The Significance of the Leaf Epidermis for the Taxonomy of Cocculus (Menispermaceae)

The confident identification to species rank of fragmentary and sterile plant material is often challenged by the absence of diagnostic characters, which are present in intact specimens, reproductive parts, and plants in habitat. Here, we consider leaf surface micromorphology for the identification of the genus Aloe in the Horn of Africa region. Primary and secondary sculpturing of the leaf epidermis and stomata were characterised from SEM micrographs of 35 taxa representing 31 species of Aloe (Asphodelaceae subfam. Alooideae). Detailed comparison revealed that leaf surface characters are conserved between species and within-species variation is modest. Closely related taxa in the Aloe adigratana—A. camperi—A. sinana species complex could be distinguished using leaf surface micromorphology alone. These characters also guide species delimitation; in the species complex including A. schoelleri and A. steudneri, a narrow circumscription is supported, whereas with A. ankoberensis and A. pulcherrima, a wider circumscription merits consideration. The observed trait combinations are characteristic of plants in xeric environments, with the most notable feature being stomata that are most deeply sunken in species in more arid habitats. Our findings support the use of comparative study of micromorphological leaf surface characters for species identification and taxonomy in the genus Aloe.

Download Full-text

Differential Occurrence of Cuticular Wax and Its Role In Leaf Tissues of Three Edible Aroids of Northeast India

10.21203/rs.3.rs-1065827/v1 ◽

2021 ◽

Author(s):

Facundo Pieniazek ◽

Madhumita Dasgupta ◽

Valeria Messina ◽

Manas Ranjan Sahoo

Keyword(s):

Membrane Integrity ◽

Northeast India ◽

Industrial Applications ◽

Cuticular Wax ◽

Leaf Epidermis ◽

Terrestrial Plants ◽

Protection Factor ◽

Static Contact ◽

Leaf Tissues ◽

Edible Aroids

Abstract Localization of cuticular wax (CW) on the leaf epidermis and its interaction with physiological mechanisms of three edible aroids, Alocasia, Colocasia, and Xanthosoma, were assessed. Scanning electron microscopy depicted the occurrence of CW in the leaf tissues, which was higher in Colocasia (10.61 mg dm-2) and Xanthosoma (11.36 mg dm-2) than in Alocasia (1.36 mg dm-2). Higher CW in Colocasia and Xanthosoma strengthened leaf epidermis and improved the physiological processes compared to Alocasia. CW acted as a protecting barrier against deleterious solar radiation in terms of sun protection factor (SPF). The glossy appearance of wax crystals in the Alocasia leaf cuticles resulted in higher SPF. The occurrence of CW was directly related to leaf chlorophyll stability, moisture retention ability, and cellular membrane integrity in the leaf tissues. Colocasia exhibited superhydrophobic properties with higher static contact angle (CA) >150o than hydrophobic Xanthosoma, and Alocasia with CA ranged between 99.0o to 128.7o. Colocasia CW highly influenced the qualitative and protective mechanisms of the leaf. Aroids are the cheapest sources of edible CW among the terrestrial plants, which could be used in food, agricultural and industrial applications.

Download Full-text

discordia mutations specifically misorient asymmetric cell divisions during development of the maize leaf epidermis

Development ◽

10.1242/dev.126.20.4623 ◽

1999 ◽

Vol 126 (20) ◽

pp. 4623-4633 ◽

Cited By ~ 2

Author(s):

K. Gallagher ◽

L.G. Smith

Keyword(s):

Cell Division ◽

Preprophase Band ◽

Cytochalasin D ◽

Leaf Epidermis ◽

Asymmetric Cell Divisions ◽

Maize Leaf ◽

Cell Divisions ◽

Cytoskeletal Structure ◽

Dividing Cells ◽

Preprophase Bands

In plant cells, cytokinesis depends on a cytoskeletal structure called a phragmoplast, which directs the formation of a new cell wall between daughter nuclei after mitosis. The orientation of cell division depends on guidance of the phragmoplast during cytokinesis to a cortical site marked throughout prophase by another cytoskeletal structure called a preprophase band. Asymmetrically dividing cells become polarized and form asymmetric preprophase bands prior to mitosis; phragmoplasts are subsequently guided to these asymmetric cortical sites to form daughter cells of different shapes and/or sizes. Here we describe two new recessive mutations, discordia1 (dcd1) and discordia2 (dcd2), which disrupt the spatial regulation of cytokinesis during asymmetric cell divisions. Both mutations disrupt four classes of asymmetric cell divisions during the development of the maize leaf epidermis, without affecting the symmetric divisions through which most epidermal cells arise. The effects of dcd mutations on asymmetric cell division can be mimicked by cytochalasin D treatment, and divisions affected by dcd1 are hypersensitive to the effects of cytochalasin D. Analysis of actin and microtubule organization in these mutants showed no effect of either mutation on cell polarity, or on formation and localization of preprophase bands and spindles. In mutant cells, phragmoplasts in asymmetrically dividing cells are structurally normal and are initiated in the correct location, but often fail to move to the position formerly occupied by the preprophase band. We propose that dcd mutations disrupt an actin-dependent process necessary for the guidance of phragmoplasts during cytokinesis in asymmetrically dividing cells.

Download Full-text