植物抗逆性与光呼吸作用之间的关系

用Na_2SO_3溶液浸泡,可以影响菠菜叶片中超氧物歧化酶的活性。较低浓度(0.1、1、10ppm)的该溶液使酶活性增加,而100ppm的该溶液则降低此酶的活性。同时发现叶片中光呼吸关键酶,即乙醇酸氧化酶活性也随着发生正相关的变化。讨论植物受SO_3~(2-)胁迫后,乙醇酸氧化酶的活性变化与植物抗逆性的产生可能存在密切的关系。     

植物中草酸积累与光呼吸乙醇酸代谢的关系

对几种C3 和C4 植物中草酸含量及相应的乙醇酸氧化酶活性测定结果表明 :叶片光呼吸强度及其关键酶活性大小与草酸积累量没有相关性 ;植物根中均能积累草酸 ,但未测出乙醇酸氧化酶活性。烟草根、叶中的草酸含量在不同生长时期差异明显 ,且二者呈极显著正相关 (y =2 .5 6 5lnx 2 .137,r =0 .749,P <0 .0 0 1) ,说明根中草酸可能来自叶片。氧化乙醇酸的酶的活性与氧化乙醛酸的酶的活性呈极显著线性正相关 (y =0 .2 41x 0 .0 0 6 ,r=0 .96 7,P <0 .0 0 0 1) ,进一步证实是乙醇酸氧化酶催化了两种底物的反应。烟草在不同生长期叶片中草酸总含量变化与相应的乙醇酸氧化酶活性变化亦没有相关性 ;低磷胁迫可显著诱导烟草根叶中的草酸形成和分泌 ,但并未影响乙醇酸氧化酶活性 ,进一步证明草酸积累与该酶活性大小无关     

两种红树叶的几种酶的生理特性与海滩盐度的相关性初探

本文是福建九龙江口红树林研究的一部分,主要讨论两种红树植物(秋茄,桐花树)叶片中的几种酶对海滩盐度(3—12‰范围内)变化的反应,测定结果如下：1,桐花树叶片过氧化物酶同工酶和细胞色素氧化酶同工酶的含量对土壤盐度变化的反应表明：土壤盐度(3—12‰)提高,过氧化物酶和细胞色素氧化酶同工酶的谱带加深、加宽,而且谱带中出现新酶带。 2．当海滩盐度提高时,桐花树叶片的过氧化物酶的活性提高,秋茄叶片的乙醇酸氧化酶的活性减弱。 3．两种红树植物叶绿素含量与土壤盐度相关性显示出：当土壤盐度在3—8‰范围时,叶绿素含量变化不大;8—10‰时有一个高峰,大于10‰时又下降。可能红树植物对海滩盐度适应有一个临界值。     

植物中草酸积累与光呼吸惭醇酸代谢的关系

对几种Ｃ３和Ｃ４植物中草酸含量及相应的乙醇酸氧化酶活性测定结果表明,叶片光呼吸强度及其着急酶活性大小与草酸积累量没有相关性;植物根中均能积累草酸,但未测出乙醇酸氧化酶活性。烟草根、叶中的草酸含量在不同生长时期差异明显,且二者呈显著正相关（ｙ＝２．５６５ｌｎｘ＋２．１３７,ｒ＝０．７４９,Ｐ〈０．００１）,说明振中到可能来自叶片。氧化乙醇酸的瓣活性与氧化乙醛酸的酶的活性呈极显著线性正相关（ｙ＝０．２     

荞麦与大豆叶片中草酸含量差异及其可能的原因

用1/5浓度Hoagland营养液培养荞麦和大豆幼苗l0 d后,荞麦叶片、根及其分泌物中的草酸含量均明显高于大豆,说明荞麦叶片的草酸形成能力强.荞麦叶片中存在少量的草酸氧化酶活性,而大豆中未检测到该酶活性,表明荞麦具有一定的降解草酸的能力.乙醇酸氧化酶(GO)催化乙醇酸氧化的活性两种植物之间虽差异不明显,但该酶催化乙醛酸氧化的活性荞麦显著高于大豆.荞麦GO对乙醛酸的Km值明显低于大豆GO,同时其乙醛酸含量也较高,因此其叶片中由乙醛酸形成草酸的速率应高于大豆.由此认为,由乙醛酸氧化生成草酸可能是植物草酸合成限速步骤之一,其反应速率高低可能导致不同种类植物叶片中草酸含量的差异.     

