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Genetics And Plant Breeding

Plant Breeding for competitive exam

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Genetics And Plant Breeding

Plant Breeding

· From the radical a seminal root originates, produces two lateral roots referred to as “Seminal root system”.
· Stem – Culm.
· Ligule – Membranous hairy structure present at the function of leaf sheath and leaf blade.
· Auricles – Ear like appendages on either side of the ligule.
· Panicle – Spikelets may be pedicellate (or) sessile.
· Spike – Spikelets are sessile only.
· Perianth – represented by 2 lodicules which are hygroscopic, helping for pollination.
· Sub family Graminae:
Pooideae – basal floret perfect a while upper florets imperfect – Spikelets are laterally compressed.
Panicoideae – basal floret imperfect upper florets perfect – dorsally compressed.
· Sugarcane, Sorghum tribe – Andropogonae
Maize – Maydeae Panicoideae
Wheat – Hordeae
Ragi tribe – Chlorideae Pooideae

1. Paddy:
· Some spikelet glumes may be elongated nearly half to the length of the spikelet. Such spikelet is described as “Winged Spikelet”.
· The mid vein of lemma is prolonged into “awn”.
· The tip of lemma and palea are together projected and known is as “apiculus”.
· Fruit is described as “Caryopsis”.
· Paddy is “Protandrous”.

2. Sorghum:
· Sorghum verticillium – Higher content of HCN (Dhurrin).
· Fibrous roots along with stilt roots.
· Auricle absent.
· Lodicules 2, Fleshy, truncate, ciliate.
· Sessile floret is grain forming.
· Peduncle may be erect” (or) bending downwards – “goose necked”.
· Sorghum cerneum – Tellajonna; S. roxburghi – Konda jonna.

3. Maize :

Zea mays varieties evertq – pop corn
· Inflorescence monoecious and open panicle.
· Style – a single long thread like structure known as “Silk”, divided into two (or) bifid
stigma, Protein – Zein,
4. Wheat : Inflorescence – Spike of spikelet. 2n = 6 X = 42.
· Peduncle is zig zag rachis.
· In fruit longitudinal groove on the ventral side is known as “Crease”. On either side of it
the elevated regions are known as “Cheeks” and on the stigmatic side small hairs are
present known as “brush”.

5. Bajra:

Pennisetum americanum
P. purpureum – Napier grass.
· Because of the short lateral branches, minute pedicels, the inflorescence may give a false
appearance as a spike (Spiciform).
· On the tip of the anther lobes minute, unicellular hairs are present in the form of pencil
cone. So it is described as “Penicellate anthers”. Which helps in anthers flush from
bisexual flowers.
· Styles 2 but fused to one known as connate style. It is helped in emergence of stigmas
from the bisexual floret.
· This crop is highly “Protogynous”, cross pollinated

6. Korra:

Fox tail millet; Italian millet; Setaria italica.
· The bristles are considered as reduced (or) modified “Spikelets”.

7. Arika:

Kodo millet; Paspalum scrobiculatum.
· Winged rachis is present.
· Immature plants, grains with husk are hharmful to cattle with more HCN content.
· Dehusked grains is known as “Chicco”.
· Cleistogamous” pollination (S.F in unopened flower condition).
· Echinochloa colonum – “Oodalu” – Barnyard millet.
· Cleistogamy is seen in Arika, Bengalgram.

8. Ragi:

Eleucine coracana
· Leaves give whorleed appearance.
· Inflorescence “terminal digilate whorl of spike”.
· One (or) two finger occur little below to the terminal whorl known as the “Thumb”.
· Paleas bikeeled (or) double boat shaped.
· Fruit – Utricle.

