过氧化物酶1(APX1)在胞内氧化还原态水平调控中起到关键作用,在ROS清除网络中居于核心地位,已被视作ROS功能的重要杠杆,并因而获得相对最广泛的研究关注。着重介绍了其酶学特性、基因表达和调控、生物学作用及目前主要在植物抗逆基因工程中的应用研究进展,以期为日后植物ROS和抗逆性研究提供有用信息和思路。