构树剥皮再生的研究

构树[Broussonetia papyrifera(L.)Vent.]在芽展开后的整个生长季节中,其茎部经过大面积环剥,都能再生新皮,环剥后初期,愈伤组织都由近暴露面的射线细胞产生,稍后,其它未成熟木质部细胞也参加愈伤组织的形成,这些愈伤组织一般在靠近表面处都可发生木栓形成层,而在里面近中间处发生维管形成层,新发生的维管形成层正常地向外分化出韧皮部,内分化出木质部,不过,在5月下旬至8月上旬剥皮的,由于气温较高,膜内湿度较大,在包裹塑料薄膜期间,新产生的周皮表面往往出现不断分离的疏松层,待揭去塑料薄膜后,才可迅速形成正常的周皮。     

构树剥皮再生的研究

构树[Broussonetia papyrifera(L.)Vent.]在芽展开后的整个生长季节中,其茎部经过大面积环剥,都能再生新皮,环剥后初期,愈伤组织都由近暴露面的射线细胞产生,稍后,其它未成熟木质部细胞也参加愈伤组织的形成,这些愈伤组织一般在靠近表面处都可发生木栓形成层,而在里面近中间处发生维管形成层,新发生的维管形成层正常地向外分化出韧皮部,内分化出木质部,不过,在5月下旬至8月上旬剥皮的,由于气温较高,膜内湿度较大,在包裹塑料薄膜期间,新产生的周皮表面往往出现不断分离的疏松层,待揭去塑料薄膜后,才可迅速形成正常的周皮。     

中药秦艽根内中柱裂分的发育解剖学研究

通过发育解剖学研究表明,秦艽根的初生结构正常,初生木质部四原型。次生生长早期阶段也是正常的,但天以后的次生生长过程中,由于木质部内部分薄壁细胞的分裂,且迅速 化成异常形成层细胞,并与原维管形成层相连,从而形成多个新的形成层环,将木质部柱分为几个子木质部。     

乌拉尔甘草根与根状茎发育解剖学研究

应用常规石蜡切片方法,对乌拉尔甘草根和根状茎的结构及其发育进程进行研究.结果显示:(1)乌拉尔甘草根的发育包括原分生组织、初生分生组织、初生生长和次生生长4个发育阶段.原分生组织由3层原始细胞组成,具有典型分生组织细胞的特征;初生分生组织由根冠原、表皮原、皮层原和中柱原组成;初生结构包括表皮、皮层和中柱,初生木质部为4原型,偶见3原型,内皮层细胞具凯氏带;次生生长依靠维管形成层和木栓形成层活动完成,维管形成层源于初生木质部和初生韧皮部之间的薄壁细胞,而木栓形成层由中柱鞘细胞脱分化产生;次生结构由次生维管组织和周皮共同组成,根中央不具髓.(2)根状茎发育过程与地上茎类似,包括原分生组织、初生分生组织、初生生长和次生生长4个发育阶段.原生分生组织由原套和原体组成,其衍生细胞分化成由原表皮、基本分生组织和原形成层组成的初生分生组织;初生结构包括表皮、皮层、外韧维管束、髓和髓射线,维管束呈环形排列;位于维管束中的原形成层细胞恢复活动产生次生木质部和次生韧皮部,束间形成层产生射线细胞;靠近维管束内侧的皮层薄壁组织细胞脱分化产生木栓形成层,以后形成周皮.周皮、次生维管束、射线和髓共同构成根状茎的次生结构.     

