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Uploaded byNistarini College, Purulia (W.B) India
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Taxonomy a synthetic science

The document discusses the evolution of taxonomy, highlighting the distinction between classical and modern taxonomy, which incorporates various scientific fields such as cytology, phytochemistry, palynology, and molecular biology for greater accuracy. Key contributions from cytology include chromosome studies aiding taxonomic classification, while phytochemistry involves biochemical characteristics to address classification challenges. The integration of molecular data and techniques is emphasized as essential for confirming taxonomic relationships, ultimately advocating for taxonomy as a synthetic science that evolves from its historical roots to modern applications.

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TAXONOMY-A SYNTHETIC SCIENCE By N.Sannigrahi,Associate Professor, Deptt. Of Botany, Nistarini College, Purulia (W.B) Synthetic Science -the field involves the input of the different domains of wide branches of knowledge of the scientific field. The classical or alpha taxonomy mainly depends on the gross morphological data but the modern or omega taxonomy acknowledges the data of the different field includes anatomy, cytology, photochemistry, immunology, palynolgy, molecular biology as well as Bioinformatics to make the field more accurate with mathematical interpretation using the databases. Let us explore the following fields ad how they have enriched this domain of knowledge keeping with the trend of modern science. -----Cytology -----Phytochemistry -----Palynology ------Molecular data
Cytology-an aid to modern taxonomy • Cytology-the branch of science mainly deals with the structure of plant & animal cells and its components in the different spheres of knowledge in applicability. Cytotaxonomy studies includes-a. Chromosome number,b.hromosome size, c. chromosome morphology, d. chromosome behavior at meiosis e. Banding patterns and their application in solving taxonomic problems.
Cell-the treasure of knowledge • Cell along with the new world of membranes, organelles, microtubules and components of nucleus, ribosome, mitochondria, plastids and the genetic information has revolutionized the field of thinking of human. Chromosomes with wide diversity and biparental inheritance along with the uncountable irregularities-both in the number and the morphology offer unique opportunity to explore the diversity of biological world and the phylogeny. The chromosome number relationship with taxonomic groups can be broadly classified into the following categories-Constant number, Euploidy, Polyploidy-Dibasic polyploidy, anueuploidy- trisomics(2n+1),tetrasomics(2n+2), monosomics(2n-1), Nullisomics(2n-2) and B-Chromosomes. In Malvaceae, the somatic number range from 15,20, 25,--40 so on. Cardamine hirsuta of 2n=16 & Cardamine flexuosa of 2n=32 is a polyploidy pairs.
Chromosome morphology • Karyotype-a group of species resembling each other in the number, size, and form of chromosomes and the figures in idiogram or karyograms(P-petite)/q. The karyotype can be characterized by relative length of chromosomes, position of centromere and the presence of satellites. chromosomes either symmetrical- metacentric(V) or sub-metacentric(L) & Asymmetrical- Acrocentric(J) or Telocentric(I).generally, asymmetrical karyotype are common in plants and symmetrical are some of the generalized plants .The absolute size of the chromosomes in karyotype is fairly constant with species specificity(Davis & Heywood,1963).Advanced genera of Aconitum & Delphinium(Ranunculaceae), the flowers have largest number of J-shaped chromosomes.
Chromosome behavior & banding pattern • Synopsis during meiotic prophase & frequency of chiasma considered to address taxonomic issues. Translocations, inverssion-paracentric or pericentric, deletions and duplications of chromosomes may alter the meiotic behavior. Structural differences in the chromosomes of two species are a consequence of morphological modifications of chromosomes. Giemsa & flurochrome dyes uses to study the banding pattern used to distinguish morphologically between chromosomes with enhanced efficiency.
Some examples of cytology in taxonomic issues • 1. In Ranunculaceae, all the genera with n=7,8,9 having long & short chromosomes have been placed under Anemoneae & Helloeboreae. • 2.Several taxonomists treated genera Physaria & Lesquerella of Brassicaceae as a single genus but cytological data strengthen different genera. • 3.Agave, Yucca,& Funkia show that they hve chromosome no x=30 with 25s & 5L.The genus Polianthes shows same result. So, Polianthes should include under Agaveles with other three genera. • Chromosomal characteristics alone are not always a reliable taxonomic criteria, nor they are considered as phylogenetic marker.
