脱落酸（ABA）在蒜苔衰老中的作用

蒜苔在切除珠蒜后可减少贮存中干物质的损失,延缓衰老,在切口处施加外源ABA可加速苔干叶绿素的破坏和组织的老化,气相色谱与色质联用法检测完整蒜苔和无珠蒜蒜苔各部分组织中ABA含量在衰老过程中的变化,发现无珠蒜苔干上,中,下各段ABA含量在衰老进程中是逐步减少的,变化幅度小,而带有珠蒜的苔干各相应段和珠蒜的ABA含量均有一迅速增加而后减少的过程,珠蒜的ABA含量最大,ABA含量高峰出现时间最早,苔干各段ABA含量按上,中,下顺序依次减少,高峰出现的时间也是由上至下依次推迟,没有发现蒜苔在衰老过程中有乙烯放出,外加乙烯对其衰老进程影响不大,本文认为珠蒜是蒜苔衰老的关键部位,能加速苔干衰老的ABA主要是在珠蒜中合成的,并自上向下极性运往苔干组织,进而动员物质的再分配,起着信息传递作用,蒜苔的衰老过程可分为“准备期”和“活跃期”两个阶段。     

分析拟南芥叶片在激素促进的衰老中内源激素变化来解析抑制磷脂酶Dα1延缓激素促进衰老的机制

采后衰老进程在很大程度上受到内源和外源激素的影响。抑制拟南芥中磷脂酶Dα1（phospholipaseDtxl,PLDod）的表达后,使得外源脱落酸（abscisic acid,ABA）和乙烯加速的离体叶片衰老过程在一定程度上得到了缓解。然而,内源激素在这个过程中的作用尚不清楚。本研究对比分析了野生型和PLDα1缺失型两种基因型拟南芥叶片在3种不同人工老化过程中（离体诱导的、外源ABA和乙烯促进的衰老过程）,内源ABA,茉莉酸甲酯（methyl jasmonate,MeJA）、吲哚乙酸（indole-3-acetic acid,IAA）、玉米素核苷（zeatin riboside,ZR）和赤霉素（gibberellic acid,GA,）的含量变化。这5种激素对3种不同衰老处理方式的响应模式表明了人工老化过程存在着两个不同阶段,并且在衰老早期每种激素的变化模式相同。PLDα1功能缺失使得激素加速的衰老过程得以延缓,这与内源ABA、MeJA、ZR和IAA的含量变化有关。而与GA、的含量变化无关。同时,ZR和IAA的变化模式也说明了这两种激素的变化可能是缺失PLDα1延缓激素加速的衰老过程这一事件的原因而非结果。     

6-(艹卡)基腺嘌呤对离体蒜苔中引入~3H-葡萄糖再分配的调节

离体蒜苔在贮放过程中,苔茎中的营养物质能大量、高效地向顶端珠蒜转移。蔡可和娄成后证明激动素处理苔茎基部能显著抑制这一转移过程。本文采用同位素示踪进一步研究了细胞分裂素6-苄基腺嘌呤(BA)对蒜苔营养物质再分配的调节。实验材料分幼嫩蒜苔及衰老蒜苔。幼嫩蒜苔购自市场,衰老蒜苔是前者在25℃下放置10     

分析拟南芥叶片在激素促进的衰老中内源激素变化来解析抑制磷脂酶Dα1延缓激素促进衰老的机制

采后衰老进程在很大程度上受到内源和外源激素的影响。抑制拟南芥中磷脂酶Dα1 (phospholipase Dα1, PLDα1)的表达后,使得外源脱落酸（abscisic acid,ABA）和乙烯加速的离体叶片衰老过程在一定程度上得到了缓解。然而,内源激素在这个过程中的作用尚不清楚。本研究对比分析了野生型和PLDα1缺失型两种基因型拟南芥叶片在3种不同人工老化过程中（离体诱导的、外源ABA和乙烯促进的衰老过程）,内源ABA,茉莉酸甲酯（methyl jasmonate,MeJA）、 吲哚乙酸（indole 3 acetic acid,IAA）、玉米素核苷（zeatin riboside,ZR）和赤霉素（gibberellic acid,GA3）的含量变化。这5种激素对3种不同衰老处理方式的响应模式表明了人工老化过程存在着两个不同阶段,并且在衰老早期每种激素的变化模式相同。PLDα1功能缺失使得激素加速的衰老过程得以延缓,这与内源ABA、MeJA、ZR和IAA的含量变化有关,而与GA3的含量变化无关。同时,ZR和IAA的变化模式也说明了这两种激素的变化可能是缺失PLDα1延缓激素加速的衰老过程这一事件的原因而非结果。     