红皮云杉茎的解剖结构与插条不定根形成的研究

１９９２年７－８月定时固定红皮云杉插条基部材料于ＦＡＡ液中,石蜡制片法室内解剖研究不定根的发生。结果表明：红皮云杉插条诱发根原基的来源有两种途径。一种是愈伤组织生根型,在愈伤组织的再生形成层处,或茎的维管形成层诱发根原基;另一种是非愈伤组织生根型,在插条切口处的维管形成层、皮层或初生木质部与次生木质部间的薄壁组织较深的部位,直接产生纵向不定根原始体,有的在距离切口０．１－０．５ｃｍ以上茎的维管形成层,维管形成层与木射线的交界处及叶隙等薄壁组织产生径向不定根。不同个体间产生的不定根数量及发育的早晚差异较大。     

维管形成层分化的研究

种子植物的生长主要由于顶端分生组织和侧生分生组织的作用,特别是木本植物(例如通常所说的树木)的长粗、长大,基本上是侧生分生组织的维管形成层的活动结果。这些木本植物的维管形成层(简称形成层)向外分化出次生韧皮部,向内形成次生木质部。这种分化形成,界线明显,容易看到它的衍生细胞。     

风花菜根异常次生结构的解剖学观察

利用光镜观察了风花菜（Rorippa islandica (Oed.)Borb.）的根的发育过程中的解剖结构的变化,发现风花菜根具有异常次生结构,第一年早期次生结构中,在导管周围形成额外形成层并由额外形成层向内外分裂形成大量的薄壁组织,从而使根快速增粗,在根的横切面上,导管分散在薄壁组织当中。第一年晚期的次生结构中,由木质部中薄壁组织细胞反分化形成额外形成层,许多分散的额外形成层片段连接形成形成层环,形成层环向内向外分裂形成三生木质部及三生韧皮部,从而构成三生维管组织环,三生维管组织环形成方向由外向内,可以形成多环。第二年风花菜的韧皮部以及皮层中的薄壁组织反分化形成额外形成层,并且由额外形成层片段连接形成额外形成层环,进而分裂形成三生维管组织环,而且在皮层中可以形成多层,形成的方向为由内向外。风花菜根不同发育时期的异常次生结构是与其生理活动相适应的。     

结球甘蓝离体下胚轴愈伤组织的维管组织及管状分子

结球甘蓝离体下胚轴培养初期,在切口较深层发现的维管组织结节,是由外植体维管组织衍化的。愈伤维管组织既可由愈伤薄壁细胞分化,也可由愈伤形成层分化。愈伤形成层向内分化导管分子,向外没有发现筛分子的分化。愈伤维管组织有不同的形态,起初常各不相连,后和外植体维管组织衔接。芽的再生起初和愈伤维管组织没有直接的联系,后原形成层自上而下分化,逐渐与愈伤维管组织相连接。不定根发生于维管组织结节的单向极性分化,始终     

杂种鹅掌楸插穗不定根发生与发育的解剖学观察

从解剖学角度着手,对杂种鹅掌楸〔Liriodendronchinense(Hemsl.)Sarg.×L.tulipiferaL.〕扦插过程中不定根的发生发育进行了研究。结果表明:杂种鹅掌楸插穗内未发现潜伏根原基。扦插后,不定根原基起源于维管形成层区,属于诱导生根类型。维管形成层恢复活动后,在不定根发生的部位附近形成1个明显的多薄壁细胞区域,在此区域不定根较容易发生。愈伤组织内没有发现根原基,愈伤组织在发育的过程中,内部细胞部分分化,并形成不规则的输导组织。大量的愈伤组织对不定根的发生有较强的抑制作用。杂种鹅掌楸插穗上不定根的发生可分为4个阶段:(1)维管形成层恢复活动,分裂出多层薄壁细胞;(2)维管形成层及附近的薄壁细胞脱分化,形成不定根原基发端细胞;(3)根原基发端细胞不断分裂成具有方向性的根原基,根原基穿过韧皮射线和皮层,向皮孔或下切口方向发展;(4)不定根从皮孔或下切口伸出,其内部的维管系统开始发育。     

