Xylem vessel functionality during the maturation of ‘Hayward’ and ‘Zesy002’ kiwifruit

Cochlospermum religiosum (Linn.) Alston. (Bixaceae) otherwise known as Yellow silk cotton tree.Traditionally, the plant is used in the treatment of cough, asthma, jaundice, tuberculosis, inflammation, gonorrhea, fever and dysentery. In the present studymicromorphological investigations and the physicochemical analysis of Cochlospermum religiosumleaves and stem bark were carried out.The macromorphological examination indicated simple, palmately lobed, alternate distichous leaves possessing the prominent parallel venation, acute apices and crenate margin. Similarly, smooth, fibrous, ash coloured bark containing an orange-coloured gummy exudate observed. The microscopy of leaves presented a dorsiventral lamina, long filamentous unicellular uniseriate covering trichomes, anomocytic stomata, annulated lignified xylem vessel, mucilaginous brown matter, starch grains and prisms of calcium oxalate whereas the microscopic examination of the bark indicated lignified cork cells, thick-walled lignified sclereids, bundles of lignified fibres, rounded starch grains, elongated cellulosic medullary rays, tetragonal and rosette crystals of calcium oxalate. Thequalitative analysis of inorganic elementsexhibited the presence of aluminium, sodium, calcium, chlorides and ironin leaves and the bark ofCochlospermum religiosum.The present investigation on pharmacognostic characters and analytical standards of Cochlospermum religiosumwill provide a diagnostic tool in the authentication and the assessment of its quality.

Download Full-text

Mutations in the tomato gibberellin receptors suppress xylem proliferation and reduce water loss under water-deficit conditions

Journal of Experimental Botany ◽

10.1093/jxb/eraa137 ◽

2020 ◽

Vol 71 (12) ◽

pp. 3603-3612 ◽

Cited By ~ 2

Author(s):

Natanella Illouz-Eliaz ◽

Idan Nissan ◽

Ido Nir ◽

Uria Ramon ◽

Hagai Shohat ◽

...

Keyword(s):

Water Deficit ◽

Water Status ◽

Stomatal Closure ◽

Normal Growth ◽

Hydraulic Conductance ◽

Xylem Vessel ◽

Leaf Water Content ◽

Whole Plant ◽

Drought Conditions ◽

Better Than

Abstract Low gibberellin (GA) activity in tomato (Solanum lycopersicum) inhibits leaf expansion and reduces stomatal conductance. This leads to lower transpiration and improved water status under transient drought conditions. Tomato has three GIBBERELLIN-INSENSITIVE DWARF1 (GID1) GA receptors with overlapping activities and high redundancy. We tested whether mutation in a single GID1 reduces transpiration without affecting growth and productivity. CRISPR-Cas9 gid1 mutants were able to maintain higher leaf water content under water-deficit conditions. Moreover, while gid1a exhibited normal growth, it showed reduced whole-plant transpiration and better recovery from dehydration. Mutation in GID1a inhibited xylem vessel proliferation, which led to lower hydraulic conductance. In stronger GA mutants, we also found reduced xylem vessel expansion. These results suggest that low GA activity affects transpiration by multiple mechanisms: it reduces leaf area, promotes stomatal closure, and reduces xylem proliferation and expansion, and as a result, xylem hydraulic conductance. We further examined if gid1a performs better than the control M82 in the field. Under these conditions, the high redundancy of GID1s was lost and gid1a plants were semi-dwarf, but their productivity was not affected. Although gid1a did not perform better under drought conditions in the field, it exhibited a higher harvest index.

Download Full-text

Sap flow, xylem anatomy and photosynthetic variables of three Persea species in response to laurel wilt

Tree Physiology ◽

10.1093/treephys/tpaa137 ◽

2020 ◽

Author(s):

Raiza Castillo-Argaez ◽

Aime Vazquez ◽

Joshua L Konkol ◽

Ana I Vargas ◽

Randy C Ploetz ◽

...