贮藏过程中蒜苔细胞内含物再分配的激素控制

在10～15℃黑暗条件下,虽无光合作用和矿物质及水分的供应,但经长期贮藏的蒜苔,在顶端可形成与地下鳞茎相似的气生鳞茎(珠蒜),其所需的营养物质,完全是靠衰退蒜苔苔茎细胞内含物的转移和再利用;所形成的珠蒜大小与蒜苔苔茎重量之间呈明显的正相关,苔茎越重最后形成的珠蒜越大。利用GA处理蒜苔不同部位(基部或顶端),可阻止或促进苔茎内含物的再分配。GA处理基部可提高苔茎活力,明显防止苔茎衰老和阳抑细胞内含物向珠蒜转移,起到防衰的作用。KT的效果不如GA明显。     

磷脂酶Dδ对拟南芥叶片衰老过程中内源ROS和激素含量的影响

活性氧（ROS）和植物激素是植物衰老过程中重要的内在或者外在的调控因子。我们发现,相对于离体诱导的衰老过程,在脱落酸（ABA）和乙烯（ethylene）促进的衰老过程中有较多的活性氧积累;在对拟南芥磷脂酶Dδ（PLDδ）缺失型突变体的研究中发现,与野生型相比,突变体在衰老过程中产生较少的活性氧。我们比较了上述两种基因型的离体叶片在离体、ABA和ethylene三种衰老处理下内源的ABA、茉莉酸甲酯（MeJA）、玉米素核苷（Zeatin Riboside, ZR）和吲哚乙酸（IAA）的含量变化,发现每一种激素对上述三种衰老处理的响应模式都很相似。在离体诱导的衰老中,两种基因型拟南芥的内源激素含量没有差异;而在ABA促进的衰老过程中,PLDδ缺失型突变体叶片中的MeJA的含量较低,ZR和IAA含量较高;在乙烯促进的衰老过程中,突变体中的ABA和MeJA的含量较低,ZR和IAA含量较高。上述内源激素的这种变化可能有助于延缓突变体的衰老。     

H_2O_2参与离体蒜苔细胞内含物再分配的调控(英文)

植物生长发育过程中经常发生新老器官更替和细胞内含物的再分配、再利用。Lepold提出新生器官向衰老器官传递某种信息 ,动员后者细胞内含物向前者再分配。但是该信息的化学本质迄今仍不清楚。大蒜 (Alliumsativum)的离体蒜苔是研究细胞内含物再分配的良好材料。细胞内含物大量从苔茎向珠蒜中再分配 ,结果珠蒜显著膨大而苔茎衰老死亡。蔡可等发现赤霉素 (GA3)处理可有效抑制细胞内含物再分配。我们此前的研究发现GA3处理苔茎基部可显著改变珠蒜和苔茎H2 O2 代谢。本研究中我们分别用GA3和 3-氨基 - 1 ,2 ,4-三唑 (AT)H2 O2 清除酶catalase的专一性抑制剂处理珠蒜 ,结果发现GA3和AT均可有效抑制离体蒜苔细胞内含物再分配 (Fig .1 )。根据浓度不同 ,H2 O2 可以诱导细胞产生保护性反应或凋亡。细胞内含物再分配过程中 ,珠蒜H2 O2 浓度显著下降后保持于低水平 ,相反苔茎H2 O2 浓度极显著升高 1 0倍以上 ,而且细胞内含物转移早的苔茎下部H2 O2 峰值出现也早 (Fig .2 )。GA3或AT处理珠蒜 ,珠蒜H2 O2 浓度显著提高而苔茎H2 O2 浓度保持稳定的低水平或峰值显著推迟 (Fig .2 )。可见苔茎高浓度的H2 O2 诱导了苔茎细胞凋亡并把细胞内含物转移给珠蒜。已知约 2 %的呼吸耗氧生成H2 O2 。珠蒜呼吸速率显著高于苔茎 (王     

