Ontogeny of the protophloem fibers and secondary xylem fibers within the stem of Coleus. I. A light microscope study

1975 ◽  
Vol 53 (16) ◽  
pp. 1658-1671 ◽  
Author(s):  
Thompson Demetrio Pizzolato ◽  
Charles Heimsch
Keyword(s):  
Secondary Xylem ◽  
Wood Fiber ◽  
Sieve Tube ◽  
Wall Thickening ◽  
Intrusive Growth ◽  
Companion Cells ◽  
Secondary Wall Thickening ◽  
Phloem Fibers ◽  
Single Nucleus ◽  
Xylem Fibers

The maturation of the primary phloem fibers and secondary xylem fibers in Coleus stems was studied using Nomarski optics. The phloem fiber initials differentiate from the procambium at the same time as the earliest sieve-tube elements and companion cells. Lateral expansion and intrusive growth by the fiber primordia, which obliterate most of the other primary phloem cells, continue until the young fibers begin forming secondary walls. The single nucleus divides a few times and cytokinesis occurs by the formation of septa. After a few septa are formed, cytokinesis may not follow additional mitoses. The cell wall continues to thicken, and the septa may develop secondary layers. Although there is some nuclear degeneration, the fibers remain alive after maturity. During their maturation small groups of protophloem fibers in the corner sectors become consolidated into fewer, larger groups by the crushing of intervening cells. The maturation of xylem fibers is more rapid than that of phloem fibers. Secondary wall thickening begins in the second cell from the cambium. After wall thickening ceases, the single fusiform nucleus undergoes mitosis followed by septum formation. The septate wood fiber is alive at maturity.

scholarly journals Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger and Brasilicereus Backeberg

2007 ◽  
Vol 21 (4) ◽  
pp. 813-822 ◽  
Author(s):  
Patricia Soffiatti ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Sieve Tube ◽  
Vascular Bundles ◽  
Campos Rupestres ◽  
Espinhaço Range ◽  
Diagnostic Characters ◽  
Bordered Pits ◽  
Companion Cells ◽  
Southern Bahia ◽  
Perforation Plates

(Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaço Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii.

Ontogeny of the protophloem fibers and secondary xylem fibers within the stem of Coleus. II. An electron microscope study

1975 ◽  
Vol 53 (16) ◽  
pp. 1672-1697 ◽  
Author(s):  
Thompson Demetrio Pizzolato ◽  
Charles Heimsch
Keyword(s):  
Secondary Wall ◽  
Secondary Xylem ◽  
Ultrastructural Changes ◽  
Wood Fibers ◽  
Wall Formation ◽  
Phloem Fibers ◽  
Membrane Bound ◽  
Secondary Wall Formation ◽  
Pass Through ◽  
Xylem Fibers

Ultrastructural changes within the protophloem fibers and secondary xylem fibers accompany their ontogeny in the Colens stem. The plasmalemma of both fibers portrays a gently undulating pattern against the wall before secondary wall formation. Commonly a narrow, hyaline region separates the primary wall and the plasmalemma. Fibrillar material arising from the plasmalemma is condensed in the wall. With the onset of secondary wall formation, undulation of the plasmalemma increases. Many microtubules traverse the membrane and are modified into extracytoplasmic microtubules. Vesicles produced by the dictyosomes and endoplasmic reticulum (ER) pass through or fuse with the plasmalemma. These processes abate after the initiation of the secondary wall. Cisternal, vesicular, and tubular forms of ER, the latter a rare form in wood fibers, fluctuate in amount during ontogeny. Mitochondria increase in number by fission and change in size and cristae volume. Microbodies are common in the youngest phloem fibers but are absent from the xylem initials. Microbodies arising as swellings of ER cisternae are numerous after secondary wall formation is underway in both fibers. Microfilaments are rare in wood fibers but are common in young phloem fibers. Spherosomes, which originate from ER cisternae, disappear during the initiation of the secondary wall. Phloem fiber plastids increase in number by either constriction or concentralization until shortly after the start of secondary wall formation. The plastids of the xylem fibers differ from those of the phloem fibers since the organelles contain phytoferritin and large starch grains initially, divide only by constriction, and do not form membrane-bound bodies.

scholarly journals Arabidopsis XTH4 and XTH9 contribute to wood cell expansion and secondary wall formation

2019 ◽  
Author(s):  
Sunita Kushwah ◽  
Alicja Banasiak ◽  
Nobuyuki Nishikubo ◽  
Marta Derba-Maceluch ◽  
Mateusz Majda ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Expansion ◽  
Cell Walls ◽  
Secondary Wall ◽  
Secondary Xylem ◽  
Cell Wall Integrity ◽  
Wall Thickening ◽  
Xylem Cell ◽  
Secondary Wall Thickening ◽  
Secondary Wall Formation

