Paraquat Resistance in Leaf Discs of PAAG12-IPTModified Gerbera Is Related to the Activities of Superoxide Dismutase, Catalase, and Dehydroascorbate Reductase

In this paper, using in vitro leaf disc culture system, the changes of contents of chlorophylls, carotenoids, soluble protein, thiobarbituric acid reactive substance （TBARS）, and activities of antioxidant enzymes were investigated during the incubation of leaf discs of PSAG12-IPT modified gerbera in 0, 25, 50 μmol L^-1 paraquat （PQ） under continuous light intensity of 130 0tool m-2 s-1, compared with the control plant （wild type）. The results showed that PQ treatment significantly decreased the contents of chlorophylls, carotenoids, and soluble protein, therefore, promoted leaf senescence. However, the decreases in the leaf discs of modified gerbera were considerably smaller. The activities of superoxide dismutase （SOD）, catalase （CAT）, and dehydroascorbate reductase （DHAR） were significantly increased by PQ treatment and with the increasing of PQ concentration, particularly in the modified plants. The activities of ascorbate peroxidase （APX） and guaiacol peroxidase （GPX） could not be detected in the leaf discs of PQ treatments, which suggested that they were labile to the oxidative stress induced by PQ. As a product of lipid peroxidation, TBARS significantly increased in content with the increase of PQ concentration, while its concentration in the modified plants was significantly lower than that of control plants. Therefore, it could be concluded that the chimeric gene PSAG12-IPTtransfonnexi gerbera leaves had higher antioxidative potential, thus causing the delay of senescence under oxidative stress induced by PQ.     

干旱胁迫对番茄活性氧代谢的影响

干旱胁迫导致番茄叶片ＲＷＣ、Ｃｈｌ和可溶性蛋白质含量下降，质膜透性和ＡＴＰａｓｅ活性提高．短期干旱胁迫可提高叶片ＳＯＤ和ＣＡＴ活性．４ｄ以内的干旱胁迫后复水，ＲＷＣ、Ｃｈｌ和可溶性蛋白质含量升高，清除活性氧保护酶ＳＯＤ、ＰＯＤ和ＣＡＴ的活性显著提高，抗氧化物质ＡｓＡ和ＧＳＨ的水平得到恢复，ＭＤＡ得到清除，自动氧化速率降低，重新建立了活性氧产生与清除的平衡系统，ＡＴＰａｓｅ活性降低，膜系统的损伤得到修复，透性降低，恢复了原有正常的生理代谢机能．长期干旱胁迫导致叶片清除活性氧的平衡体系受到破坏，ＳＯＤ、ＰＯＤ和ＣＡＴ活性以及ＡｓＡ和ＧＳＨ的含量下降，膜脂过氧化加剧，自动氧化速率提高，ＭＤＡ积累，影响番茄正常代谢，从而加速衰老进程     

水稻氮素供需差与不同叶位叶片氮转运和衰老的关系

 采用去穗和疏花方法调节稻穗氮需求量 ,研究了水稻氮素供需差 (NSDB)对不同叶位叶片氮转运和衰老的影响。结果表明 ,在NSDB <0的条件下 (对照 ) ,植株上部 4张叶输出氮素 ,叶片正常衰老 ;随NSDB提高 ,顶部叶片尤其是顶 4叶的氮素输出显著减少 ,叶片MDA含量下降 ,SOD和CAT酶活力提高 ,上位叶与下位叶之间的叶色差缩小 ;当NSDB >0以后 (去穗 ) ,上部 4叶的氮积累量不仅未减少 ,相反还有显著的增加 ,叶片的衰老进程被延缓。研究证实顶 4叶叶色受氮素供需差的影响最大 ,当土壤供氮不能满足库需氮时 ,顶 4叶叶色浅于顶 3叶     

