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《中国科学:生命科学》2020,(2)
凯氏带是一种环绕在内皮层细胞径向壁和横向壁上的木质化和木栓化带状增厚结构.凯氏带作为一种保护性屏障,不仅可以调节物质和水分在维管束与皮层细胞之间的渗透性流动,而且在抵御盐胁迫、生物胁迫以及营养物质的选择性吸收等方面也发挥重要作用.随着近年来生物化学分析技术及遗传学研究方法的发展,凯氏带的相关研究取得了极大进展.本文简要概述了凯氏带在植物体内的组织结构、化学组成和发育过程,并重点对凯氏带生理功能、重要调控基因及其相关调控机制等方面的最新进展进行了总结,以期为凯氏带的深入研究和开发利用提供参考. 相似文献
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应用荧光显微技术、傅里叶变换显微红外光谱分析(FTIR)、扫描电镜及X-射线能谱微区分析等手段,对白皮松(Pinus bungeana)子叶、初生叶及2a生针叶内皮层细胞径向壁的显微结构特征、化学成分,以及在叶子横切面上Na和Cl的微区分布进行分析。通过荧光显微观察发现,白皮松子叶内皮层不具凯氏带,而初生叶及2a生针叶均存在凯氏带加厚现象。根据FTIR的检测结果显示:子叶内皮层细胞径向壁不含木栓质或极少,2a生针叶内皮层细胞径向壁木栓质含量高于初生叶。对相应区域的X射线微区分析表明,子叶内皮层对Na和Cl在质外体运输中不起障碍作用,而初生叶与2a生针叶内皮层阻碍Na和Cl以质外体途径进入维管组织。研究结果表明:具凯氏带加厚的内皮层细胞壁中木栓质含量决定其在质外体运输过程中的生理功能。 相似文献
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凯氏带位于被子植物初生根内皮层细胞,环绕细胞1周,是与质膜紧密结合的非极性带状增厚结构。凯氏带作为植物根中离子径向运输障碍,调节离子的质外体吸收途径,迫使土壤中的离子通过内皮层细胞膜,选择性地进入中柱。凯氏带发现于1865年,但直至拟南芥凯氏带蛋白的发现和凯氏带阻滞作用物质基础被揭示,凯氏带的形成机理和功能才逐渐为人们所认知。凯氏带的物质基础为木质素,其形成需要由凯氏带蛋白和受体激酶组成的合成平台。细胞内部的木质素单体经ABCG载体运输到凯氏带的形成区,经ESB1dirigent蛋白、RBOHF氧化酶和PER64过氧化物酶等催化,合成木质素。该文对近年来国内外有关凯氏带形成的分子机制和功能特点方面的研究进展进行综述,为进一步理解和解析凯氏带的形成机理和功能提供参考。 相似文献
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裸子植物和具有少量次生长的双子叶植物根的内皮层细胞通常都具有径向壁和横壁加厚而成的凯氏带结构。但多数单子叶植物和少数双子叶植物(没有次生生长的种类)根的内皮层细胞只有在发育的早期(幼根)具有凯氏带,发育的后期(较老的根)内皮层细胞壁内敷贴了一整层栓质层,随后细胞壁又经过了五面加厚(只有邻接皮层一面的壁没有加厚)或六面加厚(即全部细胞壁都加厚),加厚部分都经过了木质化,因此这时就看不到凯氏带了。由于内皮层细胞内敷贴了一整层栓质层,这类植物根的维管柱似乎被一层不透水的套子所隔开了。实际不然,因为并不是全部内皮层细胞都具有五面或六面加厚的壁,通常有一部分内皮层细胞,就是在根的横切面上靠近木质部角端的那一部分内皮层细胞,仍有未栓质化、未加厚、只有凯氏带的纤维素薄壁,这一部分内皮层细胞 相似文献
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该研究用石蜡切片法比较观察了5种木贼科植物营养器官的内皮层及凯氏带,首次报道了2层内皮层及其凯氏带的形态特征及分布规律,并讨论各种类型的凯氏带及其与厚壁组织的协作防御机制。结果表明:(1)5种木贼的地下茎和根都只有1条凯氏带,其中4种木贼的地上茎有2条凯氏带。(2)木贼类营养器官具有3种凯氏带类型,即2层公共内皮层上各具有1条凯氏带、1层散生内皮层上的1条凯氏带、1层公共内皮层上的1条凯氏带。(3)木贼类地下茎和根都有发达的厚壁组织或致密的表皮。(4)问荆地上茎外侧内皮层具有复合内皮细胞。研究认为,木贼类植物凯氏带数量不能作为分类的依据;地下茎和根虽然只有1条凯氏带,但地下部分都有发达的厚壁组织或(和)与其紧密相连的表皮,推测厚壁组织或(和)表皮可能具有与凯氏带相同的功能;3种类型凯氏带的防御能力由强到弱依次是:2层公共内皮层上的凯氏带 1层散生内皮层上的凯氏带 1层公共内皮层上的凯氏带。 相似文献
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应用冰冻切片、酶解分离、荧光显微技术和傅里叶红外光谱分析(FTIR)等手段,对华山松初生根和针叶内皮层凯氏带进行了分离、显微结构特征和化学成分的比较。研究结果表明:针叶凯氏带的“网格”结构比较整齐,大小较一致,排列也较规则,同时在“网格”的纵向壁上具有明显的初生纹孔场。而初生根凯氏带网状结构的大小、排列均不规则,在其“网格”的纵向壁上的初生纹孔场不明显。根据FTIR的检测结果显示:初生根凯氏带中木栓质和木质素的含量均高于针叶,而纤维素的含量则明显低于针叶;两者细胞壁蛋白的含量基本相同。本文的研究结果为深入探讨植物地下部分和地上部分凯氏带的生理功能提供新的佐证。 相似文献
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植物根中质外体屏障结构和生理功能研究进展 总被引:2,自引:0,他引:2
杨朝东;张霞;刘国锋;张俊卫;包满珠;周志翔 《植物研究》2013,33(1):114-119
综述了近10年来植物根中质外体屏障结构和功能的研究进展。质外体屏障指根中内、外皮层初生壁的凯氏带,或次生壁栓质化和木质化,以及植物体表角质层组成的保护组织,能隔绝水、离子和氧气不能自由进出植物体的屏障结构,具有保护植物体的生理功能。根中凯氏带的分子发育机理研究表明根内皮层类似哺乳动物上皮组织的保护作用。植物根中质外体保证内部各种生理代谢在稳定的内部环境中进行,是植物适应各种逆境的重要屏障结构。根中质外体屏障在植物适应干旱、洪涝灾害、离子胁迫和病虫害的侵袭等方面具有重要作用,在探索适应并修复极端生态环境的植物资源中有广阔的应用前景。 相似文献
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采用在根内生成有色铜沉淀的方法研究大豆(Glycine max)初生根凯氏带对铜离子的通透性。用真空泵抽取浓度为200μmol·L^–1的CuSO4溶液进入根中,然后在重力作用下从根基部灌注400μmol·L^–1的K4[Fe(CN)6]溶液,两种物质在根内相遇即可产生棕色的Cu2[Fe(CN)6]沉淀,根据沉淀的位置来确定铜离子所经过的途径。结果表明:Cu^2+可以穿过内皮层凯氏带,在木质部导管壁以及凯氏带至木质部之间的细胞壁处产生棕色沉淀,侧根发生的部位也产生了大量的沉淀;当抽取K4[Fe(CN)6]溶液后再灌注CuSO4溶液,发现Cu^2+仍然可以穿过凯氏带,并在凯氏带外侧以及外皮层细胞的细胞壁处产生棕色沉淀。研究结果证明凯氏带并不是一个可以完全阻止离子进出的完美屏障。 相似文献