ABSTRACTIn dicotyledons, xyloglucan is the major hemicellulose of primary walls affecting the load-bearing framework with participation of XTH enzymes. We used loss- and gain-of function approaches to study functions of abundant cambial region expressed XTH4 and XTH9 in secondary growth. In secondarily thickened hypocotyls, these enzymes had positive effects on vessel element expansion and fiber intrusive growth. In addition, they stimulated secondary wall thickening, but reduced secondary xylem production. Cell wall analyses of inflorescence stems revealed changes in lignin, cellulose, and matrix sugar composition, indicating overall increase in secondary versus primary walls in the mutants, indicative of higher xylem production compared to wild type (since secondary walls were thinner). Intriguingly, the number of secondary cell wall layers was increased in xth9 and reduced in xth4, whereas the double mutant xth4x9 displayed intermediate number of layers. These changes correlated with certain Raman signals from the walls, indicating changes in lignin and cellulose. Secondary walls were affected also in the interfascicular fibers where neither XTH4 nor XTH9 were expressed, indicating that these effects were indirect. Transcripts involved in secondary wall biosynthesis and in cell wall integrity sensing, including THE1 and WAK2, were highly induced in the mutants, indicating that deficiency in XTH4 and XTH9 triggers cell wall integrity signaling, which, we propose, stimulates the xylem cell production and modulates secondary wall thickening. Prominent effects of XTH4 and XTH9 on secondary xylem support the hypothesis that altered xyloglucan can affect wood properties both directly and via cell wall integrity sensing.SIGNIFICANCE STATEMENTXyloglucan is a ubiquitous component of primary cell walls in all land plants but has not been so far reported in secondary walls. It is metabolized in muro by cell wall-residing enzymes - xyloglucan endotransglycosylases/hydrolases (XTHs), which are reportedly abundant in vascular tissues, but their role in these tissues is unclear. Here we report that two vascular expressed enzymes in Arabidopsis, XTH4 and XTH9 contribute to the secondary xylem cell radial expansion and intrusive elongation in secondary vascular tissues.Unexpectedly, deficiency in their activities highly affect chemistry and ultrastructure of secondary cell walls by non-cell autonomous mechanisms, including transcriptional induction of secondary wall-related biosynthetic genes and cell wall integrity sensors. These results link xyloglucan metabolism with cell wall integrity pathways, shedding new light on previous reports about prominent effects of xyloglucan metabolism on secondary walls.One sentence summaryXTH4 and XTH9 positively regulate xylem cell expansion and fiber intrusive tip growth, and their deficiency alters secondary wall formation via cell wall integrity sensing mechanisms.

Molecular mechanism of AtGA3OX1 and AtGA3OX2 genes affecting secondary wall thickening in stems in Arabidopsis

2013 ◽  
Vol 35 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Zeng-Guang WANG ◽  
Guo-Hua CHAI ◽  
Zhi-Yao WANG ◽  
Xian-Feng TANG ◽  
Chang-Jiang SUN ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Secondary Wall ◽  
Wall Thickening ◽  
Secondary Wall Thickening

scholarly journals Desenvolvimento e mudanças celulares na estrutura dos raios xilemáticos de Rollinia emarginata Schlecht. (Annonaceae)

1988 ◽  
Vol 10 (10) ◽  
pp. 131
Author(s):  
Paulo Cesar Botosso
Keyword(s):  
Secondary Xylem ◽  
Intrusive Growth ◽  
Outermost Layer ◽  
Cellular Changes ◽  
Fusiform Initials ◽  
Cellular Transformations ◽  
Ray Initials

Through microscopical observations in serial tangential sctions from cambium to pith the development and the most significant cellular changes in the structure of rays of Rollinia emarginata Schlecht. (Annonaceae) were observed. The ray characteristics of the outermost layer of secondary xylem are described and the major changes in the ray structure in different stages of secondary develooment are considered. The cellular changes observed are extremely variable, occurring isolated or in complex combinations. The most significant cellular changes observed during ray development are the following: origin of ray initials from fusiform initials or from cambial ray initials; changes resulting from the intrusive growth of fusiform initials through a group of ray initials and the loss of ray initials from the cambium. From these cellular transformations the most important changes in the origin of secondary rays, increase in height and width and reduction in the height of multisseriate rays are considered.

The secondary phloem of Austrobaileya scandens

1970 ◽  
Vol 48 (2) ◽  
pp. 341-359 ◽  
Author(s):  
Lalit M. Srivastava
Keyword(s):  
Tannic Acid ◽  
Cross Sections ◽  
Significant Proportion ◽  
Sieve Tube ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Sieve Cells ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Definition Of

The origin of sieve elements and parenchyma cells in the secondary phloem of Austrobaileya was studied by use of serial cross sections stained with tannic acid – ferric chloride and lacmoid. In three important respects, Austrobaileya phloem recalls gymnospermous features: it has sieve cells rather than sieve-tube members; a significant proportion of sieve elements and companion cells arise independently of each other; and sieve areas occur between sieve elements and companion cells ontogenetically unrelated to each other. The angiospermous feature includes origin of most sieve elements and parenchyma, including companion cells, after divisions in phloic initials. In these instances companion cells show a closer ontogenetic relationship to sieve elements than do other parenchyma cells. The combination of gymnospermous and angiospermous features makes phloem of Austrobaileya unique when compared to that of all those species that have been investigated in detail. It is further suggested that the term albuminous cells is inappropriate and should be replaced by companion cells but that the ontogenetic relationship implicit in the definition of companion cells is too restrictive and should be abandoned.