毛青藤茎的发育解剖学研究

毛青藤茎顶端的原生分生组织由原套和原体组成,其行生细胞形成初生分生组织──原表皮、原形成层和基本分生组织。初生分生组织的衍生细胞分化形成茎的初生结构,包括表皮、皮层、维管束和髓。随着茎的继续发育,维管形成层开始活动,由束中形成层产生次生韧皮部和次生木质部分子,而束间形成层仅产生薄壁组织细胞形成宽的射线。在原生韧皮部筛管分化成熟的过程中,韧应部外方仍保留1—2层原形成层细胞,以后,它们分裂为多层纤维原始细胞,在次生结构形成时,这些细胞的细胞壁加厚,形成初生初皮纤维。茎始终未产生用皮。     

Studies on Regeneration after Girdling of Broussonetia papyrifera (L.) Vent

The trunk of Broussonetia payrifera (L.) Vent. following an extensive length of completegirdling could regenerate new bark in the entire growing season after bud-sprouting. Severaldays after girdling, most of ray cells near the surface dilated and proliferated outward to formcallus. Then, other immature xylem cells rehabilitated the ability of cell division and tookpart in the formation of callus Later, a cork cambium developed near the surface of thecallus and a cambium near the middle part of the callus. The newly formed cambium cannormally produce phloem outward and xylem inward. However, when the girdled trunk waswrapped up with a transparent plastic shee during the growing period from late May to earlyAugust causing high temperature and humidity inside the wrapping sheet, the surface of peridem often produced loose sloughy cell layers that could regain it’s normal structure after unwrapping the sheet.     

Comparative Studies on Differentiation of Regenerated Tissue in Broussonetia papyrifera

This paper describes the differentiation process of regenerated tissue after ordinary girdling or after removal of a section of xylem from the stem, and the disparity in differentiation of the regenerated tissues after being differently treateds in Broussonetia papyrifera. After ordinary girdling for 3–4 weeks, new bark regenerated in the xylem. During the process of rind' formation, many specks of meristematic tissue were formed in the callus, from which vascular tissue clusters were developed. In addition, the new periderm appeared almost at the same time as the new vascular cambium was seen. When a section of xylem was removed from the stem, numerous calli developed rapidly on the inner surface of the bark. Meanwhile, the vascular cambium appeared in the immature phloem. Soon after, discontinued meristematic tissue bands also occurred in the callus. These meristematic tissues then connected with each other to form a concave oblate cambial ring which developed xylem inward and phloem outward. About 2–3 weeks later, the concave oblate trunk grew lengthwisely connecting with the upper anct lower portions of the normal stem. By then, the tree continued to grow. The inner surface tissue of the bark, after the xylem was removed, differentiated about one week earlier than the tissue on the surface of the xylem after girdling.     

Anatomical Studies of Regeneration after Ringing of Eucommia ulmoides

The trunk of Eucommia ulmoides Oliv. following ringing about one meter in length, could regenerate new bark without significantly affecting the tree growth. Such regeneration process differed from that following partial stripping in other trees as has been reported previously. After ringing in Eucommia ulmoides, there was primarily a proliferation of xylary mother cells and partly remained cambium cells forming a cork layer which led to the establishmant of a more or less normal complete periderm. At the same time the xylary ray cells near the surface dilated and proliferated until they extended across in continuity with the neighbor rays. No callus formation by the rays emerged from the surface was observed. Among the ray cells following multiplication, some immature xylary elements were also visible. Simultaneously, some immature xylary elements lying internal to region of the dilated and coalesced ray cells gradually transformed into new cambium. Due to the fact that initially part of the xylary ray cells was not completely differentiated, it seemed that some of the remained xylary rays separated the newly formed cambium zone into many segments. Three to four months after ringing, new cambium activity proceeded periclinally so as to establish a complete ring of cambium zone. Subsequent differentiation of newly formed cambium followed the normal pattern of vascular tissue development in this plant.     

