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。     

小麦叶片衰老过程中CAT和APX活力及其同工酶谱的变化

小麦叶片在连体自然衰老和离体诱导衰老过程中，过氧化氢酶（ＣＡＴ）活力比抗坏血酸过氧化物酶（ＡＰＸ）活力下降得早。当ＣＡＴ活力处于较低水平时，ＡＰＸ仍然维持较较活力，且ＡＰＸ活力与Ｈ２Ｏ２含量呈显著负相关，经同工酶电泳分析，离体叶片暗诱导衰老过程中，ＣＡＴ同工酶带无增减，只是活性免疫，而ＡＰＸ同工酶带则有增加，ＡＰＸ在小麦叶片衰老的中后期可能起着比ＣＡＴ更重要的清除Ｈ２Ｏ２的作用。     

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.     

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.     

龙眼胚性培养物APX同工酶的分析方法建立及其在龙眼体胚发生过程中的变化

以龙眼胚性培养物为材料,进行抗坏血酸过氧化物酶(APX)同工酶的聚丙烯酰胺凝胶电泳分析方法研究,建立一套适合分离龙眼胚性培养物中不同类型APX同工酶的垂直板聚丙烯酰胺凝胶电泳方法;进一步研究了APX同工酶在龙眼体胚发生过程中的变化,发现在胚性愈伤组织、球形胚、子叶形胚3个阶段APX同工酶存在差异.     

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。     

对猪血品质影响的研究

通过近年多次试验，对猪血短期贮存的护色效果进行了研究．结果表明，在猪血中加入抗氧化剂──抗坏血酸钠2g／L和发色助剂──烟酰胺0．5g／L，在0—5℃环境中贮存2～4d效果最佳．并研究证实亚硝酸钠不能作为猪血发色剂使用．     

Phytotoxicity of Roundup Ultra 360 SL in aquatic ecosystems: Biochemical evaluation with duckweed (Lemna minor L.) as a model plant

Glyphosate-based herbicides (e.g. Roundup Ultra 360 SL) are extensively used in aquatic environment. Although glyphosate is more environmental favorable than many other herbicides, it may be exceptionally dangerous for aquatic ecosystems through high water solubility. Thus, the aim of the work was quantification of influence of Roundup Ultra 360 SL (containing isopropylamine salt of glyphosate as an active ingredient) on biomass and chlorophyll content within duckweed (Lemna minor L.). Moreover, changes in polyamine content and activity of such antioxidative enzymes as catalase (CAT) and ascorbate peroxidase (APX) were assayed in order to determine the biochemical mechanisms of L. minor response to the herbicide treatment. Obtained results showed that phytotoxicity of the herbicide was connected with decrease in chlorophyll-a, b and a+b content, and reduction of biomass growth. Roundup, similarly to some abiotic and biotic stressors, caused over-accumulation of putrescine, spermidine and total polyamines (PAs) within duckweed tissues. In addition an increase in CAT and APX activities suggested that stress generated by the herbicide treatment was at least partially connected with oxidative burst. Intensity of the duckweed responses to the herbicide was dependent on the applied herbicide level and/or duration of treatment.     

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.     

Differential expression of the ascorbate oxidase multigene family of Camellia sinensis in response to stress

Apoplastic ascorbate oxidase (AO) plays a major role in cell growth. Although AO genes have been studied in depth, some articles have mistakenly identified AO homologues as AO genes. Overall, the divergence between AO genes and AO homologues has not been explored. Meanwhile, there is little information concerning AO and the AO homologue with respect to Camellia sinensis. In the present study, one CsAO homologue and three CsAOs were confirmed by RT-PCR amplification, cloning and sequencing. Multicopper oxidase type 1 (PF00394), type 2 (PF07731) or type 3 (PF07732) domains and one transmembrane helix were the key domains for each member of the cupredoxin family. The CsAOs with their counterparts from seven dicotyledonous plants and three monocotyledonous plants were used to build phylogenetic tree and compare the deduced polypeptides. CsAO may be strongly expressed in the stretch expanded tissues, including bud and root. The abiotic stress-induced expression pattern of the CsAO homologue (CsAO2) is similar to those of CsAO1, CsAO3 and CsAO4. A new and very large group of AO homologues, which may function as AO genes, was present in both dicotyledonous and monocotyledonous plants. Our study may help in identifying stress-responsive AO genes of plants.