|ANATOMICAL FINGER PRINT AND BIOCONSTITUENTS AS SYSTEMATICAL TOOLS IN SOME DICOT. SEEDS
1-Seed surface scan and seed morphology.
Shahine*,A.H., Wanas*,A.L., Faten*,H.M. Ismaeil, Abd El-Migid**,A.A. and Abd El-All*,M. M. M.
* Dep. of Agric. Botany, Faculty of Agric., Moshtohor, Zagazig University.
** Horticulture Research Institute (Flora)
The present thesis is devoted to investigate the exomorphological and surface scan – of some seeds - attribute by using light and scanning electron microscope, as well as, micromorphological characters and chemical composition of seeds of three different species, each include two varieties or cultivars, representing three genera and three families as follows:-
(From Malvaceae, cotton seed cvs. Giza 86 and Giza 66, Solanaceae, tomato seed vars. Pyriforme and grandifolium and Brassicaceae, rape seed cv. Pactal and var. Tower). The seeds under study even cultivars or varieties were obtained from The Seed Bank Of Flora and Phytotoxonomy Research Department (CAIM), Horticultural Research Institiute (HRI), Agricultural Research Center (ARC). The aim of the present work was to clearity the importance and the significance of the seed morphological attributes and chemical composition to faciliate the process of differentiation and identification of these cultivars and varieties, as well as, using these attributes and chemical composition as critera in taxonomic aspects. The different seed exomorphological, surface scan, anatomical attributes and chemical composition of the studied taxa are presented in forms of cumulative tables and plates, as well as, microphotographic pictures and hand drawings of the cross section of seeds in order to facilitate observation of variations, similarities, correlations and differences among the taxa.
The main results could be summarized as follows:-
1-According to seed exomorphology, the variation in the seed shape, color and size were of great importance and could be considered as good diagnostic features that make the differentiation and separation among the studied cultivars and varieties easier and more effective.
2-The combination of both seed surface patterns and micromorphological characteristics could be useful in delimitation of the studied taxa.
3-The examination of seed surface scan, by using SEM showed different or namentation of the seed surface which could be considered major significant diagnostic attributes to facilitate the separation of taxonomic unites.
4-From the anatomical point of view, there are anatomical characters that could be useful in delimitation of the studied taxa.
5-The cuticle thickness is considered as diagnostic features that could be depended on identification of some taxa rather than classificatory purposes.
6-A ccording to anticlinal and periclinal walls, it was noticed that this feature is of a great importance and could be considered as a good diagnostic feature which make the differentiation and identification of the studied material more clear and effective.
Plant taxonomy has drawn great attention of many scientists dealing with this scope of study. Different trends dealing with the basis of plant taxonomy, especially, those related to plant families.
That is why we find many researches dealing with the basis of taxonomy, especially, those based on the following characteristics:-
-The exomorphological, surface scan characters (using light and scanning electron microscope) and micromorphological attributes of seeds. These features are significantly employed as acriterion for taxonomic treatments Stace (1980). Also these features are of great importance and could be considered as good diagnostic features that make the differentiation and separation between the cultivars more effective and easier as wellAbo-Baker (2004).
The main object of the present investigation is to throw light on the exomorphological, surface scan characters (Using light and scanning electron microscope) and micromorphological attributes of seeds of three species, included two even cultivars or varieties for each specie (representing 3 families and 3 genera).
Hence, the present work intended to apply morphological attributes to facilitate identification and separaction of the studied taxa, as well as, studying their use as criteria in taxonomic aspects.
1. Plant materials:
In this work, seeds of three different species of three families [i.e., Malvaceae, Solanaceae and Cruciferae (Brassicaceae)] were taken as plant materials in this study. For each species; seeds of two economical varieties or cultivars were secured from Seed Bank Of The CAIM-Herbarium of Flora and Phytotaxonomy Department, Horticulture Research Institute (HIR), (ARC), Agricultural Museum, Dokki, Giza. The studied taxa belong to three genera namely: Gossypium, Lycopersicon and Brassica according to Hutchinson’s classification (1973).
Table (1): The species under investigation showing the different families and genera according to Hutchinson’s (1973).
Table (1): The different species taken as plant material in the present study.
Varieties or Cultivars
barbadense L. cv. Giza 86
barbadense L. cv. Giza 66
esculentum L. var. Pyriforme
esculentum L. var. Grandifolium
napus L. cv. Pactol
napus L. var. Tower
2. Methods :
2.1. Seed surface scan, macro and micro-morphology:
2.1.1. Gross macromorphological “Phenology” aspects:
The general morphological description of each species was complied from the current text books of plant taxonomy such as Tindall (1993) and Boulos (1999).