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滇黄芩的解剖学与组织化学研究及其与黄芩的比较 总被引:1,自引:0,他引:1
应用植物解剖学方法和荧光显微技术研究了滇黄芩(Scutellariaalnoena)营养器官的解剖结构。结果表明:根的初生结构中木质部为二原型,凯氏带明显,并开始积累淀粉粒;在茎和叶维管束外有厚壁细胞群分布,较成熟的茎中厚壁细胞群连成一环。通过组织化学方法对黄酮类物质的定位研究表明,多年生根的中柱鞘及韧皮部、茎及叶的表皮和与皮层中的薄壁细胞是黄酮类物质的主要积累场所,其含量根〉茎〉叶。滇黄芩与同属植物黄芩(S.baicalensis)在结构和组化方面的差异主要表现为:黄芩茎中厚壁细胞群分布区域较小且未连成环,细胞壁加厚较不明显,叶中没有厚壁细胞;组化显色结果表明滇黄芩黄酮类物质含量高于黄芩。因此,深入对地方药用资源滇黄芩的研究与开发十分必要。 相似文献
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The structure and development of endodermal Casparian strips in Pinus bungeana needles and roots were studied by scanning electron microscopy and fluorescence microscopy. Primary pit fields (PFs) frequently occurred in radial walls of Casparian strips isolated from needles, whereas PFs were never detected in Casparian strips from roots. Formation of Casparian strips in needles as well as roots started at the outer parts of the radial walls and they finally occupied the entire radial walls of the endodermis. Fourier transform infrared (FTIR) spectroscopy of Casparian strips isolated from roots revealed significant absorption bands characteristic for suberin. However, in Casparian strips of needles, evidence for suberin was rarely detected by FTIR spectroscopy. The apoplastic permeability of Casparian strips in needles and roots was probed by the apoplastic tracers calcofluor and berberine. Casparian strips in roots efficiently blocked the apoplastic transport (AT) of calcofluor and berberine. Casparian strips in needles blocked the AT of calcofluor, but diffusion of berberine was not inhibited and berberine thiocyanate crystals were detectable in the vascular tissue of the needles. From the data presented, it must be concluded that Casparian strips in needles, which are characterized by the absence of suberin, are more solute permeable compared with Casparian strips in roots. 相似文献
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L. Schreiber H.-W. Breiner M. Riederer M. Düggelin R. Guggenheim 《Plant biology (Stuttgart, Germany)》1994,107(5):353-361
The root endodermis of Clivia miniata Reg. was successfully isolated using the cell wall degrading enzymes cellulase and pectinase. The enzymes did not depolymerize those regions of the primary cell walls of anticlinal endodermal root cells where the Casparian strips were located. Since the endodermis of C. miniata roots remained in its primary developmental state over the whole root length, endodermal isolates essentially represented Casparian strips. Thus, sufficient amounts of isolated Casparian strips could be obtained to allow further detailed investigations of the isolates by microscopic, histochemical and analytical methods. Scanning electron microscopy revealed the reticular structure of the Casparian strips completely surrounding the central cylinder of the roots. Whereas in younger parts of the root only the anticlinal cell walls of the endodermis remained intact in the isolates, in older parts of the root the periclinal walls also restricted enzymatic degradation