拟南芥叶片衰老过程中细胞溶血磷脂和膜脂不饱和度的变化

细胞膜的流动性和渗透性的改变是植物衰老过程中一个内在的、具有破坏性的变化。膜脂组成中,溶血磷脂的出现是膜伤害的一个重要标志;膜脂双键数目的变化是影响膜流动性的主要因素。应用脂类组学的方法,检测了拟南芥野生型及其磷脂酶Dδ (PLDδ)缺失型突变体在离体诱导的、脱落酸（abscisic acid, ABA）和乙烯（ethylene）促进的衰老过程中,溶血磷脂（lysophospholipids, lysoPLs）的分子变化,并通过计算膜脂双键指数（double bond index, DBI）表征了膜流动性的变化。结果表明,在离体诱导的衰老过程和乙烯促进的衰老过程中,溶血磷脂的总含量和各溶血磷脂分子的变化不显著,而在ABA促进的衰老过程中溶血磷脂总含量和部分溶血磷脂分子均显著升高;在上述三种衰老处理下,总膜脂的DBI均下降,但是离体诱导和激素促进的的衰老过程中各类膜脂的DBI的变化却不同。同时我们还发现,抑制PLDδ基因表达降低了ABA促进的衰老过程中溶血磷脂的产生、减缓了ABA和乙烯促进的衰老过程中总的膜脂的DBI的降低。     

H2O2参与离体蒜苔细胞内含物再分配的调控

植物生长发育过程中经常发生新老器官更替和细胞内分物的再分配，再利用。Lepold提出新生器官向衰老器官传递某种信息，动员后者细胞内含物向前者再分配。但是该信息的化学本质迄今仍不清楚。大蒜（Allium sativum)的离体蒜苔是研究细胞内分物再分配的良好材料，细胞内含物大量从苔茎向珠蒜中再分配。结果珠蒜显著膨大而苔茎衰老死亡。蔡可等发现赤霉素（GA3）处理可有效抑制细胞内含物再分配。我们此前的研究发现GA3处理苔茎基部可显著改变珠蒜和苔茎H2O2代谢。本研究中我们分别用GA3和3－氨基－1，2，4－三唑（AT）H2O2清除酶catalase的专一性抑制剂处理珠蒜，结果发现GA3和AT均可有效抑制离体蒜苔细胞内含物再分配（Fig.1)。根浓度不同，H2O2可以诱导细胞产生保护性反应或凋亡，细胞内含物再分配过程中珠蒜H2O2浓度显著下降后保持于低水平，相反苔茎H2O2浓度极显著升高10倍以上，而且细胞内含物转移早的苔茎下部H2O2峰值出现也早（Fig.2)。GA3或AT处理珠蒜，珠蒜H2O2浓度显著提高而苔茎H2O2浓度保持稳定的低水平或峰值显著推迟（Fig.2)，可见苔茎高浓度的H2O诱导了苔茎细胞凋亡并把细胞内含物转移给珠蒜。已知经2％的呼吸耗氧生成H2O2。珠蒜呼吸速率显著高于苔茎（王文宏等）表明珠蒜H2O2生成速率大于苔茎。珠蒜H2O2清除酶peroxidase和catalase活性逐步下降，与苔茎相反（Fig3,4)，可见珠蒜H2O2浓度应该显著高于苔茎，但事实上珠蒜H2O2水平显著低于苔茎，已知H2O2具有寿命长，易扩散和运输的特点，可见苔茎中积累的H2O2应该主要来自珠蒜。GA3和AT处理对珠蒜和苔茎中H2O2代谢的作用进一步表明，H2O2可能参与离体蒜苔细胞内含物再分配的调控。     