水稻叶片中的草酸积累及其与抗白叶枯病的关系（简报）

测定不同生长时期及感染白叶枯病菌前后,水稻叶片中的草酸含量、乙醇酸氧化酶活性变化的结果,进一步证实乙醇酸氧化酶同时具有氧化乙本钱酸的活性,但叶片另的内源草酸含量变化与乙醇酸氧化酶活性变化无关,高感品种玉梅１５３和高抗品种中二占在染病前后内源草酸含量变化之间并无显著差异。     

植物的乙醇酸氧化酶

乙醇酸氧化酶存在于植物细胞过氧物酶体中,是一种黄素蛋白,以FMN为辅基,含8个亚基。催化乙醇酸氧化为乙醛酸和乙醛酸氧化为草酸。受光活化。硫化钠和氰化物促进其活性:巯基抑制剂、α-羟基磺酸类、α-羟基丁炔酸抑制其活性。多种代谢物对其活性有调节作用。为光呼吸的关键酶之一,其活性随植物发育、矿质营养及感病而发生变化。     

水稻叶片中的草酸积累及其与抗白叶枯病的关系(简报)1

测定不同生长时期及感染白叶枯病菌前后,水稻叶片中的草酸含量、乙醇酸氧化酶活性变化的结果,进一步证实乙醇酸氧化酶同时具有氧化乙醛酸的活性,但叶片中的内源草酸含量变化与乙醇酸氧化酶活性变化无关。高感品种玉梅153和高抗品种中二占在染病前后内源草酸含量变化之间并无显著差异。     

腐殖酸钠对植物生长的刺激作用

应用溶液培养方法研究了腐殖酸钠对植物生长的刺激作用。小麦、蕃茄、棉花等植物的苗期生长,特别是根的生长受到腐植酸钠的显著促进。刺激生长的腐殖酸钠浓度因来源而异,且刺激作用有一定的作用时间。曾观察到腐殖酸钠处理提高了植物幼苗对低温、干旱、缺磷的抗逆作用。为了将腐殖酸钠的刺激作用与已知植物激素的作用相比较,用生物试法测试了富里酸的细胞分裂素活性及生长素活性。发现巩县富里酸从50 ppm到3000 ppm都有激动素活性,但随着贮存时间的延长而改变,活性范围不稳定。也观察到250 ppm富里酸有生长素活性。此外还初步证实富里酸能抑制根中吲哚乙酸氧化酶在体外的活性。     

茉莉酸甲酯对水稻幼苗光呼吸代谢的影响

经2．5×10-4mol／L茉莉酸甲酯（MJ）处理后的水稻幼苗,在处理后第2天即表现出RuBP加氧酶活性的明显升高,至处理后第4天,叶片中乙醇酸氧化酶的活性也升高,同时叶片中的乙醇酸累积量也明显高于对照。经α-HPMS预处理后的幼苗叶片材料中,这种乙醇酸累积量升高的程度更大,表明2．5×10-4mol／LMJ处理能促进水稻幼苗光呼吸的增强,但2．5×10-7mol／LMJ处理对叶片中乙醇酸的累积和光呼吸过程中的有关酶系没有影响。     

植物乙醇酸氧化酶分离纯化方法的改进

通过缩短DEAE-Cellulose柱长度,加快流速并采用pH8.8的80mmol.L-1Tris-HCl为洗脱液,可在9小时内快速地从菠菜、菜心和豆角绿叶中纯化得到乙醇酸氧化酶。该酶具高活性(54.6～197.0U.mg-1)及高等电点(pI>10.0)。产率为4.1%～71.5%,纯化倍数为21.6～122.68。经SDS-PAGE检测均有40kD带,表明3种植物乙醇酸氧化酶的亚基大小无区别。     

植物乙醇酸氧化酶分离纯化方法的改进

通过缩短DEAE-Cellulose柱长度, 加快流速并采用pH8.8的80 mmol.L-1 Tris-HCl为洗脱液, 可在9小时内快速地从菠菜、菜心和豆角绿叶中纯化得到乙醇酸氧化酶。该酶具高活性(54.6～197.0 U.mg-1)及高等电点(pI >10.0)。产率为4.1%～71.5%, 纯化倍数为21.6～122.68。经SDS-PAGE检测均有40 kD带,表明3种植物乙醇酸氧化酶的亚基大小无区别。     