due to the deposition of lignin. Extracts of the isolates with organic solvents did not reveal any wax-like substances which might have been deposited within the cell wall forming a transport barrier, as is the case with cutin and suberin. However, several histochemical and analytical methods (elemental analysis and FTIR spectroscopy) showed that the chemical nature of the Casparian strips of C. miniata roots can definitely be a lignified cell wall. These findings are in complete agreement with studies carried out at the beginning of this century on the chemical nature of the Casparian strips of several other plant species. The implications of these results concerning apoplasmatic transport of solutes and water across Casparian strips are discussed. 相似文献
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Casparian strips in needles of Pinus bungeana: isolation and chemical characterization 总被引:6,自引:0,他引:6
By using cell wall degrading enzymes, Casparian strips were for the first time isolated from Pinus bungeana needle endodermis. They appeared as a fine network, similar to those isolated from roots. Fourier transform infrared spectroscopic analysis provided evidence that the Casparian strips were impregnated with lignin, suberin, cellulose and cell wall proteins. 相似文献
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The root system is particularly affected by unfavourable conditions because it is in direct contact with the soil environment. Casparian strips, a specialised structure deposited in anticlinal walls, are characterised by the impregnation of the primary wall pores with lignin and suberin. The Casparian strips in the endo- and exodermis of vascular plant roots appear to play an important role in preventing the non-selective apoplastic bypass of salts into the stele along the apoplast under salt stress. However, only a few investigations have examined the deposition and function of these apoplastic barriers in response to salt stress in higher plants. 相似文献
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John M. Byrne Kathleen A. Collins Pamela F. Cashau Louis H. Aung 《American journal of botany》1975,62(7):731-737
Tomato seedlings five through ten days old were used for this investigation. Adventitious roots were initiated from the pericycle of the tomato hypocotyl. The position of adventitious root development was irregular in the rhizogenic hypocotyl; however, the cellular pattern of individual root development was very regular. Four layers of pericycle derivatives participated in root histogenesis and a bi- or triseriate endodermal cover was derived from the endodermis. Fluorescent microscopy showed that Casparian strips on the meristematic endodermal cell walls were not removed biochemically but were displaced around the root primordium by anticlinal divisions and cell enlargement. Casparian strips were not synthesized by endodermal cover cells. The emergent root had a typical three tiered or closed pattern of apical organization, and quiescent centers were present in all emergent roots longer than 0.5–0.6 cm. 相似文献