磷脂酶Dδ对拟南芥叶片衰老过程中内源ROS和激素含量的影响

活性氧(ROS)和植物激素是植物衰老过程中重要的内在或者外在的调控因子.我们发现,相对于离体诱导的衰老过程,在脱落酸(ABA)和乙烯(ethylene)促进的衰老过程中有较多的活性氧积累;在对拟南芥磷脂酶Dδ (PLDδ)缺失型突变体的研究中发现,与野生型相比,突变体在衰老过程中产生较少的活性氧.我们比较了上述两种基因型的离体叶片在离体、ABA和ethylene三种衰老处理下内源的ABA、茉莉酸甲酯(MeJA)、玉米素核苷(Zeatin Riboside,ZR)和吲哚乙酸(IAA)的含量变化,发现每一种激素对上述三种衰老处理的响应模式都很相似.在离体诱导的衰老中,两种基因型拟南芥的内源激素含量没有差异;而在ABA促进的衰老过程中,PLDδ缺失型突变体叶片中的MeJA的含量较低,ZR和IAA含量较高;在乙烯促进的衰老过程中,突变体中的ABA和MeJA的含量较低,ZR和IAA含量较高.上述内源激素的这种变化可能有助于延缓突变体的衰老.     

Effects of Abscisic Acid in Senescence of Garlic Al1tium sativura Scape

Removing the apical cloves from the excised garlic scapes could delay the senescence of scape and decrease the rate of dry matter loss during storage. The ABA content of all the portions of the scapes with apical cloves is decreased as the prolongation of storage period; but its content of all the portions of the scapes with the cloves reaches their peak one after another within the first 6 days of the experiment period. The peak of ABA in the apical cloves appears earliest; the ABA content of any portion of the scapes is lower than that of the cloves, and gradually decreases from upper to lower portions, and the peak of ABA content appears in the sequence as above. Exogenous ABA which is added to the top of the scapes without cloves would simulate the function of the apical cloves in part and accelerates the chlorophyll destruction and senescence of the scapes. No ethylene can be detected by the G. C., in the process of senescence. The authors suggest that ABA is mainly synthesized in the cloves, and then transported into the scapes from there. In the senescence of garlic scapes and in the redistribution of material between the apical cloves and the scapes (the relation between the sink and source), ABA functions as transporting information and promoting senescence but ethylene has not such a function. The senescence of garlic scape could be divided into two stages: first the static phase and second, the active phase.     

细胞分裂素在离体蒜苔内的运转

离体蒜苔饲喂带3H标记的6 — 苄基腺嘌呤(BA)后在暗中25℃下放置,分别在第 3、5、10、15、20天取样,进行放射性物质的分布分析。结果表明：(1) BA能沿着苔茎大量、长距离地上运,并在顶端的珠蒜中积累;(2) BA的这种运转具有很强的向顶极性;(3) 这种运转是一个平缓而稳定的过程,珠蒜中BA的积累与时间成较好的线性关系;(4) 顶端的珠蒜对BA的上运是必不可少的。根据以上结果,本文对蒜苔内BA的运转机理及意义进行了讨论。     

离体蒜苔衰老过程中乙烯产生和纤维素酶活力的变化

自Horton和Osborne(1967)报道衰老、脱落中激素和纤维素酶活力相关性以来,许多实验证明,乙烯和纤维素酶与衰老和脱落有密切关系。关颖谦等(1981)指明离体水稻叶片衰老时,纤维素酶的活力     

The Endodermoid in Garlic Scape: Its Fine Structure and Physiological Function

In garlic scape there is a distinct boundary layer of cells between the cortex and stele. Its fine structure and possible ruction seem to agree with the endodermoid first defined by Esau[7], hence the frame. Lightand electron-microscopic examination and cytochemical test have revealed that this particular laryer is probably responsible for the withdrawal of cellular contents of parenchyma to the peripheral vascular bundles, during a long period of storage the excised withering scape would thoroughly exhaust itself to give rise to the new apical cloves. As already shown, the laticiferous tubes scattered throughout the cortex are always turgid, and their sap is rich of nutrients in variable proportion[3]. Possibility of mobilizing these nutrients by the aid of endodermoid to join in phloem transport also has been discussed.     

