共查询到20条相似文献，搜索用时 926 毫秒
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为探讨人参化感物质的作用机制,采用石蜡切片技术研究人参化感物质对其幼苗根尖解剖结构的影响。利用人参化感物质活性组分培养其幼苗96 h后,取其根尖,进行石蜡切片,采用番红—固绿染色。结果表明:化感物质组分处理后的人参幼苗根尖几个功能部位的细胞大小及排列发生了明显的变化,处理后的幼苗根尖明显变粗,细胞间隙加大,表皮层细胞部分脱落,顶端分生组织和根冠的细胞混乱,这种效应随着处理浓度的增加而增强,且在浓度为40 g·mL-1处理时,一部分顶端分生组织细胞的细胞壁形态异常甚至破裂,中柱鞘细胞明显膨胀。 相似文献
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杜仲根组织分化的观察与分析 总被引：4，自引：0，他引：4
杜仲(Eucommia ulmoides Oliv.)的根为主根系。根尖顶端原始细胞分旱层为中柱原、皮层原和表皮-根冠原。整个根尖基本生长速率,自原始细胞向基端320μm前后最大,1200μm处下降到最小。原始细胞最初无分化,向基100μm处开始分化为初生分生组织,210μm处中柱鞘开始分化,500μm处出现最早筛管分子,620μm处出现最早导管分子,1300μm处表皮成熟形成根毛,2500μm处初生结构分化完成。内皮层凯氏带不明显,中柱鞘由一层细胞构成。木质部束多数为二原型,另外有三原、四原和五原型。韧皮部薄壁细胞形成许多橡胶丝。初生结构形成后,维管形成层即活动,产生次生维管组织,同时皮层第二层细胞分裂形成第一次的木栓形成层,产生周皮。次生韧皮部的轴向系统中也分化产生橡胶丝。侧根原基由木质部放射棱顶端中柱鞘细胞发生,根尖及成熟结构与主根相同。 相似文献
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油松针叶束离体培养下器官建成的解剖学研究 总被引：7，自引：0，他引：7
油松针叶束经离体培养形成幼苗的整个过程，可划分为三个阶段，即愈伤组织的起源与形成；根原基的发生和不定根的形成；芽的萌动与生长。发生在针叶束切口上的愈伤组织起源于形成层和韧皮部的薄壁细胞，经脱分化恢复分生组织的生理机能，并进行分裂活动形成愈伤组织。根原基主要是从愈伤组织内发生，属于愈伤组织生根类型。在愈伤组织内分化出来的分生组织结节和维管组织结节，经单向极性分裂活动形成根原基，并继续生长突破愈伤组织成为不定根。芽在愈伤组织出现后起动，生长锥进行缓慢的分裂活动，由扁圆形芽体变为长圆形，并形成初生叶原基与幼叶紧包生长锥。移植后芽生长迅速，长出数枚窄条状初生叶，不久即抽梢。 相似文献
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Murray JD Karas BJ Sato S Tabata S Amyot L Szczyglowski K 《Science (New York, N.Y.)》2007,315(5808):101-104
In legumes, Nod-factor signaling by rhizobia initiates the development of the nitrogen-fixing nodule symbiosis, but the direct cell division stimulus that brings about nodule primordia inception in the root cortex remains obscure. We showed that Lotus japonicus plants homozygous for a mutation in the HYPERINFECTED 1 (HIT1) locus exhibit abundant infection-thread formation but fail to initiate timely cortical cell divisions in response to rhizobial signaling. We demonstrated that the corresponding gene encodes a cytokinin receptor that is required for the activation of the nodule inception regulator Nin and nodule organogenesis. 相似文献
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Mähönen AP Bishopp A Higuchi M Nieminen KM Kinoshita K Törmäkangas K Ikeda Y Oka A Kakimoto T Helariutta Y 《Science (New York, N.Y.)》2006,311(5757):94-98
The cell lineages that form the transporting tissues (xylem and phloem) and the intervening pluripotent procambial tissue originate from stem cells near the root tip. We demonstrate that in Arabidopsis, cytokinin phytohormones negatively regulate protoxylem specification. AHP6, an inhibitory pseudophosphotransfer protein, counteracts cytokinin signaling, allowing protoxylem formation. Conversely, cytokinin signaling negatively regulates the spatial domain of AHP6 expression. Thus, by controlling the identity of cell lineages, the reciprocal interaction of cytokinin signaling and its spatially specific modulator regulates proliferation and differentiation of cell lineages during vascular development, demonstrating a previously unrecognized regulatory circuit underlying meristem organization. 相似文献
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几种中国兰种子试管培养根状茎发生的研究 总被引：18，自引：0，他引：18
对蕙兰和墨兰的种子进行解剖学观察,可以看到种皮由一层透明的细胞组成,种胚为发育不完全的球形胚,胚内不含淀粉,仅含脂类作为储存营养物质．试管培养条件下,球形胚顶端细胞分裂,胚体积增大,胀破种皮,形成类原球茎．其顶端分生组织细胞继续分裂,形成根状茎．在激素诱导下,根状茎的表皮和皮层细胞可分裂形成侧生分生组织．然后顶生和侧生分生组织分化出叶原基,表皮和皮层细胞分化出不定根．在种子萌发成苗的过程中,脂类逐渐消失,蛋白质在分生组织细胞中含量较多,淀粉粒多分布在薄壁细胞中,与形态发生有密切关系． 相似文献