Glycolate oxidase isoforms are distributed between the bundle sheath and mesophyll tissues of maize leaves

Glycolate oxidase (EC 1.1.3.15) activity was detected both in the bundle sheath (79%) and mesophyll (21%) tissues of maize leaves. Three peaks of glycolate oxidase activity were separated from maize leaves by the linear KCl gradient elution from the DEAE-Toyopearl column. The first peak corresponded to the glycolate oxidase isoenzyme located in the bundle sheath cells, the second peak had a dual location and the third peak was related to the mesophyll fraction. The mesophyll isoenzyme showed higher affinity for glycolate (Km 23 micromol x L(-1)) and a higher pH optimum (7.5-7.6) as compared to the bundle sheath isoenzyme (Km 65 micromol x L(-1), pH optimum 7.3). The bundle sheath isoenzyme was strongly activated by isocitrate and by succinate while the mesophyll isoenzyme was activated by isocitrate only slightly and was inhibited by succinate. It is concluded that although the glycolate oxidase activity is mainly attributed to the bundle sheath, conversion of glycolate to glyoxylate occurs also in the mesophyll tissue of C4 plant leaves.     

Photoinactivation and protection of glycolate oxidase in vitro and in leaves

Glycolate oxidase that was partially purified from pea leaves was inactivated in vitro by blue light in the presence of FMN. Inactivation was greatly retarded in the absence of O2. Under aerobic conditions H2O2 was formed. The presence of catalase, GSH or dithiothreitol protected glycolate oxidase against photoinactivation. Less efficient protection was provided by ascorbate, histidine, tryptophan or EDTA. The presence of superoxide dismutase or of hydroxyl radical scavengers had no, or only minor, effects. Glutathione suppressed H2O2 accumulation and was oxidized in the presence of glycolate oxidase in blue light. Glycolate oxidase was also inactivated in the presence of a superoxide-generating system or by H2O2 in darkness. In intact leaves photoinactivation of glycolate oxidase was not observed. However, when catalase was inactivated by the application of 3-amino-1,2,4-triazole or depleted by prolonged exposure to cycloheximide a strong photoinactivation of glycolate oxidase was also seen in leaves. In vivo blue and red light were similarly effective. Furthermore, glycolate oxidase was photoinactivated in leaves when the endogenous GSH was depleted by the application of buthionine sulfoximine. Both catalase and antioxidants, in particular GSH, appear to be essential for the protection of glycolate oxidase in the peroxisomes in vivo.     

Induction of glycolate oxidase by SO2 in Nicotiana tabacum

In contrast to the inhibitory action of sulfite on glycolate oxidase, the specific activity of the enzyme in tobacco leaves exposed to SO₂ for 18 hr increases in proportion to the SO₂ concentration. This increase is strongly reduced by pretreatment with cycloheximide. As a consequence of induced de novo synthesis of glycolate oxidase the glycolate content of the leaves is markedly reduced after 18 hr exposure to SO₂.     

光和底物对乙醇酸氧化酶的基因表达的诱导

从菠菜中提纯了乙醇酸氧化酶并制备其抗体,经免疫双扩散、Ｗｅｓｔｅｒｎｂｌｏｔ和Ｎｏｒｔｈｅｒｎｂｌｏｔ证实水稻和豌豆黄化苗中不存在乙醇酸氧化酶。在黑暗中,底物可促进该酶基因的表达,而在黄化苗光照初期,推测光可能是不经过底物促进该酶基因的表达。     

Effect of butyl 2-hydroxy-3-butynoate on sunflower leaf photosynthesis and photorespiration

Detached leaves and whole plants of sunflower were supplied with butyl 2-hydroxy-3-butynoate (BHB), a competitive inactivator of glycolate oxidase, to evaluate the possibility of inhibiting photorespiration and increasing photosynthetic efficiency. In all treatments in vivo and in vitro, BHB inhibited glycolate oxidase. With partially purified glycolate oxidase from spinach leaves, the apparent K_i for BHB was 13.2 micromolar.     

Non-synchronous increases in activities of peroxisomal enzymes in etiolated mung bean seedling leaves after illumination

When etiolated 4-day-old seedlings of mung bean were illuminated,catalase, glycolate oxidase and hydroxypyruvate reductase activitiesin the primary leaves increased non-synchronously. Under intenselight, glycolate oxidase activity increased while catalase activitydid not. Phytochrome seems to be involved in increases in allthree enzyme activities. (Received August 10, 1977; )