Morphological and Anatomical Features of Leaf and Stem of

Dioscorea Nipponica Makino

Dilfuza

Berdibaeva

, Gulnoza

Atabaeva

, Gulom

Jumaboyev

, Mavluda Amanova

and Gulbahor Sultanova

Tashkent State Agrarian University, 100140, University str. 2, Tashkent, Uzbekistan

Keywords: Dioscorea Anatomy, Stem Structure, Leaf Morphology.

Abstract: In this article Dioscorea nipponica Makino. information on the anatomical structure of the leaf and stem of

the species, the location, structure and functions of each tissue. The results of this study support the taxonomy

of D. nipponica species based on anatomical structure. This study showed that the leaves and stems of

Dioscorea nipponica have characteristics similar to those of Eudicot. Our observations showed that the leaf

surface of Dioscorea nipponica is covered with solitary trichomes. The structure of the vascular bundle is

represented by a definitive V-shaped arrangement of metaxylem vessels, tracheids and phloem units. Raphid

crystals are present in the leaf mesophyll tissue. It was also found that the stem shape is undulating,

parenchyma cells are saturated with granular substance, conducting tissues are arranged in 2 rows, conducting

vessels are paired

1 INTRODUCTION

Dioscorea nipponica Makino. - is a perennial

herbaceous liana of the Dioscoreae family

(Dioscoreaceae R.Br.), reaching a length of 4-5 m

(Gubanov et al., 1976). The rhizome is horizontal,

shallow from the soil surface, sparsely branched,

brownish-brown (white or yellowish at the break), up

to 1.5 m long and 2 cm in diameter, with traces of

dead stems and numerous thin, rigid cord-like roots

(Anthony and Ibok, 2021). Younger parts of the

rhizome are lighter, yellowish, fleshy, with large

buds; the outer layer of the rhizome is easily separated

as a flaky thin dark-coloured corky layer. Decoction

and tincture of the roots of Dioscorea nipponese folk

medicine recommends atherosclerosis of cerebral

vessels, coronary atherosclerosis, angina pectoris,

hypertension, diabetes mellitus. Already after the first

course of taking dioscorea reduces or disappears

headache, tinnitus, fatigue. Further increases the

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https://orcid.org/0009-0004-8090-0195

removal of cholesterol with bile, improves the work

of the heart, pancreas, liver, kidneys.

2 MATERIALS AND METHODS

Leaves and stems of Dioscorea nipponica were fixed

in 70% ethanol according to a generally recognised

technique and its anatomical structure was studied on

a transverse section of the fixed material

(Trankovsky, 1979).

The anatomical features were studied using

preparations prepared by cutting the transverse

section manually and using a Motic B1 microscope.

The preparations were stained with safranin. Cells

and tissues were measured using a MOB-15

micrometer.

Quantitative measurements of several traits: leaf

diameter, seed coat thickness, seed coat thickness and

360

Berdibaeva, D., Atabaeva, G., Jumaboyev, G., Amanova, M. and Sultanova, G.

Morphological and Anatomical Features of Leaf and Stem of Dioscorea Nipponica Makino.

DOI: 10.5220/0014269600004738

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 4th International Conference on Research of Agricultural and Food Technologies (I-CRAFT 2024), pages 360-365

ISBN: 978-989-758-773-3; ISSN: 3051-7710

endosperm thickness were performed according to

the generally accepted method (Dospekhov, 1985).

Statistical analysis of data was calculated with a

personal computer (MS Excel) using generally

accepted methods. Microphotographs were taken

using a digital camera, and mathematical analysis was

performed using a Motic microscope.

3 RESULTS AND DISCUSSION

Dioscorea has a positive effect on sleep, memory,

vision, depth of breathing, pulse rate. Acts as an anti-

inflammatory agent, reduces blood clotting. Treats

inflammation of the trigeminal nerve. Rhizomes of

Dioscorea contain numerous compounds, but the

main active substances are steroidal saponins (up to 8

%), derivatives of diosgenin, the main of which is

dioscin. Diosgenin can be a starting product for the

synthesis of hormonal drugs - cortisone, progesterone

(Ki-Sun et al., 2020).