大蒜不同品种蒜薹发育的解剖学研究

通过形态观测和石蜡切片法,比较了2个大蒜品种的蒜薹发育和解剖结构。结果表明：（1）“陇县火蒜”比“改良蒜”蒜薹的表皮细胞形状规则,排列致密;角质层较薄;（2）“陇县火蒜”比“改良蒜”蒜薹表面的气孔数量少,但开张度大;分泌细胞出现早、体积大、数量多;维管束数量少、直径小;（3）“陇县火蒜”蒜薹髓细胞卫多边形,髓细胞间隙率小,而“改良蒜”蒜薹的髓细胞呈椭圆形,髓细胞间隙率大。     

Intra and Inter-Cellular Changes in Constitution during the Development of Laticiferous System in Garlic Scape

Systematic investigations, mainly based on electron microscopy, have been conducted on constitutional changes in the laticifer and its adjoining parenchyma during the development of laticiferous system in garlic scape. The laticiferous system of the scape consists of several layers of articulated unbranched latieifers. About half of them are situated 2–3 cell layers below the epidermis, and the rest scattered throughout the cortex (Fig. 23). Latieifer differentiation starts with a thinning out and vacuolation of the dense protoplasm in the latieifer initials (Fig.2), which is followed by gradual degeneration of nuclei, plastids, endoplasmic reticulum, and dictyosomes; and by a sharp diminution of free ribosomes (Figs.3, 4). Remanent and defective forms of some organelles can still be found in the laticifer at the later stage. In spite of these drawbacks, the differentiating laticifer appears to function actively. Its protoplasm is delimited by a distinct plasmalemma (Figs. 3, 4). Its wall is interspersed with pits inclose spacings, to which most plasmodesmata are confined (Figs. 8, 24). The cell interior is packed with vesicles and mitoehondria (Figs. 4, 11, 15). Structurally, the laticifer seems well adapted to material exchange with the adjoining parenchyma. During the sprouting stage of the scape, the laticifer initials enlarge itself or fuse with each other by lateral wall dissolution to extend the diameter; at the same time, the laticifer elongates at an increasingly rapid rate. As a final result, the laticifer can attain 30–50 times the length and 2–3 times. the diameter of the adjoining parenchyma. The electron-dense material which protrudes into the laticifer initial from the parenchyma may be of lysosomal nature and probably concerned with wall dissolution and intracellular lytic processes in latieifer formation (Figs. 5, 7, 10). An excised garlic scape is employed in the observation of mature laticifers, which is always full of sap and is quite turgid. Once the scape is cut open, sap exudes almost exclusively from the cut end of the laticifers at the periphery, which lasts only some seconds. However, if the scape is left aside for a few days, exudation will again take place at the fresh cut end. Unlike the milky juice of many latex plants, the sap exuded from the garlic scape is watery and slightly turbid. The organic solute content is mainly made up of simple sugar and amino acids. It also contains a small amount of proteins and even protoplasmic fragments. Besides, it is worthy to note that decrease in organic solutes in the exudation is closely connected with the degree of exhaustion of cell contents from the withering scape, which is, as has already been shownm the sole agent of supplying materials required for the formation of apical cloves. All the above facts seem to indicate that there exists a loading and unloading process in the latieifer. Our electron micrographs (Figs. 16, 22) give evidence that vesicular transport through plasmodesmata in the pit field is capable of performing such a process: from the parenchyma to the laticifer in loading and from the latter to the former in unloading. The possible role of the laticifers in garlie scape could be a temporary storage of cell contents released successively from the deteriorating parenchyma. The sap content in the laticifer is in full turgidity as a result of loading, and can be readily drawn by unloading if so required. Transcellular cytosis is a term tentatively given by us to designate intercellular transport of sap, solutes, and macromolecular particles in small vesicles, which are formed and packed in one celt, traverse through plasmodesmata and merge into the other; whereas endo and exoeytosis refer to vesicular transport in a single cell only and to its moving in and out of the cell primarily through the plasma membrane, which also takes active part in the formation and dissolution of the vesicle and in the enclosure and release of its content. Transcellular cytosis was first observed by us in the withering parenchyma of an excised garlic scape; and, in the present case, between the latieifer and parenehyma, both being active functionally. As compared with the early notion that intercellular material transport is primarily carried out by secretion and reabsorption of highly degraded products through plasmalemma, transcellular eytosis appears to be a far more efficient means of translocating prefabricated assortment and well packed cargo from one cell into the other.     