PHYTOCHEMISTRY IN TAXONOMY Chemotaxonomy or Biochemical systematics mainly deals with the chemical characters of plants like primary constituents-proteins, nucleic acid, polysaccharides, secondary constituents- polyphenolic (terpenes, flavonoids, coumarins), pheolic(Benzoic, caffeic and nicotinic acid) or other substances like ellagitanins,iridoid compounds to address the different issues & challenges in taxonomy. These characters may help in plant classification and additional knowledge of phylogeny. Alston & turner(1963),Gibbs(1974), Heywood(1973) are pioneers in this field.
SOME EXAMPLES OF UNIQUE SIGNIFICANCE • Protein-It provides an inner view into the cell’s genome, as the amino acids sequences in proteins are encoded by the nucleotide sequences of cell’s DNA as per central dogma of life(DNA → mRNA →Protein).Electrophoresis,NMR spectroscopy& Chromatography techniques enable to find out the relationship.1.The phylogenetic affinities of Triticinae by the electrophoresis (Johnson& Hall,1965).2. Interspecific variations of eight species of Cassia on the basis of seed protein & mitochondrial DNA RFLP by gel electrophoresis (Mondal et al,2000).
Homology of Amino acids sequence • The degree of the amino acid sequence is presumably proportional to the degree of genetic relationship(Sivrajan,1984).On the basis of the sequence homology, the phylogeny of various taxa like Malvaceae, Rananculaceae,(Martin & Dowd, 1984),Magnoliaceae & Polygonaceae, Myrtales & Solanaceae(Martin et al.,1984) has been found that contribute in phylogenetic study. Comparative studies of enzymes may yield data about the differences in primary structure , which can be traced to evolutionary adaptation.
Flavonoids-a phylogenic inference • Flavonoids-phytochemical constituent being a phenol glycosides consisting of two benzene rings linked together through a heterocyclic pyrane ring, of different classes- Flavones(Levtolin), Isoflavones(Orobol), flavones (Kaempferol), Anthocyanidines(Cyanidin) etc.According to Swain(1975), during the course of flavonoids increased in their structural complexity from primitive glycoflavone(Chara) to proanthocyanindins(Pteridophytes & Gymnosperms).Analysis of flavonoids of the leaf of Liliaceae, Juncaceae, Cyperaceae & Poaceae by Williams(!976) suggests that all these families have been derived from Liliaceous ancestors. • Flavonoids have been used in the estimation of generic affinities in Ulmaceae(Giannasi,1978)and of species relationships of Chenopodium(Crawford & Evans,1978)
Alkaloids-an aid to phylogeny • Heterocyclic ring compounds having N2 containing , a by-products of plant metabolism from amino acids and their derivatives. True alkaloids,protoalkaloid & pseudoalkloids distributed throughout the plant tissues distributed in the different parts. Families like Fabaceae, Ranunculaceae & solanaceae rich in alkaloids including Annonaceae, Fummariacreae,Menospermaceae etc. • According to Jones & Luchsinger(1987), alkaloids are useful in taxonomic studies like Papaver & Argemone of Papaveraceae, Veratrum(Liliaceae) as well as in Lycopodium, Lupinus & Carypphyllales.
Terpenoids Biogenic group of volatile compounds mostly polymerized isoprene residues may be of- Hemiterpenes(Single isoprene, tiglic acid), omonoterpenes(menthol)Sesquiterpenes(Farnesol), diterpenes(Phytol), Triterpenes(squalene) and polyterpenes(Rubber).GLC & mass spectroscopy can help to identify the compounds in plants. Sesquiterpene lactones are common in the family Asteraceae.Geographical races of Pseudotsuga menziesii are distinguished on the basis of terpenoids on their conical oleoresins. The Classification of Eucalyptus has been done on the basis of different terpenoids.Species of Cymbopogon of Poaceae,Ocimum of Lamiaceae, the tribe of Tagitineae of Asteraceae has been done on the basis of terpenoids.
Steroids, Irdoids,oils, fats, waxes Steroids, saturated ring –sterane serve the role of water proof having taxonomic significance The genera of tribe Veratreae of Liliaceae can exhibit this propertities.Iridoids are monoterpenoid cyclopentanoid latones can taxonomic significance.Rosalean & Guttiferalian are connected on the basis of irdoids.Besides these, Linolenic acid, linoleic acid, olei acid, palmitic acid, Calcium oxalate crystals, (Asteraceae) Capric acid(Ulmus)Cuticular waxes(Poaceae)alkane hydrocarbon in Crassulceae, raphides in Rubiaceae are some of the examples can speak the significance of the phytochemical compounds in plant taxonomy.