2.1.2. Seed exomorphology and surface scan aspects:
Seed dimensions were measured by binocular stereo-microscope using ocular micrometer. The general exomorphological characteristics features of the seeds were examined by the same microscope.
Scanning Electron Microscope (SEM), at 25 Kv. using different magnifications. The (SEM) micrographs were taken after the mounting of the completely mature dry seeds with (SPI) supplies; conducting carbon paint, on copper stubs coated with a thin layer of gold palladium in Edwards Sputter Coater; S 150 B, and examined in different positions using different magnifications by JEOL-JSM-T100 Scanning Electron Microscope at the Faculty of Science, Zagazig University.
The SEM-micrographs were used to facilitate the description of seed exomorphology. The magnification power was expressed by (X) for each SEM-photograph. In this connection it must be mentioned that the magnification power of the SEM were changed from 35 X to 1500 X, among the taxa investigated to clarify the finest details, as well as the characters of more interest.
In case of large-sized seeds which were out of SEM field (cotton seed). The stereo microscope photographs were taken in the National research center, Dokki, Giza.
Glossary to descriptive terms for the seed surface scan after Murley (1951), as cited by Stearn (1983)”
.Reticulate: With a raised network of narrow and sharply angled lines frequently presenting ageometric appearance, each area or depression outlined by reticulum being an interscope.
Favulariate : With the surface finally ribbed, the ribs are separated by zigzag furrows.
Rugose: Wrinkled, the irregular elevation making up the wrinkles and running mostly in one direction.
Undulate: Appear as sea waves.
2.1.3. Seed micromorphology:
Comparative microscopial examination of seeds of all genera and cultivars (cotton, tomato and rape) took place.
The dry seeds were soaked in water and then killed and fixed in F.A.A. (5ml formalin, 5ml glacial acetic acid and 90 ml ethyl alchohol 70%), washed in 50% ethyl alchohol, dehydrated in series of ethyl alcohols 70, 80, 90, 95 and 100%, infiltrated in xylene, embedded in paraffin wax of a melting point of 60-63°C, sectioned 20 microns in thickness (Sass, 1951).
The sections were stained with the double stain method (safranin and fast green), cleared in xylene and mounted in canada-balsam (Johanson, 1940).
Drawings were made at bench level by aid of leitz camera Lucida. The magnification was given by beck-stage micrometer scaled 0.01 to 0.1 mm.
RESULTS AND DISCUSSION
- Seed exomorphology (Table, 2 & Plate,1):
Shape of seeds (Table 2 & Plate VII):
Obovate: Gossypium barbadense L. cv. Giza 86 and Gossypium barbadense L. cv. Giza 66.
Oval with tapering end: Lycopersicon esculentum L. var. pyriforme and Lycopersicon esculentum L. var. grandifolium.
Slightly globose: Brassica napus L. cv. Pactol.
Oblong shiny and minute coarse: Brassica napus L. var. Tower.
Seed colour (Table 2):
The colour of seeds of the studied cultivars and varieties was either dark brown to black as in Gossypium barbadense cultivars, straw yellow in Lycopersicon esculentum L. var. pyriforme, pale yellow in Lycopersicon esculentum L. var. grandifolium, dark brown in Brassica napus L. cv. Pactol or light brown in Brassica napus L. var. Tower.
Of the main workers are Chang and Heckard (1972) who depended on seed colour in some delimitations. On the other hand, the seed colour is of rather limited taxonomic value (Hausain et al. 1990). Furthermore, the justification of this rejection is supported by the fact that the seed colour is an attribute which depends largely on the metabolic activities within the plant on one hand and the effect of the enviromental conditions on the other hand (Karakish, 1993). This character has no effective consideration among the other good ones for its possible fluctuation with the same taxon at different duration (Hussein, 1995).
Size of the seed Table (2):
Small-sized seeds: Less than 2mm long as in Brassica napus L. var. Tower.
Large-sized seeds: i.e., more than 4 mm long as Gossypium barbadense cultivars.
Median-sized seeds: 2-4mm long as in Lycopersicon esculentum varieties.
Heinisch (1955) recorded some characters and measurerments of the seeds of some species of a trifolium genus. Peinado et al. (1971) provided a key to 13 of trifolium species based on size and weight of their seeds. Stebbins, (1974) emphasized that the precise adjustment of seed size is often highly adaptive and the reproductive success is dependent upon strong buffering and canalization of the processes involved in seed development. Thompson (1981) stated that such attributes are subjected to ecological and physiological variations. Mourad (1988) and Karakish (1993) stated that the seed size is unreliable for both identification or differentiation.