9. Pulses:

· Papillionaceous corolla is responsible for the zygomorphic nature.
· Aestivation – The arrangement of sepals and petals in relation to the adjacent ones in bud
condition.
Tribe Example
Hydecereae Arachis – leaves, Paripinnate.
Eienistlea Sunhemp – leaves simple.
Vicieae Pea, Bengalgram – Imparipinnate leaves
Phaseoleae Redgram – Pinnate

10. Bengal gram:

Chick pea – Cicer arietinum (or) Gram
· Surface of the plant shows small glandular hairs containing “Oxalic and malic acids”.
· Persistant calyx (Sepals) is present, Jointed peduncle seen.
· Fruit legume (or) pod with presistant calyx and styles described as “beaked”.
· Cleistogamy is seen.
· Hilum – Place of attachment of seeds to pericarp.

11. Cowpea:

Vigna catgung (or) Indian pea. Known as vebetable meat.
· Fruit has longest pod among all the pulses.
· More number of seeds per pod of all the pulse crops.

12. Glycine max:

Soybean
· Below the stigma small hairs are present. Described as “bearded”.
· Used as minor pulpse and mostly as a source of oil edible.

13. Pea:

Pisum sativum
· Fruit – a much swollen pod.

14. Redgram:

Cajanus cajan
· Long peduncles and flowers are seen as clusters at the tip of the penducle.
· Among all the pulse crops flowering continuous for long period in the variety Prabhat,
Puragati.

15. Horse gram:

Dolichos biflorus (or) Macrotylomia uniflorus
· Inflorescence; facile – group of 2-3 pedicellate flowers (or) sessile flowers in the axil of
bract.
· Sepals companulate (cup shape).
· Use horse gram without splitting.
· Fruit “Sickle shaped pod”.

16. Garden bean:

Dolichos lablab var. Typicus – seeds are parallel to the pericarp.
· Field bean: Dolichos lablab var. Lignosus – seed are right angle to the pericarp.

Oil seed crops:-

· Fatty (or) fixed – do not volatile (or) evaporate when exposed to atmosphere.
· Essential oil – Volatile (or) evaporate when exposed to atomosphere.
· All oils are in liquid form consisting of linoleic and oleic acids.
· Tuberous roots – “Dhalia”.
· In ray florets and disc florets calyx generally as “Pappus”.
· Syngenesious – the another lobes are united while the filaments are free. In compositae –
fruit – cypsela (with persistant pappus).
· Safflower oil is best for heart patients because of high “Linoleic acid” content.

17. Ground nut:-

Origin – Brazil
· Sepals united forming a long calyx tube represented as “Pseudopedicel”.
· Androecium “Monadelphous”. Androecium present at the rim of the calyx tube,
antherlobes dimorphic (Morphologically dissimilar).
· This crop show longest flowering period.
· From the proteins of the cotyledons a synthetic fibre is synthesized used in textile
industry known as “ardil”.

17. Gingelly:

F: Pedaliaceae
· “Bilabiate” corolla (two posterial petals upper lip; 3 anterial petals lower lip)
· Androecium “Didynamous” (2 stamens with short filament and 2 with long filament)

18. Coconut:-

Long – Cocos nucifera var. typical
Dwarf – cocas nusifera var. nana

19. Castor:

· Waxy coating – bloom
· Male flowers at the base – arranged in “irregular cymes”.
· Female flowers at the top – arranged in “recemose”.
· Branched stamens are present.
· The tip of stigmas covered with prominent bright red hairs, hence stigmas are
“Papillose”.
· Fruit: A warty schizocarpic Regma (each bit coccus).
· Spongy out growth of outer seed coat – “Carunile”. Carunile (or) Eloisomes.
· Thick endosperm which is the source of oil – capions.
· The endosperm encloses thin “Leaf like cotyledons”.

Fibre crops:-

1. Lingnified fibres – Schlerenchymatous cells. Flax fibre = Linseed fibre. eg: sun hemp, Deccan hemp, manila hemp.

2. Cellulose fibre – Cotton, flax.
· Bast fibre – Sunhemp, flase, manila hemp.
· Wood fibre – obtained from the xylem. Eg: Bamboo

1. Cotton:

· Single bundle completely enriches the ovary and style of the gynecioum and forming
“Staminal colums”.
· Aborted avotes which are known as “Motes”.

