Biometry and verification of papermaking potential of secondary xylem fibers of two Theobroma species

2020 ◽  
Author(s):  
Alisson Rodrigo Souza Reis ◽  
Cassiele Fonseca da Cruz
Keyword(s):  
Secondary Xylem ◽  
Xylem Fibers

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 Development of successive cambia and structure of the secondary xylem in some members of the family Amaranthaceae

2019 ◽  
Vol 6 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Ravindra A. Shelke ◽  
Dhara G Ramoliya ◽  
Amit D Gondaliya ◽  
Kishore S. Rajput
Keyword(s):  
Secondary Wall ◽  
Secondary Xylem ◽  
Secondary Phloem ◽  
Successive Cambia ◽  
The Family ◽  
Parenchyma Cells ◽  
Plant Habit ◽  
Cambial Cells ◽  
Gomphrena Celosioides ◽  
Xylem Fibers

Young stems of Aerva javanica (Burm.f.) Juss. ex Schult., A. lanata (L.) Juss. ex Schult, A. monsonia Mart., A. sanguinolenta (L.) Blume, Alternanthera bettzickiana (Regel) G. Nicholson, A. philoxeroides (Mart.) Griseb., Gomphrena celosioides Mart., G. globosa L. and Telanthera ficoidea (L.) Moq., showed the renewal of small sectors of cambium by replacing with new segments. Therefore, the secondary phloem formed by earlier cambial segments form isolated islands of phloem enclosed within conjunctive tissues became embedded in the secondary xylem. As the stem grows older, complete ring of cambium is renewed; sometimes an anastomosing network of successive cambia may be seen due to the renewal of larger segments of the cambium. Renewal of the cambium takes place by repeated periclinal division in the parenchyma cells positioned outside to the phloem formed by the previous cambium. Functionally the cambium is bidirectional and exclusively composed of fusiform cambial cells. Differentiation of conducting elements of the secondary xylem and phloem remains restricted to the certain cambial cells while rest of the segments exclusively produce conjunctive cells. Accumulation of starch along with the presence of nuclei in the xylem fibers even after deposition of the secondary wall is consistent in all the species and it seems to be associated with the absence of rays in the secondary xylem and phloem of nine species from four genera. The significance of successive cambia, rayless xylem and nucleated xylem fibers were correlated with plant habit.

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 Functional Characterisation of the Poplar Atypical Aspartic Protease Gene PtAP66 in Wood Secondary Cell Wall Deposition

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1002
Author(s):  
Shenquan Cao ◽  
Cong Wang ◽  
Huanhuan Ji ◽  
Mengjie Guo ◽  
Jiyao Cheng ◽  
...  
Keyword(s):  
Cell Wall ◽  
Secondary Cell Wall ◽  
Fluorescent Protein ◽  
Secondary Xylem ◽  
Populus Trichocarpa ◽  
Wood Formation ◽  
Protease Gene ◽  
Cellulose Content ◽  
Transcription Analysis ◽  
Functional Characterisation

Secondary cell wall (SCW) deposition is an important process during wood formation. Although aspartic proteases (APs) have been reported to have regulatory roles in herbaceous plants, the involvement of atypical APs in SCW deposition in trees has not been reported. In this study, we characterised the Populus trichocarpa atypical AP gene PtAP66, which is involved in wood SCW deposition. Transcriptome data from the AspWood resource showed that in the secondary xylem of P. trichocarpa, PtAP66 transcripts increased from the vascular cambium to the xylem cell expansion region and maintained high levels in the SCW formation region. Fluorescent signals from transgenic Arabidopsis plant roots and transiently transformed P. trichocarpa leaf protoplasts strongly suggested that the PtAP66-fused fluorescent protein (PtAP66-GFP or PtAP66-YFP) localised in the plasma membrane. Compared with the wild-type plants, the Cas9/gRNA-induced PtAP66 mutants exhibited reduced SCW thickness of secondary xylem fibres, as suggested by the scanning electron microscopy (SEM) data. In addition, wood composition assays revealed that the cellulose content in the mutants decreased by 4.90–5.57%. Transcription analysis further showed that a loss of PtAP66 downregulated the expression of several SCW synthesis-related genes, including cellulose and hemicellulose synthesis enzyme-encoding genes. Altogether, these findings indicate that atypical PtAP66 plays an important role in SCW deposition during wood formation.

Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet

IAWA Journal ◽  
1985 ◽  
Vol 6 (3) ◽  
pp. 187-199 ◽  
Author(s):  
Hans Georg Richter
Keyword(s):  
Diagnostic Tool ◽  
Secondary Xylem ◽  
Secondary Phloem ◽  
Structural Profile ◽  
Quantitative Characters ◽  
Important Diagnostic Tool ◽  
Species Groups ◽  
Bark Anatomy

Qualitative features of the secondary xylem of Licaria present a rather uniform structural profile. Constant differences in primarily quantitative characters lead to the formation of speeies groups wh ich loosely correspond to infrageneric sections based on floral and vegetative morphology. This subdivision is strongly corroborated by the highly variable secondary phloem structurc revealing considerable diversity in type and distribution of sc1erenchymatic tissues. Inorganic inclusions in the secondary xylem, crystals and silica, constitute an important diagnostic tool for differentiating certain species and species groups, but are hardly of importance in the bark.

Rayless Secondary Xylem of Halophytum

1978 ◽  
Vol 105 (1) ◽  
pp. 39 ◽  
Author(s):  
Arthur C. Gibson
Keyword(s):  
Secondary Xylem

Resilience aspects of woody plant species at the passage of fire: case of Quercus coccifera in Tlemcen Mountains (Algeria)

2020 ◽  
Vol 21 (2) ◽  
pp. 119-128
Author(s):  
Asma Rafa ◽  
◽  
Mohamed Berrichi ◽  
Ahmed Haddad ◽  
◽  
...  
Keyword(s):  
Heat Conduction ◽  
Porous Structure ◽  
Root System ◽  
Cross Sections ◽  
Woody Plant ◽  
Secondary Xylem ◽  
Woody Species ◽  
Average Diameter ◽  
Quercus Coccifera ◽  
Pyrolysis Gases

In this study, on the aspects of the resilience of woody species to the passage of fire, we wanted to test the alveolar specificity represented by the size of the pores of the secondary xylem of the root system in Quercus coccifera L., Pore size assessment is based on measuring 100 pores in cross sections, from the roots of 10 shrubs. The aim of this study is to explain how the roots can maintain their vitality after passing a fire and thus guarantee regeneration. In addition to the vigor of the root system of this species, the release of pyrolysis gases and the propagation of heat by conduction are provided by the porosity of the material. The results show that the pores are qualified as “fine” in the initial wood with an average diameter of 83.35 µm. In final wood, they are "very thin" with 42.30 µm in diameter. The absence of oxygen and the less porous structure delay the combustion cycle of the root system, the roots distant from the surface are thus protected from proliferation by heat conduction and thus guarantee regeneration.

Structure of the secondary xylem and development of a cambial variant in Serjania mexicana (Sapindaceae)

IAWA Journal ◽  
2021 ◽  
pp. 1-11
Author(s):  
Kishore S. Rajput ◽  
Amit D. Gondaliya ◽  
Roger Moya
Keyword(s):  
Secondary Xylem ◽  
Secondary Growth ◽  
Stem Anatomy ◽  
The Family ◽  
Ray Cells ◽  
Cambial Variant ◽  
Proportional Increase ◽  
Plant Families ◽  
Ray Parenchyma Cells ◽  
Cambial Variants

Abstract The lianas in the family Sapindaceae are known for their unique secondary growth which differs from climbing species in other plant families in terms of their cambial variants. The present study deals with the stem anatomy of self-supporting and lianescent habit, development of phloem wedges, the ontogeny of cambial variants and structure of the secondary xylem in the stems of Serjania mexicana (L.) Willd. Thick stems (15–20 mm) were characterized by the presence of distinct phloem wedges and tangentially wide neo-formed cambial cylinders. As the stem diameter increases, there is a proportional increase in the number of phloem wedges and neo-formed vascular cylinders. The parenchymatous (pericyclic) cells external to phloem wedges that are located on the inner margin of the pericyclic fibres undergo dedifferentiation, become meristematic and form small segments of cambial cylinders. These cambia extend tangentially into wide and large segments of neoformations. Structurally, the secondary xylem and phloem of the neo-formed vascular cylinders remain similar to the derivatives produced by the regular vascular cambium. The secondary xylem is composed of vessels (wide and narrow), fibres, axial and ray parenchyma cells. The occurrence of perforated ray cells is a common feature in both regular and variant xylem.

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