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沙棘微扦插不定根发生的形态解剖学研究 总被引：3，自引：0，他引：3
利用石蜡切片法对沙棘微扦插不定根的发生进行形态解剖学研究。结果表明:沙棘属于诱导型生根,观察到其不定根原基起源于2个区域,一部分根原基起源于维管形成层细胞,另一部分起源于韧皮部薄壁细胞区域。沙棘不定根原基继续发育时,一部分沿射线向外生长,另一部分向外生长的同时会与茎段的髓连接起来,这种现象在其他树种中尚未发现。沙棘插穗不定根的发生整体上可分为4个阶段:1）维管形成层细胞和韧皮部薄壁细胞分裂出一些排列紧密、细胞质浓、具有分生组织特点的薄壁细胞团;2）新形成的薄壁细胞团不断分裂并且脱分化,形成具有很强分生能力的不定根原基发端细胞;3）根原基发端细胞继续分裂,沿着射线向远离轴心的方向伸展,从而形成根原基;4）根原基穿过韧皮射线和皮层,向外继续朝皮孔方向发展,最终从皮孔伸出形成不定根,不定根伸出皮孔前内部维管系统发育完善并与茎部维管系统相连接。 相似文献
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The shoot apical meristem (SAM) is a collection of stem cells that resides at the tip of each shoot and provides the cells of the shoot. It is divided into functional regions. The central zone (CZ) at the tip of the meristem is the domain of expression of the CLAVATA3 (CLV3) gene, encoding a putative ligand for a transmembrane receptor kinase, CLAVATA1, active in cells of the rib meristem (RM), located just below the CZ. We show here that CLV3 restricts its own domain of expression (the CZ) by preventing differentiation of peripheral zone cells (PZ), which surround the CZ, into CZ cells and restricts overall SAM size by a separate, long-range effect on cell division rate. 相似文献
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Stomata regulate gas exchange and are distributed across the leaf epidermis with characteristic spacing. Arabidopsis stomata are produced by asymmetric cell divisions. Mutations in the gene TOO MANY MOUTHS (TMM) disrupt patterning by randomizing the plane of formative asymmetric divisions and by permitting ectopic divisions. TMM encodes a leucine-rich repeat-containing receptor-like protein expressed in proliferative postprotodermal cells. TMM appears to function in a position-dependent signaling pathway that controls the plane of patterning divisions as well as the balance between stem cell renewal and differentiation in stomatal and epidermal development. 相似文献
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黑穗醋栗的“薄皮”和“厚皮”品种的根端结构为“封闭型”,以“体—帽”式的分裂增加根端分生组织区域纵列的细胞。在不同品种或同一品种的不同根系中,初生木质部有不同的原型:二原型、三原型和四原型。在不定根的周皮上发现有少数皮孔,位于较宽射线的上面或一侧。周皮的内侧有薄壁组织细胞层。“薄皮”黑穗醋栗的薄壁组织细胞层内有“分泌结构”存在。在不定根的皮层、薄壁组织细胞层、韧皮薄壁细胞和射线薄壁细胞中均富含贮藏物质和结晶。在2原型和4原型的根中,发现侧根正对着原生木质部的位置,也有在原生木质部和原生韧皮部之间的部位,由中柱鞘细胞脱分化再分化而成。 相似文献
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Developmental Characteristics and Cinnamic Acid Resistance of Root Border Cells in Cucumber and Figleaf Gourd Seedlings 总被引：1，自引：0，他引：1
QIAO Yong-xu ZHANG Yong-ping ZHANG Hong-xin TIAN Yong-qiang GAO Li-hong 《农业科学学报》2013,12(11):2065-2073
Root border cells （RBCs） originate from the root tip epidermis and surround the root apices. In this study, we evaluated the developmental characteristics and the roles of RBCs in protection of root apices of cucumber and ifgleaf gourd seedlings from CA toxicity. The formation of RBCs and the emergence of the root tip occurred almost simultaneously in root apices of cucumber and ifgleaf gourd seedlings. CA ranging from 0 to 0.25 mol L-1 inhibited root elongation and decreased root cell viability in the root tip, moreover the inhibitory effects of CA were more signiifcant in the CA-sensitive cucumber than in the CA-tolerant ifgleaf gourd. Removal of RBCs from root tips led