Abscisic Acid, Auxin, and Ethylene in Explant Abscission

Experiments with explants of Phaseolus vulgaris L., cv. CanadianWonder, show that abscission and the associated rise in oarboxymethyl-cellulaseactivity in the separation zone are initiated by a peak in ethyleneproduction during senescence of pulvinar tissue distal to thezone. Distal applications of abscisic acid (ABA) induce an earlierpeak in ethylene production, increase cellulase activity, andpromote abscission. ABA is more effective in these ways if treatmentis delayed from 0 to 24 h after excision. With increasing concentrations of ABA the maximum rate of ethylene production is achievedsooner. Indol-3yl-acetic acid (IAA) and ABA are antagonisticin this system and have opposing effects. IAA retards the timeof peak ethylene-production and delays abscission. Explantsmay be retained for long periods without abscinding if incubatedin an ethylene-free atmosphere: the addition of ethylene forany one 24-h period (except the first 24 h after excision) willinduce abscission. The initial period of insensitivity to ethyleneis extended by distal applications of IAA. Ethylene-inducedabscission can be inhibited by IAA applied up to 72 h afterexcision provided the ethylene is not applied first. It is proposedthat abscission in the explant is controlled at two levels:(1) an auxin-dependent stage determining the duration of insensitivityto ethylene; (2) the timing of a rise in ethylene productionin senescing tissue distal to the separation zone. An auxin-ethylenebalance-mechanism at the separation zone is discussed.     

Dormancy in Garlic (Allium sativum L.) cv. Rosado Paraguayo I. Levels of Growth Substances in "Seed Cloves" under Storage

The period of dormancy in "seed cloves" of garlic (Allium sativumL.) under storage was determined by measuring the growth ofthe "first foliar leaf" and its sprouting capacity. The endogenouscontents of growth inhibitors and gibberellins were also measuredby bioassays. Dormancy of garlic bulbs can be characterizedby lack of gibberellin and a presence of moderate contents ofgrowth inhibitors. (Received October 26, 1982; Accepted August 25, 1983)     

CONTROL OF INTERCALARY GROWTH IN THE SCAPE OF GERBERA BY AUXIN AND GIBBERELLIC ACID

With the inflorescence removed, intercalary growth can be maintained in the scape of Gerbera jamesonii by application of gibberellic acid (GA, gibberellin A₃) or indole-3-acetic acid (IAA); the latter usually promotes more rapid and greater elongation than the former because of a greater effect on older tissues. Simultaneous application of the two substances, even when both are at optimal levels, promotes more rapid elongation than either substance alone; in fact, the rate of elongation may equal that of the intact scape. In decapitated scapes (receptacle and involucral bracts removed with the inflorescence), GA and IAA promote cell elongation with reduced or no cell division. In deflowered scapes (receptacle and involucral bracts intact) both GA and IAA promote cell division, as well as cell elongation, so that the pattern of scape elongation is nearly the same as that for intact scapes. Apparently the bracts and receptacle contribute something required for cell division which acts in concert with GA and IAA. Deflowered and decapitated scapes elongate at nearly the same rates initially; thus the rate of elongation does not depend on cell division. The ultimate length of the scape is dependent on cell number and, hence, cell division, since deflowered scapes attain greater lengths than those that are decapitated.