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1.
细胞分裂素合成基因ipt研究进展(综述)   总被引:1,自引:0,他引:1  
异戊烯基转移酶是细胞分裂素生物合成第一步的催化酶,也是限速酶。其编码基因ipt已被克隆,运用生物信息学方法,在拟南芥中鉴定出与微生物同源的编码异戊烯基转移酶的基因家族,推测这些基因可能存在特殊时空表达来调控细胞分裂素的合成途径。本文着重介绍ipt在细胞分裂素合成中的作用和研究进展。  相似文献   

2.
就叶片衰老研究在生理、生化及分子水平上的最新进展,以及有希望应用于农业的、操纵叶片衰老的转基因手段作一简要综述。  相似文献   

3.
植物衰老的分子基础与调控   总被引:8,自引:1,他引:8       下载免费PDF全文
综述了植物衰老过程中的基因表达的上调和下调两种趋势,以及目前延缓植物衰老的调控手段。  相似文献   

4.
就叶片衰老研究在生理,生化及分子水平上的最新进展,以及有希望应用于农业,操纵叶片衰老的转基因手段作一简要综述。  相似文献   

5.
植物叶片衰老过程中的基因表达与调控   总被引:2,自引:0,他引:2  
姚真  高燕萍  杨金水 《遗传》1999,21(4):63-65
衰老是一种器官或组织逐步走向功能衰退和死亡的变化过程〔1〕。它除了代表器官或组织生命周期的终结之外,在发育生物学上也有着重要的意义。叶片的衰老是植物的一个重要发育阶段。在这段时期内,植物在成熟叶片内积累的物质,包括大量的氮、碳有机化合物和矿物质,将被分解并运送至植物其它生长旺盛的部分,其中大部分被转移到种子内,为下一代的生长做好准备〔11〕。对于产生种子的作物,包括绝大多数农作物,这种转移使营养重新分配,对植株保持正常的生长发育与繁殖是十分必要的〔3〕。衰老过程中,叶片细胞在组成成分上有很大的变…  相似文献   

6.
植物叶片衰老过程中基因的表达与调控   总被引:6,自引:0,他引:6  
从衰老相关基因的分离、克隆、表达、调控及叶片衰老延缓几个方面,介绍叶片衰老过程中基因表达调控的研究进展。  相似文献   

7.
转P_(rd29A)-ipt基因对烟草根及侧芽生长的影响   总被引:1,自引:0,他引:1  
利用异戊烯基转移酶(isopentenyl-transferases,ipt)基因转化植物,可明显提高抗逆性和抗病性,延缓叶片衰老。逆境胁迫常会对植物造成很大的伤害,拟南芥的Prd29A启动子受干旱、盐及冷胁迫诱导。构建了Prd29A-ipt植物表达载体,通过农杆菌介导转化普通烟草,获得了能够正常生长的转基因植株。通过表型观察发现,转Prd29A-ipt烟草具有一定的组成型表达,降低了烟草的顶端优势,促进了烟草侧芽的生长,同时,对根的伸长有一定的抑制作用。  相似文献   

8.
植物叶片衰老及其延缓的分子途径   总被引:8,自引:0,他引:8  
综述了植物叶片衰老过程中基因表达的上调和下调两种趋势,以及与转ipt基因研究有关的问题:(1)CTK/IAA平衡;(2)形态发育;(3)抗衰老作用;(4)启动子选择等。  相似文献   

9.
陈烨  刘平丽 《西北植物学报》2023,43(6):1068-1080
植物叶片衰老是一个非常重要的发育过程,涉及大分子的有序分解从而将营养物质从叶片转移到其他器官,对植物的生存和适应至关重要。叶片衰老主要受植物的发育调控,但同时也受内部和外部环境因素的影响,涉及高度复杂的基因调控网络和多层级的调控。近年来的研究表明表观遗传是调控植物叶片衰老的一种重要调控方式。该研究综述了植物叶片衰老过程中的表观遗传调控机制,包括组蛋白修饰、DNA甲基化、ATP依赖的染色质重塑和非编码RNA介导的调控,并对该领域今后的发展方向进行了展望。  相似文献   

10.
植物衰老是植物细胞生长发育的最后一个阶段,其启动的早晚对植物生物量和品质的形成有很大影响。叶片衰老是植物衰老的主要形式,受到内外环境因素的诱导,并被多种转录因子介导的信号传导途径所调控。对叶片衰老调控机制的研究一直是植物衰老研究中的重点。Whirly蛋白作为一类广泛存于植物中的特异转录因子小家族,能与单链DNA分子结合,双定位于细胞器(线粒体或叶绿体)与细胞核中,在植物细胞核和细胞器中发挥多种功能,参与对植物叶片衰老的调控。本文概述了植物Whirly蛋白的结构和定位,重点阐述了Whirly蛋白的功能与细胞衰老关系及其对叶片衰老调节机理的研究进展等,并对未来的研究方向进行了展望。  相似文献   