Palynology in Taxonomy Palynology-study of pollens & spores extensively used in taxonomic & evolutionary studies. Shape & size of pollens, Apertures, Exine sculpturing, Pollen associations, nuclear number of pollen , type, number position and structure of apertures(NPC) are most desirable fields .Pollen morphology has been used in the classification of Acanthaceae(1961), Asclepiadaceae(Radford. Et al,1974), Caryohyllidae(Cronquest,1981), Asteraceae (Slix. 1960),Euphorbiaceae (kohler, 1965),Saxifragraceae(Nair, 1970).Erdtman(1963) use the pollen characters in discussing and solving the taxonomic problems of 105 families.Monosulcate found in primitive dicotyledons while tricolpate in advanced dicotyledons.Stenopalynous in Poaceae where monoporate aperture with smooth exine surface while Eurypalynous having variations in size, aperture , exine stratification as in Euphorbiaceae having taxonomic significance. The different characters like shape-circular, triangular, minute, large, gigantic, pollen association-monad, dyad, tetrad, pollinium,pollen nuclear number-two nucleate, three nucleate,Apertural forms-sulcus, ulcus, colpus, NPC-atreme, monotreme, ditreme, tritreme, tetratreme, hexatreme,
Some examples of family, genus & species level • Catatreme, Anatreme, leptoma, cataleptoma are some of the features taken into account in this regard. • 1.Several families like Poaceae have smooth sulccate pollen; Malvaceae and Asteraceae have spinulose exine; Areaceae & Lemnaceae have stenopalynous,1-2-4 colpate, 3-porate and palynological evidences supported the separation of Faeoniaceae from Ranunculaceae, Fumeriaceae from Papaveracea and Nelumboniceae from Nymphaceae respectively. • 2.The two genera of Phytolaccaceae-Pytolacca & Rivinia has been separated on the basis of Zonocolpate & pantocolpate nature • Salix has long & 3-furrowed pollen while Poplus has spherical pollen without distinct apertures although both of the belongs to Salicaceae • Species of Malva rotundifolia bearing 74-84milimicron while M.sylvestris 105-126 milimicron speaks about species level identification
Molecular data-aid to taxonomy • Classification of plants on the basis of distribution and composition of semantides-DNA,RNA & proteins to establish genetic relationship is the key aspects of molecular taxonomy. Fitch & Margoliash(1967) construct phylogenetic tree on the basis of molecular daa.Taxonomists realized the significance of molecular data and this made them understand that the traditional methods are although important but molecules evidence could be final and confirmatory evidences by using molecular markers. • Molecular Markers: Type-I genes for known traits • II. Type II Used for genes of unknown traits.
Data mining techniques • Allozyme type I marker as the proteins that they encode are associated with some function. Microstaellites & other associated neutral markers of type II markers unless they are associated with the genes of some known function. • Mitochondrial DNA markers-Non-nuclear DNA inherited with a haploid genome • Microsatellites –Repeated several times across various points of DNA. Besides these, Single Nucleotide Polymorphism(SNP), Arbitrary Nuclear DNA markers, Specific Nuclear DNA markers and Expression Sequence Tag(EST) are also used I this regard as source of information in
Techniques used • Technologies like Specific PCR, Size differential PCR, Multiplex PCR,PCR-RFLP, RAPD, AFLP, Quantitative PCR, Microsatellite, DNA bar coding analysis are used extensively in this regard to harvest date for molecular taxonomy. • WHY?-Molecular entities are strictly inheritable, • Molecular characters are unambiguous, • Some regularity in the evolution of molecular traits • Amenable to quantitative treatment, • Homology assessment is easier, • Abundant & less time consuming.
CONCLUSION • Since the time of Theophrastus to until date, the domain of taxonomy has bee extensively flourishing to make it more reliable, scientific with holistic appeal. The classical taxonomy acknowledges the morphological characters are not restricted itself, rather it is the call of the time to construct the predecessor and successor relationship as well as to construct the phylogenetic tree. The different field off sciences has strengthen this field to make it more convenient and almost zero error. Hence, taxonomy rightly deserves the identity of synthetic science.
THANK YOU FOR YOUR JOURNEY Look deep into nature and then you will understand everything better”-Einstein