There are several stems; they are simple,

glabrous, whorled, about 0.5 cm in diameter. Leaves

are regular, petiolate, broadly ovate with a heart-

shaped base. Flowers with simple corolla-shaped

yellowish-greenish perianth. Fruits are three-nested,

broadly elliptic bolls. Blooms in July-August; seeds

ripen in August-September. In the medical industry,

rhizomes and roots of Dioscorea nipponica are used

to produce the drug polysponin.

Dioscorea nipponica Makino. Far Eastern

species, grows in Primorsky Krai, southern parts of

Khabarovsk Krai and in the south-east of Amur

Oblast, in Primorsky Krai, southern parts of

Khabarovsk Krai and in the south-east of Amur

Oblast, distributed mainly in the north-eastern,

northern, eastern and central regions of China. It also

occurs in mixed forests, on mountain slopes, in

ravines and along roadsides, at altitudes of 1,400-

3,200 m in Guizhou, Sichuan, eastern Xizang and

Yunnan provinces. Most often found in secondary

plant communities occurring on clear-cutting and fire

sites. Listed in the Red Data Book of Russia

(Harkevich, 2012).

Dioscorea nipponiana was introduced from

Russia to Uzbekistan in 1996 by Y.M. Murdahaev;

today it grows only in the Tashkent Botanical Garden

(Murdakhayev, 1990). We tudied morphological and

anatomical structures of the leaf in the conditions of

the Botanical Garden (Fig. 1.).

Figure 1: General view of Dioscorea nipponica Makino.: a

- general view,b - flowers, c – rhizome.

The leaves are three and seven-lobed. Leaves are

evenly arranged on the stem in an orderly fashion

(Fig.2).

Figure 2: Morphological structure of the leaf of Dioscorea

nipponica Makino.

Leaves are broadly heart-shaped in outline, with

strongly projecting auricles; their veining is arcuate,

most often 9 primary veins reach the leaf tip. The

marginal veins ensure the strength of these "wind"

leaves, which, obviously, is also served by

anastomoses between primary veins, formed by veins

of the 2nd order and creating a common reticulate-

nerve veining. The leaf tip is strongly elongated into

a drop-shaped tip. Such droplet spicules hanging

downward from the leaf allow water runoff from its

surface and water secreted by hydatodes. However,

they exhibit an interesting peculiarity of internal

structure. The whole length of the leaf tip is crossed

here inside by a complex glandular system of cavities

(pockets) with a slit-like exit to the surface of the drop

spicule. The glandular epithelium of the cavities

secretes mucus in them, in which nitrogen-fixing

bacteria settle. It was also found that the nitrogen

content in the drop spicules is higher than in the leaf

lamina.

Morphological and Anatomical Features of Leaf and Stem of Dioscorea Nipponica Makino

361

Features of leaf epidermis that revealed

similarities between wild-type and micropropagated

plants included amphistome state, presence of mucus,

glandular unicellular trichomes with multicellular

heads, polygonal cells with smooth walls, and type

and shape of stomata. Minor variations included a

thick cuticular wall with closed stomata in wild-type

plants compared with thin-walled open stomata in in

vitro plants. The opening of the stomata resulted in an

increase in the average size of the stomata (7.68-0.38)

μm and (6.14-0.46) μm on the adaxial side (Aina et

al., 2011).

Examined under optical microscope, scanning

electron microscope (SEM) and transmission electron

microscope (TEM) for stem, leaf, petiole, tuber, root

and flower of Dioscorea hispida Dennst. provided

detailed information on the anatomical features that

defined this species. The anatomical study showed

that the leaves of Dioscorea hispida had similar

features to eudicot plants, but the stem, tuber and

flower resembled unicotyledonous plants. The leaf

surface of Dioscorea hispida was covered with rough,

bristly and spiny trichomes or hairy surface (Bu,

2015).