11.
12.
细胞分裂素在植物抗逆和延衰中的作用   总被引:44,自引:0,他引:44  
王三根 《植物学通报》2000,17(2):121-126
本文综述了细胞分裂素类物质的种类、分布和在植物抗水分胁迫、低温冷害、病虫害等方面的作用以及在延缓果实、叶片、切花等衰老中的效果,讨论了其生理机制、细胞分裂素与其它植物激素的相互关系,并提出了有关细胞分裂素类物质作用机理中值得深入研究的若干问题,如嘌呤型与苯基脲型细胞分裂素的作用特点,细胞分裂素与生长素、脱落酸的协调作用和拮抗作用细胞分裂素的从头合成途径和tRNA途径等。  相似文献   

13.
钙离子对细胞分裂素延缓水稻叶片衰老的抑制作用   总被引:1,自引:0,他引:1  
单独使用细胞分裂素 (BA和 Zeatin,1 0 -9~ 1 0 -5 mol/ L和 Ca2 (1 0 -3 mol/ L)处理水稻离体叶片时 ,二者均对叶片衰老有延缓作用。但当用 Ca2 和细胞分裂素同时处理叶片时 ,细胞分裂素延缓衰老的作用受到 Ca2 的明显抑制。进一步研究表明 ,细胞分裂素和 Ca2 并未协同刺激水稻离体叶片的乙烯生成 ,这样排除了通过乙烯促进叶片衰老的可能性。用可提高细胞质 Ca2 浓度的钙通道载体 A2 31 87处理叶片时 ,可延缓叶片衰老 ;而用可降低胞质 Ca2 浓度的试剂 ,如 EGTA、La Cl3 、Verapamil、氯丙嗪等(1 0 -3 mol/ L)处理叶片时 ,可促进叶片衰老 ,进而排除了细胞分裂素促进 Ca2 的吸收而加快衰老的可能性。  相似文献   

14.
    
Cytokinins and Ca2+ singly retarded senescence of detached rice leaves. When Ca2+ was applied together with cytokinins, the effectiveness of cytokinins was significantly reduced. Ca2+ and cytokinins did not stimulate ethylene production synergistically, ruling out the possibility that ethylene was involved in the inhibition of cytokinin-induced senescence- retarding effect by Ca2+. The experiment with specific compounds known to increase (Ca ionophore A23187), or decrease (EGTA, LaCl3, Verapamil, chlorpromazine) cytosolic Ca2+ level indicated that the elevated cytosolic Ca2+ retards senescence.  相似文献   

15.
The sequence of events and the signals that regulate the remobilization of nitrogen (N) reserves during senescence induced by N starvation were studied in leaf 3, the last fully expanded leaf, in 17-day-old wheat (Triticum aestivum L.) plants. The first event observed was a rapid decrease in the isopentenyl adenosine (iPA) concentration during the first 24 h of N starvation. No differences in t-zeatin riboside and dihydrozeatin riboside concentrations were observed until the end of the assay. During the following 6 days, a decrease in soluble amino acids, chlorophyll, and protein, as well as an increase in soluble sugar concentration and endoproteolytic activity, could be observed. At day 3 of the experiment, the abscisic acid (ABA) concentration in the leaves of N-deprived plants started to increase. After 6 days of N deprivation there was a rise in oxidative stress, as indicated by the increase in malondialdehyde concentration, as well as a decrease in the activities of antioxidant enzymes catalase and ascorbate peroxidase. To analyze interactions with leaf development, the first, second, third, and fourth leaves were studied. iPA concentration decreased in all the leaf stages, including leaf 4, which was not fully expanded. A linear correlation between iPA and protein concentration was determined. These results suggest that the sharp fall in iPA could be the earliest event that induces protein degradation during the development of senescence induced by N deficiency, and that only later is ABA accumulated and oxidative stress developed.  相似文献   

16.
Recent progress in the study of cytokinin metabolism in plants indicates that quantitative analysis of cytokinin nucleotides is essential for elucidation of early steps of the biosynthetic pathway. However, traditional procedures for purification and quantification of cytokinin cannot discriminate the various nucleotides. We describe here a method for separation and determination of cytokinin nucleotides through a series of anion-exchange column chromatography steps followed by liquid chromatography-mass spectrometry. This method enabled us to analyze the amount of each species of cytokinin nucleotide in plant tissues.  相似文献   