Keyword(s):

Tree Species ◽

Sap Flow ◽

Xylem Sap ◽

Forest Tree ◽

Persea Americana ◽

Xylem Vessel ◽

Xylem Anatomy ◽

Laurel Wilt ◽

Raffaelea Lauricola ◽

Leaf Chlorophyll

Abstract Laurel wilt, a lethal vascular wilt disease caused by the fungus Raffaelea lauricola, affects several tree species in the Lauraceae, including three Persea species. The susceptibility to laurel wilt of two forest tree species native to the southern United States, Persea borbonia and Persea palustris, and avocado, Persea americana cv Waldin, was examined and related to tree physiology and xylem anatomy. Net CO2 assimilation (A), stomatal conductance (gs), leaf chlorophyll index (LCI), leaf chlorophyll fluorescence (Fv/Fm), xylem sap flow, theoretical stem hydraulic conductivity (Kh) and xylem vessel anatomy were assessed in trees of each species that were inoculated with R. lauricola and in control trees. Laurel wilt caused a reduction in A, gs, LCI, Fv/Fm, and blockage of xylem vessels by tyloses formation that negatively impacted Kh, and sap flow in all Persea species. However, disease susceptibility as indicated by canopy wilting and sapwood discoloration was less pronounced in P. americana cv Waldin than in the two forest species. Xylem vessel diameter was significantly smaller in P. borbonia and P. palustris than in P. americana cv Waldin. Differences in laurel wilt susceptibility among species appears to be influenced by physiological and anatomical tree responses.

Download Full-text

Xylem vessel‐diameter–shoot‐length scaling: ecological significance of porosity types and other traits

Ecological Monographs ◽

10.1002/ecm.1410 ◽

2020 ◽

Vol 90 (3) ◽

Cited By ~ 4

Author(s):

Mark Olson ◽

Julieta A. Rosell ◽

Cecilia Martínez‐Pérez ◽

Calixto León‐Gómez ◽

Alex Fajardo ◽

...

Keyword(s):

Vessel Diameter ◽

Shoot Length ◽

Xylem Vessel ◽

Ecological Significance ◽

Length Scaling

Download Full-text

Structure and Biomechanics during Xylem Vessel Transdifferentiation in Arabidopsis thaliana

Plants ◽

10.3390/plants9121715 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1715

Author(s):

Eleftheria Roumeli ◽

Leah Ginsberg ◽

Robin McDonald ◽

Giada Spigolon ◽

Rodinde Hendrickx ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Cell Walls ◽

Turgor Pressure ◽

Plant Cells ◽

Building Blocks ◽

Xylem Vessel ◽

Primary Cell Wall ◽

Individual Plant ◽

Vessel Elements

Individual plant cells are the building blocks for all plantae and artificially constructed plant biomaterials, like biocomposites. Secondary cell walls (SCWs) are a key component for mediating mechanical strength and stiffness in both living vascular plants and biocomposite materials. In this paper, we study the structure and biomechanics of cultured plant cells during the cellular developmental stages associated with SCW formation. We use a model culture system that induces transdifferentiation of Arabidopsis thaliana cells to xylem vessel elements, upon treatment with dexamethasone (DEX). We group the transdifferentiation process into three distinct stages, based on morphological observations of the cell walls. The first stage includes cells with only a primary cell wall (PCW), the second covers cells that have formed a SCW, and the third stage includes cells with a ruptured tonoplast and partially or fully degraded PCW. We adopt a multi-scale approach to study the mechanical properties of cells in these three stages. We perform large-scale indentations with a micro-compression system in three different osmotic conditions. Atomic force microscopy (AFM) nanoscale indentations in water allow us to isolate the cell wall response. We propose a spring-based model to deconvolve the competing stiffness contributions from turgor pressure, PCW, SCW and cytoplasm in the stiffness of differentiating cells. Prior to triggering differentiation, cells in hypotonic pressure conditions are significantly stiffer than cells in isotonic or hypertonic conditions, highlighting the dominant role of turgor pressure. Plasmolyzed cells with a SCW reach similar levels of stiffness as cells with maximum turgor pressure. The stiffness of the PCW in all of these conditions is lower than the stiffness of the fully-formed SCW. Our results provide the first experimental characterization of the mechanics of SCW formation at single cell level.

Download Full-text