Histogenesis of Xylem of Eucommia ulmoides Cultured in Vitro

Following a complete ringing of the main stem of Eucommia ulmoides Oliv. regeneration of normal new bark has been observed as a subsequence of repeated partial differentiation of the immature xylem into cambium. The immature xylem, when cultured in vitro, showed production of callus tissue from the ray cells. After 15–30 days of continuous culture, meristematic tissue appeared as a discontinuous and more or less regularly arranged.zone was visible within the callus tissue. However, the meristematic cells, unlike the elongated fusif0rm initial cells, are isometric in shape. This meristem differentiated into tracheids centripetally. Nevertheless, no centrifugal differentiation into phloem was evidenced. The vascular tissues were ultimately degenerated after 6 months cultured in vitro.     

杜仲次生木质部分化和脱分化过程中酸性磷酸酶的超微细胞化学定位

杜仲（EucommiaulmoidesOliv．）次生木质部分化过程中,在形成层刚衍生的木薄壁细胞中,酸性磷酸酶（APase）主要分布于核膜边缘和高尔基体;在分化程度较高的木薄壁细胞中,APase散布于整个核中,进而,在各种细胞器残体上聚集;在成熟的木薄壁细胞中,APase沿细胞壁内侧分布。在未成熟导管分子中,核、质膜及纹孔上明显存在APase聚集,进而,核解体;在即将分化成熟的导管分子中,APase主要集中于初生壁;在已分化成熟的导管分子中,APase集中于次生壁。脱分化过程中,只在细胞质中可见分散的APase活性,而细胞核和细胞壁上未见此酶的分布;更深层的即将分化成熟和已分化成熟的导管分子,未见有细胞分裂,其上APase的分布与剥皮前相同。通过比较分化和脱分化过程中APase的分布,推测不同的APase同工酶可能分别参与了次生木质部细胞程序性死亡过程中原生质体的解体和次生壁的建成。APase的聚集程度可能是决定细胞能否脱分化的一个重要特征。     

The origin and development of vascular cambium in girdled stems ofEucommia ulmoides Oliv.

We conducted anatomical studies of girdled stems ofEucommia ulmoides at various developmental stages to elucidate the origin and development of callus and the vascular cambium. In the transverse view, ray initial cells in the cambial zone began to divide both periclinally and anticlinally 2 d after girdling. Fusiform initial cells started to enlarge at 3 d, then gradually proliferated via periclinal divisions. Thus, the callus was derived from the ray initial cells of the cambial zone as well as from fusiform initial cells. In the tangential view, callus cells derived from ray initial cells were short while those from fusiform initial cells were long, thereby producing a heterogeneous structure. However, the fusiform initial cells underwent transverse divisions 10 d after girdling, which resulted in shorter cells and a homogeneous callus structure. Afterward, some short cells divided transversely while others elongated, so that a heterogeneous form was regained. Finally, the vascular meristem that was girdled early in its development redifferentiated from short and long cells in the callus. The long cells developed into fusiform initials, with the short ones becoming ray initials.     

Molecular features of secondary vascular tissue regeneration after bark girdling in Populus

Regeneration is a common strategy for plants to repair damage to their tissue after attacks from other organisms or physical assaults. However, how differentiating cells acquire regenerative competence and rebuild the pattern of new tissues remains largely unknown. Using anatomical observation and microarray analysis, we investigated the morphological process and molecular features of secondary vascular tissue regeneration after bark girdling in trees. After bark girdling, new phloem and cambium regenerate from differentiating xylem cells and rebuild secondary vascular tissue pattern within 1 month. Differentiating xylem cells acquire regenerative competence through epigenetic regulation and cell cycle re-entry. The xylem developmental program was blocked, whereas the phloem or cambium program was activated, resulting in the secondary vascular tissue pattern re-establishment. Phytohormones play important roles in vascular tissue regeneration. We propose a model describing the molecular features of secondary vascular tissue regeneration after bark girdling in trees. It provides information for understanding mechanisms of tissue regeneration and pattern formation of the secondary vascular tissues in plants.     

