Plant Taxonomy with the passage of time deserves holistic approach in the domain of biology.Now, it becomes a synthetic science due to application of other branches of knowledge like Chemistry, Molecular biology etc.This slide is intended to UG & PG students of Botany.

1. 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

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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).

9. 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.

10. 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)

11. 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.

12. 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.

13. 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.

14. 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,

15. 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

16. 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.

17. 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

18. 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.

19. 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.

21. THANK YOU FOR YOUR JOURNEY
Look deep into nature and then you will understand
everything better”-Einstein