SECONDARY GROWTH IN THE STEM OF SOME SPECIES OF ALTERNANTHERA AND ACHYRANTHES ASPERA (AMARANTHACEAE)

IAWA Journal ◽  
2000 ◽  
Vol 21 (4) ◽  
pp. 417-424 ◽  
Author(s):  
Kishore S. Rajput ◽  
K.S. Rao
Keyword(s):  
Secondary Growth ◽  
Sieve Tube ◽  
Axial Parenchyma ◽  
Achyranthes Aspera ◽  
Companion Cells ◽  
Cambial Variant ◽  
Mother Cells

Secondary growth in Achyranthes aspera, Alternanthera polygamous, A. pungens, A. sessilis, and A. triandra was achieved by the development of a cambial variant resulting in successive rings of xylem and phloem. Each new cambium was developed at a distance about two to three cells external to the phloem produced by the previous cambium. The development of phloem was not synchronous in the species studied. Phloem development started either simultaneously with xylem or after the formation of a few xylem derivatives. In Achyranthes, xylem production started first followed by the development of phloem. Phloem mother cells differentiated into sieve tube elements, companion cells and axial parenchyma. Xylem was storied and exclusively composed of axial elements. Radial elements were absent in all the xylem rings of the stem. Vessels were angular and mostly solitary, but radial and tangential multiples were also observed occasionally. Xylem fibres were nonseptate and nucleated. Development of phloem and the rayless nature of the xylem is discussed.

Regeneration of vascular tissue through redifferentiation of interxylary phloem after complete girdling in Aquilaria sinensis

IAWA Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Bei Luo ◽  
Arata Yoshinaga ◽  
Tatsuya Awano ◽  
Keiji Takabe ◽  
Takao Itoh
Keyword(s):  
Time Course ◽  
Potential Role ◽  
Vascular Tissue ◽  
Secondary Xylem ◽  
Vascular Cambium ◽  
Aquilaria Sinensis ◽  
Phloem Fibers ◽  
Interxylary Phloem ◽  
Time Course Study

Abstract We studied the time-course of stem response for six months following complete girdling in branches of Aquilaria sinensis to determine the potential role of interxylary phloem (IP) in this response. It was found that the vascular cambium, as well as its derivative secondary xylem and phloem, regenerated fully through redifferentiation of IP. We confirmed that vascular cambium regenerated within one month after girdling based on observation of new vessels, IP, and secondary phloem fibers. The time-course study showed that IPs made connections with each other, merged, and became larger through the proliferation of IPs parenchyma cells and the cleaving of secondary xylem in a narrow zone 400 to 1000 μm deep inside the girdled edge. This led to the formation of a complete circular sheath of vascular cambium, followed by the regeneration of vascular tissue. It is worth noting that the secondary xylem is regenerated always following the formation of a thick belt of wound xylem.

Defoliation constrains xylem and phloem functionality

2019 ◽  
Vol 39 (7) ◽  
pp. 1099-1108 ◽  
Author(s):  
Rachel M Hillabrand ◽  
Uwe G Hacke ◽  
Victor J Lieffers
Keyword(s):  
Vascular Function ◽  
Tree Mortality ◽  
Vascular Tissue ◽  
Vascular Dysfunction ◽  
Sieve Tube ◽  
Carbon Limitation ◽  
Transport Efficiency ◽  
Increased Risk ◽  
Phloem Fibers ◽  
The Stability

AbstractInsect defoliation contributes to tree mortality under drought conditions. Defoliation-induced alterations to the vascular transport structure may increase tree vulnerability to drought; however, this has been rarely studied. To evaluate the response of tree vascular function following defoliation, 2-year-old balsam poplar were manually defoliated, and both physiological and anatomical measurements were made after allowing for re-foliation. Hydraulic conductivity measurements showed that defoliated trees had both increased vulnerability to embolism and decreased water transport efficiency, likely due to misshapen xylem vessels. Anatomical measurements revealed novel insights into defoliation-induced alterations to the phloem. Phloem sieve tube diameter was reduced in the stems of defoliated trees, suggesting reduced transport capability. In addition, phloem fibers were absent, or reduced in number, in stems, shoot tips and petioles of new leaves, potentially reducing the stability of the vascular tissue. Results from this study suggest that the defoliation leads to trees with increased risk for vascular dysfunction and drought-induced mortality through alterations in the vascular structure, and highlights a route through which carbon limitation can influence hydraulic dysfunction.

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