Structure of the leaf lamina of Dioscorea

nipponica (1-drawing).

Figure 3: General view of a transverse section of a

Dioscorea nipponica Makino. leaf: PP-Conducting bundle,

HE- upper epidermis, NE-lower epidermis, SCL-

sclerenchyma, PL-palisade, CR- raphid crystals.

The epidermis is a layer of cells that protects

against harmful environmental influences and

excessive water evaporation. The upper (adaxial) and

lower (abaxial) epidermis have a single layer of cells,

each covered by a cuticle. Often on top of the

epidermis, the leaf is covered with a protective layer

of waxy origin (cuticle). The stomata are restricted to

the lower surface only (hypostomal). In the epidermis

of Dioscorea nipponica leaves, anamocytic and

anisocytic stomata, as well as single pilosebaceous

trichomes with cuticular striated cell wall were found

on the adaxial and abaxial epidermis. Also, raphide

crystals are present in the epidermis.

The palisade (above, densely packed cells) and

spongy (below, loosely packed cells) portions of the

mesophyll, located between the upper and lower

epidermal layers, are shown. The mesophyll, or

parenchyma, is the inner chlorophyll-bearing tissue

that performs the main function, photosynthesis.

Network of veins formed by conducting bundles

(conducting tissue) consisting of vessels and sieve-

like tubes for the movement of water, dissolved salts,

sugars and mechanical elements.

Stomata are special complexes of cells located

mainly on the lower surface of leaves; they are used

for evaporation of excess water (transpiration) and

gas exchange. Epidermа is the outer layer of a

multilayered cell structure that covers the leaf from

all sides; the boundary area between the leaf and the

environment. The epidermis performs several

important functions: it protects the leaf from

excessive evaporation, regulates gas exchange with

the environment, excretes metabolic substances and,

in some cases, absorbs water. Most leaves have a

dorsoventral anatomy: the upper and lower surfaces

of the leaf have different structures and perform

different functions.

The epidermis is usually transparent (there are no

or few chloroplasts in its structure) and is covered on

the outside by a protective layer of waxy origin

(cuticle), which prevents evaporation. The cuticle on

the lower part of the leaf is generally thinner than on

the upper part, and thicker in biotopes with arid

climates compared to those where there is no

moisture deficit. The epidermal tissue consists of the

following cell types: epidermal (or motor) cells,

defense cells, accessory cells, and trichomes.

Epidermal cells are the most numerous, largest

(11.2±0.3, 15.4±0.4) and least adapted (9.1±0.2,

11.1±0.4). The epidermis is covered with pores called

stomata, which are part of a whole complex

consisting of a pore surrounded on all sides by

chloroplast-containing guard cells and two to four

side cells lacking chloroplast.

This complex regulates evaporation and gas

exchange of the leaf with the environment. As a rule,

the number of stomata on the lower part of the leaf.

Most of the leaf interior between the upper and

lower layers of the epidermis is parenchyma (the

main tissue), or mesophyll. Normally, the mesophyll

is formed by chlorophyll-synthesizing cells, so the

synonymous name chlororenchyma is also used. The

product of photosynthesis is called photosynthate.

Leaves are usually colored green due to

chlorophyll, a photosynthetic pigment found in

chloroplasts, the green plastids. Plants lacking or

lacking chlorophyll cannot photosynthesize. The veins

consist of xylem, the tissue used to conduct water and

I-CRAFT 2024 - 4th International Conference on Research of Agricultural and Food Technologies

362

Table 1: Quantitative parameters of Dioscorea nipponica leaf mesophyll.