2. Hibiscus cannabinus:

Bhimilipatnam jute, Deccan hemp, Mestafibre
H.sabdriffa – Roselle
· Each sepal is showing a prominentelivated midrib at the centre of which a prominent
involucaral gland is present.

3. Corchorus capsularis:

C. olitorius – Bengal jute F: Teliaceae
· Fibres are extracted by Retting process. It is mricrobial process by clostridium.
· C. Olilorius – Fossajute.
· Also known as ‘Goldenfibre’ – JRF – 2012

Sugarcane:

· Small longitudinal slits present in the epidermis are known as “Corky cracks” (or) “ivory
marks”.
· The bud is protected by two lateral outgrowths known as “Flangens”.
· In the bud groove region, small horizontal cracks are known as “Knife cuts”.
· At the ligule region the inner surface of the leaf sheath is known as “throat” outer surface
is known as “Collar”.
· Inflorescence – Arrow (or) open panicle.

Tobacco:-

· Many minute ovules as swollen axile – placenta.
Chilli : – Capsium annum
· Inflorescence – extraxillary formed by the terminal bud
· Alkaloid – Capsacin, Red colour: Capsanthin
· Variety – Jwala.
· In sugar beet economic part – modified tap root.
· In Sago (Metroxylon sago) economic part is the central pith region of the trunk.
· In saffron – style and stigmas are the economic plant parts.
· Alkaloid in arecanut – “Arekalin”.
· Maize cobs, the nodes and internodes are very much condersed and the basal portion is
called “Shank”.
· Safflower dye – “Carthamin”.
· Tobacco is the golden leaf of India.
· In Safflower, calyx is absent. It is cross pollinated crop. Often cross pollinated.
· Chilli is very rich in Vitamin “C”.
· In cool temperature “Linoleic acid” content increases in sunflower.
· Six stamenal cereal – Rice
· Seed cotton is called – Kapas.
· The walls of pericarp in cotton is collectively called ‘Vue’.
· A bast fibre yielding crop belonging to the family – Malvaceae
· Bark oil – Cinnamomum xylanicum.
· Barkspice – “Chakka” in Telugu.
· Pinnately trifoliate leaf – Redgram.
· A berry with leathery peicarp – Capsicum.
· Tubular florets – Disc florets; Ray florets – ligulate.
· Epicalyx – Cotton
· In bajra “lodicules are absent”.
· Ciliate lodicules – Sorghum, Wheat.
· Sessile stigma – coconut.
· Bajra composite – Balaji, Maize synthetic – Amber leaf blight resistant cotton –
Varalakshmi.
· Induced mutant in Groundnut – MC – 4, resistant to tikka leat spot – Ab – 45.
· Turmeric variety released through clonal selection – Kasthuri Kesari.
· Rice variety resistant to stem borer – Ratna: TKM – 1.
Gall midge – Siam 29.
· In the segregating population when the progenies fall beyond the reach of the parents it is
known as “Transgressive segregation”.
· Inbreeding depression is not observed in self pollinated crops. Mutation breeding is
commonly used in self pollinated cropsinbreeding depression is common in
“Crosspollinated” crops.
· Natural selection plays an important rule in “Bulkmethod”.
· Double stranded RNA – Reovirus.
· Double stranded DNA is – Cauliflower mosaic virus.
· Primary cell walls of adjacent cells are connected by “Middle lamella” which is made up
of pectin.
· Cell wall is not present in animal cells.
· Primary cell wall appears in the form of strains under electron microscope these are
called “Micro fibrils”.
· Lignin is generally a component of secondary cell wall.
· Pinacocytosis is ingestion of liquid food material.
· Phagocytosis is ingestion of solid substances.
· Plant cells are connected to one another by “Plasmodesmata”.
· Cisternae – long flattened channels. It is the common form Vesicles – oval membrane.
· Smooth ER is also known as “Sarcoplasmic reticulum”.
· In plant cells and in lower invertebrates golgicomplex is referred ad “Dictyosomes”.
· Golgi complex helps to form the cell wall in plants.
· Primary lysosomes – Storage granules, secondary lysosomes – digestive vacuoles.
· Digestion of the own cellular organells – Autolysis.
· Power house of cell is Mitochondria.
· Ribosomes are classified based on their “Sedementation co-efficient” expressed as
“Svedberg units”.
· Peroxysomes are involved in photorespiration and in the metabolism of H2O2.
· Glyoxysomes are abundant in germinating seeds.
· Spherosomes are involved in lipid synthesis.
· Micro filaments help in the cleavage of cytoplasm during cell division and form the
contractile machinery of the cell.
· In animals polynucleate cells are known as ”Syncytial” and in plants they are known as
“Coenocytic”.
· Nucleolus helps for biogenesis of ribosomes.
· Synthesis of DNA itself is called “Autocatalytic function”.
· DNA directs the synthesis of chemical molecule other than itself “Hetero catalytic
function”.