新疆甜瓜高效再生体系的建立及NPR1/HRP双价抗病基因转化

以厚皮甜瓜5d龄无菌苗子叶为外植体,MS和1/2MS为基本培养基,研究了添加6-BA、IAA和卡那霉素不同浓度,进行甜瓜再生体系与根癌农杆菌介导的转化体系的建立。结果表明:甜瓜子叶最适宜的不定芽分化培养基为MS+6-BA 1.0mg/L+IAA 0.3mg/L,芽伸长培养基为MS+6-BA 0.75mg/L+IAA 0.3mg/L,生根培养基为1/2MS+IAA 0.3mg/L,适宜的转化条件为外植体预培养48h,农杆菌菌液浓度为OD₆₀₀=0.3～0.4,侵染时间为15min,22℃暗培养48～55h。经75mg/L的卡那霉素筛选,共获得再生甜瓜幼苗21株,其中8棵经PCR鉴定证明NPR1/HRP双价抗病基因已经整合到甜瓜基因组中,即转化率为38%。     

干旱胁迫对银杏衰老期叶片生理生化特性的影响

以银杏5 a生盆栽实生苗为材料,通过自然干旱处理,研究干旱对银杏衰老期叶片部分生理指标的影响。结果表明:与对照相比,处理组叶绿素含量下降;电导率和MDA含量上升;SOD和CAT的活力先上升后下降;脯氨酸逐渐积累,可溶性蛋白含量呈现先上升后下降的趋势。说明随着干旱胁迫的加剧,引起了膜脂氧化加剧,加快了银杏叶片的衰老。     

控释氮肥对杂交水稻生育后期根系形态生理特征和衰老的影响

采用微区和小区试验的方法,研究了控释氮肥对杂交水稻生育后期根系形态生理特征及对根系衰老过程中膜脂过氧化产物和活性氧清除酶活性的影响。研究表明,施用控释氮肥,明显地增加杂交水稻生育后期的根干重、根长和根长密度,而根半径减小;提高根系活力和吸收面积,使杂交水稻生育后期根系中MDA含量降低和SOD、POD和CAT的活性提高。控释氮肥中,氮的逐渐释放,可减少具有强烈伤害的活性氧产物速率及其累积数量,提高活性氧清除酶的活性,在很大程度上延缓了杂交水稻生育后期根系的衰老和吸氮能力的衰退。     

氮素对菠菜衰老生理指标的影响

田间小区试验研究了氮素与菠菜衰老的关系。结果表明,菠菜生长前期,植株根系活力增强,叶片叶绿素含量、光合速率及SOD、POD、CAT等保护酶活性升高,但生长后期均持续降低;而叶片电解质渗漏及丙二醛(MDA)含量在全生育期内则持续增加。在施氮量低于600.kg/hm2条件下,增施氮素可显著降低菠菜叶片的电解质渗透率及MDA含量,增强SOD、POD和CAT等保护酶活性及根系活力,提高叶绿素含量及光合速率,延缓菠菜衰老,进而提高菠菜产量。菠菜收获时,氮素用量600.kg/hm2处理的叶片电解质渗透率和MDA含量分别比对照(不施氮)降低50.9%、67.2%,SOD、POD和CAT活性及根系活力分别高59.2%、478.4%、290.9%和131.3%;叶绿素含量及光合速率分别高59.6%、131.3%,增产率达88.0%。施氮量达900.kg/hm2时则发生负效应,虽然产量比对照增产75.3%,但比600.kg/hm2施氮量减产6.7%。     

Growth responses and foliar sensitivities of native herbaceous species to ozone exposures

This paper reports on open-top chamber studies investigating the effects of different O₃ exposures on native herbaceous plant species. Plants were grown up from seeds, potted into natural soils and exposed to near-ambient O₃ levels during one growing season. A wide range of visible symptoms was apparent during the exposures. Species such as Rumex obtusifolius, Senecio vulgaris or Sonchus asper showed leaf colorations (e.g. reddish pigmentation) that probably indicate a non-specific stress response. In other species especially of the genera Malva and Cirsium the symptoms produced by O₃ appeared to be similar to those characteristic for O₃-specific foliar injury (stippling, flecking). In almost all species tested, O₃ caused premature leaf senescence, which was sometimes associated with premature leaf abscission. However, earlier senescence did not necessarily result in changes in plant growth. Of all species tested, Malva sylvestris was found to be the most sensitive in terms of growth reduction and lower seed production.