Plant Breeding & Genetics Important Table (1)

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Plant Breeding & Genetics Study Material

Subject:- Plant Breeding & Genetics

Plant Breeding & Genetics Important Point

1.Difference between translocation and crossing over

Translocation	Crossing over
It involves in non-homologous chromosome.	It involves in non-sister chromatids of homologous chromosomes.
Change the linkage map	Does not change the linkage map.
Breakage and reunion	Chiasma formation.
Pollen and ovule sterility.	No sterility

2.Difference between crossing over and linkage

Crossing over	Linkage
Separation of linked genes	Keeps the genes together
Non-sister chromatids of homologous chromosome involves	Individual chromosomes involves.
Frequency of crossing over never exceed 50%	It can never be more than haploid chromosome number
It increases variability.	It reduces variability
Provides equal frequency of parental and recombinant types in test cross progeny	Provides higher frequency of parental types that recombinant types in test cross progeny.

3.Chemically Induced Male Sterility

CHA	Crop
Ethanol	Rice, sugar beet, wheat.
GA₃	Maize, onion, rice.
NAA	Cucurbits.
Sodium Methyl Arsenate	Rice
MH	Cucurbits, onion, tomato, wheat.

CHA – Male gametocides or Chemical hybridizing agents

MH – Maleic hydrazide

NAA – Naphthaleneacetic acid

4.Genetic Materials

Genetic materials	Definition
Chromatin	It is composed of DNA, protein and RNA.
Histones	Constitute about 80% of the total chromosomal proteins.
Chromosomes	Composed of nucleic acid (DNA or RNA)
Nucleic acid	Contains many nucleotides
Nucleotides	It consist of nucleoside and phosphoric acid.
Nucleoside	Contains sugar + nitrogenous base
Nitrogenous base	Two types Purine (A, G) and pyramidene (T, C or Uracil in RNA).

A – Adenine G – Guanine

T – Thymine C – Cytosine

5.Types of gene interaction

Types of gene interaction	Ratio
Typical di-hybrid ratio for a single trait	9:3:3:1
Duplicate gene action	15:1
Complementary gene action	9:7
Supplementary gene action	9:3:4
Masking gene action	12:3:1
Polymeric gene action	9:6:1
Additive gene action	1:4:6:4:1
Inhibitory gene action	13:3

6.Types Of Aneuploids

Aneuploids:- A loss or gain of one or few chromosome the somatic chromosome number of a species is known as Aneuploids.

7.Organism Used in Genetics

8.Examples Of commonly used mutagens

Class	Mutagens
1. Physical mutagens
Ioning radiations	@-rays, β-rays, γ-rays (¹⁴c, ⁶⁰co),& x-rays
Non-ioning radiations	Non-ioning radiations UV rays
2. Chemical mutagens
Alkalating agents	Mustard gas, EMS, MMS, EES
Base analogues	5-Bromouracil
Acridine dyes	Acriflavin
Deamination agents	Ethium bromide

Mutagens Agents:- both chemical and physical, increase the frequency of mutations several-fold are called mutagens.

9.Contribution of some Geneticists

Geneticists	Contribution
Mendel	Father of Genetics
Bateson	Linkage, Sex determination.
Johannsen W.L.	Pure line, Phenotype and Genotype
Morgan T.H.	Chromosomal theory of heredity
Muller H.J	X-ray – Physical mutant
Avery O.T, MacLeod, C.M. and McCarthy	Bacterial transformation
Watson and Crick	Molecular Structure of DNA
Barbara McClintock	Jumping Gene Transposons
Benzer, S	Unit of functions cistron, Recon and muton
Jacob and Monod	Operon concept
Nirenberg M. W. and Khorana HG	Deciphers the genetic code
Beadle and Tatum	One gene one enzyme hypothesis

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