Rayless Secondary Xylem of Halophytum

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.

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Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet

IAWA Journal ◽

10.1163/22941932-90000938 ◽

1985 ◽

Vol 6 (3) ◽

pp. 187-199 ◽

Cited By ~ 18

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.

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An Important Part of Wood Formation Mechanism – Secondary Xylem Development (I). Coniferous Trees. Si Ci Yin, xiv + 674 pp., illus., 2013. Science Press Beijing. ISBN 978-703-037664-0. Price USD 85.00 (hard cover).

IAWA Journal ◽

10.1163/22941932-00000061 ◽

2014 ◽

Vol 35 (2) ◽

pp. 213

Author(s):

Pieter Baas

Keyword(s):

Formation Mechanism ◽

Secondary Xylem ◽

Wood Formation ◽

Coniferous Trees ◽

Xylem Development ◽

Hard Cover

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

Lebanese Science Journal ◽

10.22453/lsj-021.2.119-128 ◽

2020 ◽

Vol 21 (2) ◽

pp. 119-128

Author(s):

Asma Rafa ◽

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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.

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

IAWA Journal ◽

10.1163/22941932-bja10075 ◽

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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Conductance in the wood of selected Carboniferous plants

Paleobiology ◽

10.1017/s0094837300013804 ◽

1986 ◽

Vol 12 (3) ◽

pp. 302-310 ◽

Cited By ~ 33

Author(s):

Michael A. Cichan

Keyword(s):

Wood Anatomy ◽

Growth Habit ◽

Secondary Xylem ◽

Middle Part ◽

Specific Conductance ◽

Plant Evolution ◽

Seed Plant ◽

Fossil Plants ◽

Tracheary Elements ◽

Conducting Tissue

Specific conductance was calculated for secondary xylem in seven Carboniferous stem taxa utilizing an equation derived from the Hagen-Poiseuille relation. Arborescent and lianoid representatives of major pteridophytic (Calamitaceae, Lepidodenraceae, Sphenophyllaceae) and gymnospermous (Cordaitaceae, Medullosaceae) groups were examined. In the calamite Arthropitys communis and the seed plant Cordaites (Cordaixylon sp. and Mesoxylon sp.), conductance corresponded approximately to the low end of the range for both extant conifers and angiosperms. A substantially higher conductance was determined for the wood of Arthropitys deltoides, conforming to the high end of the range for conifers and the low-middle part of the range for angiosperms. The highest conductance values were found in Sphenophyllum plurifoliatum, Medullosa noei, and Paralycopodites brevifolius and corresponded to the middle-high portion of the range for vessel-containing angiosperms. This outcome is particularly significant in light of the fact that tracheary elements in the fossils are imperforate. The results indicate that conductance in secondary xylem of some of the most ancient, woody groups was comparable to that in extant plants and that highly effective conducting tissue developed relatively early in plant evolution. Moreover, it is suggested that the general relationship between wood anatomy, growth habit, and ecology demonstrated for living plants can also be extended back in time to include fossil plants.

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

Acta Botanica Brasilica ◽

10.1590/s0102-33062007000400006 ◽

2007 ◽

Vol 21 (4) ◽

pp. 813-822 ◽

Cited By ~ 11

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.

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