1. Cistron – The portion of DNA specifying a single polypeptide chain is termed as cistron.
2. Muton – As unit of mutation.
3. Recon – Smallest unit of DNA; capable of recombination.

· Synthesis of mRNA from DNA as a complementary strand is “Transcription”.
· tRNA bring one amino acid each for a triplet codon as anticodes and thus is known as “translation” (Protein synthesis).
· “Trillium” is having the longest chromosome.
· Chromosomes without centromere are acentric.
· The short segment of the nucleolar organizer chrososome, distal to the secondary
constriction is called “Satellite”.
· The two distal ends of the chromosome maintains “polarity” are known as “Telomere”.
· The stained body of the chromosomes shows differential staining capacity at different
parts is known as “Heteropicnosis”.
1. Euchromation – Light stained, genetically active.
2. Hetero chromatin – Dark stained, genetically in active.
· When the chromosomes are arranged according to size, shape and structure, it is called
“Karyotype”.
· When these are represented by a diagram then such diagrams are called “Idiograms”.
· Endomitosis is resulting due to “Polytene chromosomes” present in salivary glands of
“Drosophila”.
· Outer enlargement of polytene chromosomes are called as “Puffs”.
· Lampbrush chromosomes. Loops are present.
· Isochromosomes – They are metacentric chromosomes having similar genetic
constitution in both arms.
· Interphase is the first stage of mitosis.

1. G1 phase : growth;

S phase – doubling of nuclear components.

G2 phase: doubling of cytoplasmic components, chromatin is reduced.

Karyokinesis – division of nucleus;

cytokinesis – division of cytoplasm.

· Longest phase of mitosis – Prophase.
· Most of the Karyotypic studies are done from metaphase to anaphase.
· The sister chromatids begin to move towards opposite side – “Segregation”.
· The ‘Phragmoplast’ with deposition of pectin forms the middle lamella separating the daughter nuclei.
· In meiosis prophase I is the longest of all the stages.
· In Zygotene, chromosomes begin to pair and the pairing is known as “Synapsis”.
· The point of interchange of the genetic material is called “Chiasma” it takes place in pachytene.
· Anaphase – I is the root cause for heriditary variance because of segregation.
· Locus – location of a gene which is fixed on chromosome.
· One, two (or) more alternative forms of a gene are called “alleles”.
· Monohybrid – law of segregation (or) law of purity of gametes.
· Dihybrid – law of independent assortment.
· Phenotypic classes and gamets – 2n; minimum population – 4n, genotypic classes -3n.
· Paramutations are exceptions to the law of purity of gametes
· Linkage is an exception to mendal’s law of independent assortment
· A gene influencing more than one character – Pleiotropic gene and such phenomena is called “Pleiotropism”.
· Genes which cause a deviation from the normal development lethal gene – ratio – 2:1.
· Pseudoalleles – Structurally different, but functionally similar. The effect produced by
them is known as “cis trans effect”. Alleles occupy same loci.
· Multiple alleles – alleles occur in several alternative forms for particular character.
· Over dominance – When the heterozygotes have more extreme phenotype than either of
the corresponding “homozygotes”.
· Co-dominance – Lack of dominant and recessive relationship and the ratio is (1:2:1).
· Incomplete dominance – blending inheritance – 1:2:1. (in mono hybrids).


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