№ Si

ns Indicators, microns

Length of the upper epidermis

11,2±0,3

Width of upper epidermis

9,1±0,2

Length of lower epidermis

15,4±0,4

Width of lower epidermis

11,1±0,4

5 Palisade length 13,2±0,4

6 Palisade width 10,1±0,2

7 Sclerenchyma length 12,2±0,4

8 Sclerenchyma width 11,3±0,2

9 Parenchyma length 14,5±0,4

10 Parenchyma width 13,3±0,3

Figure 4: Transverse section of Dioscorea nipponica stem: A - general view, B - peel, C - pith: C - cortex, S - sclerenchyma,

PP - conductive bundles, SG - granular matter.

dissolved minerals, and phloem, the tissue used to

conduct organic matter synthesized by the leaves.

Usually the xylem lies on top of the phloem. Together

they form the main tissue called the leaf core. The

lamina has 3-4 protruding veins running from the base

to the apex. The cuticle of the lamina is soptically

thickened.

The leaf has a layered epidermis, the soptic wall

on the abaxial cells is convoluted and the adaxial cells

have a straight wall. Stomata with irregular

distribution and anomocytic type are found on the

abaxial surface. Palisade tissue was clearly

distinguished, elongated, compactly arranged and

oriented vertically, with a transverse section on the

adaxial side (13.2±0.4, 10.1±0.2), and spongy tissue

was arranged either loosely or compactly with

irregularly sized cells.

Dioscorea nipponica on transverse section is

round to wavy in shape, internal cells and tissues are

densely arranged (Fig. 4).

The stem is finely cellular, covered with cortex on

the outside. The structure of the cortex (containing

Morphological and Anatomical Features of Leaf and Stem of Dioscorea Nipponica Makino

363

chloroplast) consists of one row of epidermis with

cuticle and 4-5 rows of parenchyma cells under it.

The parenchyma cells are followed by a ring of 5-6

rows of thin-walled sclerenchyma cells. After the

sclerenchyma cells there are large and small

conducting bundles. The bundles have pairs of large

vessels.

The central core consists of parenchyma cells,

which increase in size as you approach the centre.

Among the parenchyma cells, granular filled cells can

be observed.

Epidermal cells are 13 µm high and 10 µm wide.

The table below summarises the size of all organoids

of the stem (Table 2).

Table 2: Anatomical parameters of stem Dioscorea nipponica.

№

mbols Indicators, µm

Epidermal height

13,3±0,3

Epidermal width

10,1±0,2

Sclerenchyma length

11,2±0,4

Sclerenchyma width

9,3±0,2

Parenchyma length

12,5±0,4

Parenchyma width

11,3±0,3

Height of large conductive bundles

18,8±0,5

Width of large conductive bundles

15,4±0,4

Length of smaller conductive bundles

9,4±0,3

Width of smaller conductive bundles

8,1±0,2

The anatomical structure of the stem of Dioscorea

nipponica is little studied than leaves, tubers, roots,

rhizomes (Martin et al., 1963), (Cunyu et al., 2022),

(Vı´tor et al., 2016), (Berdibaeva and Atabaeva,

2023).

We anatomically characterised the aerial stems of

the genus Dioscorea and evaluated the possibility of

using these anatomical characteristics to better

understand the taxonomy, systematics and diversity

of component species in the non-tropics. Air stem

fragments from 23 species were collected for

anatomical analysis using conventional

cytohistological techniques (Berdibaeva, 2021).

4 CONCLUSIONS

Dioscorea has two layers of vascular bundles, with

the outer layer containing sclerenchyma and the

medulla having sclereids, in contrast the parenchyma

had a sclerenchyma layer with vascular bundles. The

sclerenchyma layer in the stem may increase

mechanical strength.

In conclusion, we would like to report that the study

of the anatomical structure of the cross-section of the

stem Dioscorea nipponica is established, has a wavy

shape, parenchyma cells have filled with granular

substances, two-row arrangement of conductive

bundles, the presence of paired vessels.

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