Seasonal variation in the ultrastructure of the cambium in young stems of willow (Salix viminalis) in relation to phenology

The growth period of Salix viminalis L. (clone 683) plants near Stockholm, Sweden, (59.5°N, 18.3°E) started in April with flowering and ended in October with abscission of the shoot tips. Cell divisions in the vascular cambium started almost two months before sprouting and ceased at about the same time as the elongation growth of the shoots. Phloem cells were apparently produced before flowering, while new xylem production started at the time of flushing. Cytodifferentiation in immature xylem continued until November. Thick-walled cells with protoplasm were observed adjacent to xylem mother cells in the cambium during the winter. The number of radially arranged cells in the cambial zone increased from 3–4 during dormancy to about 18 during the mitotic maximum in July. Seasonal variation was apparent in vacuolization, wall thickness and presence of storage material in the cells. Lipid bodies and protein bodies occurred in both fusiform and ray initials, while starch was observed in ray initials, ray cells and in the phloem. In September the ultrastructure of the cambium showed anatomical features characteristic for both active and dormant cells. Dictyosomes with vesicles and rough ER were present in thick-walled cells that contained lipid bodies and starch granules. Nuclear divisions in the cambium ended in October.     

Phloem transdifferentiation from immature xylem cells during bark regeneration after girdling in Eucommia ulmoides Oliv

Eucommia ulmoides Oliv. (Eucommiaceae), a traditional Chinesemedicinal plant, was used to study phloem cell differentiationduring bark regeneration after girdling on a large scale. Hereit is shown that new sieve elements (SEs) appeared in the regeneratedtissues before the formation of wound cambium during bark regenerationafter girdling, and they could originate from the transdifferentiationof immature/differentiating axial xylem cells left on the trunk.Assays of water-cultured twigs revealed that girdling blockedsucrose transport until the formation of new SEs, and the regenerationof the functional SEs was not dependent on the substance providedby the axis system outside the girdled areas, while exogenousindole acetic acid (IAA) applied on the wound surface acceleratedSE differentiation. The experiments suggest that the immaturexylem cells can transdifferentiate into phloem cells under certainconditions, which means xylem and phloem cells might share someidentical features at the beginning of their differentiationpathway. This study also showed that the bark regeneration systemcould provide a novel method for studying xylem and phloem celldifferentiation. Key words: Bark regeneration, Eucommia ulmoides Oliv., immature xylem cells, sieve elements, transdifferentiation Received 19 November 2007; Revised 23 January 2008 Accepted 24 January 2008     

Stem anatomy and development of successive cambia in Hebanthe eriantha (Poir.) Pedersen: a neotropical climbing species of the Amaranthaceae

Hebanthe eriantha (Poir.) Pedersen, a climbing species of the Amaranthaceae increases in stem thickness by forming successive cambia. The family is dominated by herbaceous species and is constantly under discussion due to its disputed nature of the meristem. In the young stem small alternate segments of vascular cambium cease to divide and new arc of cambium initiates outside to it. The newly formed arcs connect with pre-existing alternate segments of cambium to complete the ring. On the contrary, in thick stems, instead of small segments, complete ring of cambium is replaced by new one. These new alternate segments/cambia originate from the parenchyma cells located outside to the phloem produced by previous cambium. Cambium is storied and exclusively composed of fusiform initials while ray cells remain absent at least in the early part of the secondary growth. However, large heterocellular rays are observed in 15-mm diameter stems but their frequency is much lower. In some of the rays, ray cells become meristematic and differentiate into radially arranged xylem and phloem elements. In fully grown plants, stems are composed of several successive rings of secondary xylem alternating with secondary phloem. Secondary xylem is diffuse-porous and composed of vessels, fibres, axial parenchyma while exceptionally large rays are observed only in the outermost regions of thick stems. Vessel diameter increases progressively from the centre towards the periphery of stems. Although the origin of successive cambia and composition of secondary xylem of H. eriantha remains similar to other herbaceous members of Amaranthaceae, the occurrence of relatively wider and thick-walled vessels and large rays in fully grown plants is characteristic to climbing habit.