to more severe CA induced inhibition of root elongation and decline in root cell viability. Increasing CA levels and treatment time decreased the relative viability of attached and detached RBCs. CA also induced a thicker mucilage layer surrounding attached RBCs of both species. Additionally, a signiifcantly higher relative cell viability of attached RBCs and thicker mucilage layers were observed in ifgleaf gourd. These results suggest that RBCs play an important role in protecting root tips from CA toxicity. 相似文献
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van Brussel AA Bakhuizen R van Spronsen PC Spaink HP Tak T Lugtenberg BJ Kijne JW 《Science (New York, N.Y.)》1992,257(5066):70-72
Root nodules of leguminous plants are symbiotic organs in which Rhizobium bacteria fix nitrogen. Their formation requires the induction of a nodule meristem and the formation of a tubular structure, the infection thread, through which the rhizobia reach the nodule primordium. In the Rhizobium host plants pea and vetch, pre-infection thread structures always preceded the formation of infection threads. These structures consisted of cytoplasmic bridges traversing the central vacuole of outer cortical root cells, aligned in radial rows. In vetch, the site of the infection thread was determined by the plant rather than by the invading rhizobia. Like nodule primordia, pre-infection thread structures could be induced in the absence of rhizobia provided that mitogenic lipo-oligosaccharides produced by Rhizobium leguminosarum biovar viciae were added to the plant. In this case, cells in the two outer cortical cell layers containing cytoplasmic bridges may have formed root hairs. A common morphogenetic pathway may be shared in the formation of root hairs and infection threads. 相似文献
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为了探究秋水仙素对肇东苜蓿根尖细胞染色体的影响,利用不同浓度的秋水仙素(0.01%、0.05%、0.10%、0.15%和0.20%)以及处理时间(12、24、36和48h)分别对肇东苜蓿根尖细胞进行诱导,观察肇东苜蓿根尖细胞染色体、细胞中期分裂指数和细胞加倍指数的变化。结果表明:秋水仙素诱导了肇东苜蓿根尖细胞染色体的变异,细胞内染色体加倍,数目不等(32、64及128条);在时间与浓度互作方面,秋水仙素溶液浓度为0.15%时处理肇东苜蓿根尖12h,使细胞中期分裂指数达到最大值18.51%;利用浓度为0.10%的秋水仙素处理24h,细胞加倍指数达到最高值11.57%。 相似文献
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The construction of multicellular organisms depends on stem cells-cells that can both regenerate and produce daughter cells that undergo differentiation. Here, we show that the gaseous messenger ethylene modulates cell division in the cells of the quiescent center, which act as a source of stem cells in the seedling root. The cells formed through these ethylene-induced divisions express quiescent center-specific genes and can repress differentiation of surrounding initial cells, showing that quiescence is not required for these cells to signal to adjacent stem cells. We propose that ethylene is part of a signaling pathway that modulates cell division in the quiescent center in the stem cell niche during the postembryonic development of the root system. 相似文献
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高等植物的最终形态主要依赖于茎端分生组织的发育调控,拟南芥CLV/WUS途径是茎端分生组织最重要的调控机制之一。CLV途径促进器官发生,WUS途径诱导分生组织细胞增殖,它们构成了负反馈调节环,保证了拟南芥分生组织的正常增殖与分化。利用突变体基因克隆和系统发育比较,证实了CLV和WUS的同源基因也存在于以水稻和玉米为代表的禾本科作物中,说明CLV/WUS信号途径在禾本科作物中很可能是保守的。由于禾本科作物茎端分生组织的发育最终关系到作物的产量和品质,因此,深入研究禾本科作物的CLV/WUS信号途径将有助于禾本科作物的遗传改良。 相似文献