17.
多胺与激动素对稀脉浮萍离体叶状体衰老的影响   总被引:12,自引:0,他引:12  
多胺与KT 都可抑制暗诱导衰老的稀脉浮萍(Lem na aequinoctialis)离体叶状体的叶绿素损失,且多胺的作用大于KT。KT 还显著抑制蛋白质的损失与蛋白酶活性的上升,而多胺对此却无大的影响。0.05 m m ol/L的甲基乙二醛二脒基-腙(MGBG)轻微促进叶绿素和蛋白质的损失。0.05 m m ol/L的KT 可抑制衰老过程中腐胺(Put)的上升和亚精胺(Spd)的下降,而对精胺(Spm )无明显影响。在稀脉浮萍中,精氨酸脱羧酶(ADC)活性占优势。KT 可轻微促进ADC 活性,而对鸟氨酸脱羧酶(ODC)和S-腺苷甲硫氨酸脱羧酶(SAMDC)活性无显著影响。讨论了多胺与细胞分裂素在抑制植物叶片衰老过程中作用途径的可能关系  相似文献   

18.
Cytokinin oxidase/dehydrogenase (EC 1.5.99.12) specific activity was determined in leaves and roots of two P. sativum cultivars (cv. Scinado and cv. Manuela) during vegetative development and the effect of UV-B irradiation or elevated temperature was assessed. The measurement of CKX activity during development showed localisation of this enzyme to roots. The reduction in CKX activity in leaves after UV-B irradiation and the increased levels of the enzyme in high temperature-treated plants suggests that the enzymes from the CKX gene family have a different expression during stress responses provoked by different factors and probably are tissue specific. Differences regarding cytokinin oxidase/dehydrogenase activity stress response were observed between the two pea cultivars.  相似文献   

19.
    
Both polyamines and kinetin could retard the loss of chlorophyll during dark-induced senescence in excised frond of Lernna aequinoctialis 6746. The effect of polyamines on retarding the chlorophyll loss was stronger than that of kinetin. Kinetin remarkably inhibited the loss of soluble proteins and the increase of protease activity, while no similar effects were observed from polyamines. An inhibitor of polyamine biosynthesis, methylglyoxal bis- (guanyl- hydrazone) (MGBG), slightly increased the loss of chlorophyll and soluble proteins. During senescience, both the increase of putrescine (Put) content and the decrease of spermidine (Spd) content were inhibited by kinetin at the concentration of 0.05 mmol/L, but the spermine (Spm) level was not affected by kinetin. The arginine decarboxylase (ADC) activity was dominant in frond of Lemna aequinoctialis 6746. Kinetin slightly increased ADC activity, while it had no marked effect on ornithine decarboxylase (ODC) and s-adenosylmethionine decarboxylase (SAMDC). The possible relationship between polyamines and cytokinins in retarding senescence was also discussed.  相似文献   

20.
Summary Tzs and ipt are two Ti plasmid genes coding for proteins with isopentenyltransferase (IPT) activity in vitro. We cloned both genes for protein expression in Escherichia coli and in Agrobacterium tumefaciens, and we investigated differences between the two genes by analysing the properties of the proteins in vitro and in vivo. In vitro, extracts with tzs or ipt-coded proteins had high IPT activity, and the enzymes were identical in most properties. The most important difference was detected in vivo: the tzs-encoded protein was very active in cytokinin production, while the ipt protein required overexpression in order to obtain measurable activity in bacteria. In both cases, rans-zeatin was the major product of the gene activity. Formation of this cytokinin requires a hydroxylase function in addition to the IPT reaction. No such activity could be ascribed to tzs or ipt-encoded proteins in vitro or in vivo, but cytokinin hydroxylase activity was detected in cells and extracts of E. coli, regardless of the presence or absence of the cytokinin genes. Based on these results it is proposed that both genes code for a single enzyme activity (isopentenyltransferase), that the genes and proteins are adapted for function either in bacteria (tzs) or in transformed plant cells (ipt), and that in both prokaryotic and eukaryotic cells hydroxylation to trans-zeatin is a function contributed by host enzymes.Abbreviations DMAPP dimethylallylpyrophosphate - iP isopentenyladenine - iPA isopentenyladenosine - iPMP isopentenyladenosine 5-monophosphate - IPT isopentenyltransferase - trans-Z trans-zeatin  相似文献   

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