4. Characteristics of Prokaryotic Cell:-
Prokaryotic cells have different characteristic features. The characteristics of
the prokaryotic cells are mentioned below.
1.They lack a nuclear membrane.
2.Mitochondria, Golgi bodies, chloroplast, and lysosomes are absent.
3.The genetic material is present on a single chromosome.
4.The histone proteins, the important constituents of eukaryotic
chromosomes, are lacking in them.
5.The cell wall is made up of carbohydrates and amino acids.
6.The plasma membrane acts as the mitochondrial membrane carrying
respiratory enzymes.
7.They divide asexually by binary fission. The sexual mode of reproduction
involves conjugation.
Prokaryotes:-
A microscopic single-celled organism which has neither a
distinct nucleus with a membrane nor other specialized
organelles
6. Since organized agriculture developed 4000 years ago, special attention was
given to plant diseases and pests. Symptoms such as blight, wilt, root rot, etc.
were known to the people at that time.
In RigVeda, germ theory of disease was also advocated and the men of
learning inVedic period (Ca. 1500-500 BC) were aware that the diseases were
caused by microorganisms.While this fact was not perceived by majority of the
scientists in Europe only until 120 years ago.
During this period, the plant diseases were attributed to many causes which
included divine power, religious belief, superstitions and effects of stars and
wrath of God, etc.
Antony van Leeuwenhoek observed the micro organismic cells for the first
time under microscope in 1674.
The discovery of microscope led to several advances in the field of Plant
Pathology.
Later in 1878 T. J. Burrill reported that the fire blight of pear is caused by
bacterium Erwinia amylovora.
And hence the branch of PHYTOBACTERIOLOGY cam into existence.
7. History of Bacteriology…..
The historical development is discussed with the pioneering
works contributed by eminent researchers in both basic as well
as advanced studies in field of microbiology ,general
bacteriology and plant bacteriology.
9. 1) AntonVan Leeuwenhoek (1632-1723):-
Developed the first microscope and first described bacteria and called them
‘animalcules’. Most of the animalcules are now referred as unicellular organisms.
Also discovered the vacuoles in cells.
He is known as the ‘Father of Bacteriology’.
10. 2) Louis Pasteur (1822 - 1895):-
He was a French biologist, microbiologist and chemist.
He is renowned for his discoveries of principles of vaccination, microbial
fermentation and pasteurization.
He created first vaccines against rabies and anthrax.
He disproved the age old theory of spontaneous generation.
He is regarded as the Father of Microbiology, Father of fermentation & Father of
pasteurization.
11. 3) Robert Koch (1843-1910):-
German physician and microbiologist.
Father of modern bacteriology.
Identified the specific causative agents of tuberculosis, anthrax and cholera.
He formulated the Koch’s postulates. They are also known as pathogenecity test.
He received the Nobel Prize for his research on TB in 1905.
12.
13. 4) M. S .Voronin(1838-1903):-
Dr. Voronin was the first who conclusively demonstrated the association of root nodule
bacteria with legume plants.
5) M. W. Beijerinck(1888):-
Dr. Beijerinck from Netherland was the first to isolate root nodule bacteria in pure culture from
nodules in legumes named them as Bacillus radicola.
Dr. Beijerinck is considered as father of “microbial ecology”
14. 6)Thomas Jonathan Burrill(1839-1916):-
Professor Burrill was born at Pittsfield
He was the faculty of University of Illinois
He was first to report (in 1878) bacterial etiology of plant disease.
In 1878 he reported that the fire blight of pear is caused by Erwinia
amylovora
15. 6) Edouard Chatton(1883-1947):-
In 1937, Professor Chatton grouped the living domains in two
major empires, namely prokaryotes and eukaryotes.
16.
17. CarlWoese and his associates at University of Illinois discovered novel
prokaryotic organisms , the archeobacteria.
The archeobacteria differed from bacteria in the structure of their cell wall,
plasma membrane and the extreme environment in which they lived.
They were so different in their structure & metabolism that they deserved a
separate place outside the bacteria.
In 1990,Woese suggested a new taxonomic category, the DOMAIN=SUPER
KINGDOM and divided the living world into three domains, BACTERIA,
ARCHEA & EUKARYA.
7)CarlWoese:-
18.
19. 8) David Henricks Bergey(1860-1937):-
Dr. David Bergey was an American bacteriologist.
He was the first doctor to isolate a bacterium called Actinomyces from a
human being in 1907.
In 1923 , he and his four bacteriologist published the first edition of
Bergey’s Manual of Determinative Bacteriology, a fundamentally
important reference book for the identification and classification of
Bacteria
20. 9) Robert Harding Whittaker (1920-1980):-
Prof. Whittaker an American vegetation ecologist , who proposed five
kingdom systems for classification of living organisms.
It includes 1.Kingdom Animalia
2.Kingdom Plantea
3.Kingdom Fungi
4. Kingdom Protista
5. Kingdom Monera
21. 10) Hans Ris (1914-2004):-
Dr. Hans Ris was born in Bern , Switzerland, in 1914.
He coined the term genophore to describe the bacterial nucleus and chromosome
11) OswaldT. Avery (1877-1953):-
Professor Avery’s group in 1944 demonstrated that DNA is a genetic material
of bacteria.
22. The DNA of most bacteria is contained in a single circular
molecule, called the bacterial chromosome. The
chromosome, along with several proteins and RNA
molecules, forms an irregularly shaped structure called the
nucleoid. This sits in the cytoplasm of the bacterial cell.
23. 12) Selman Abraham Waskman (1888-1973):-
Professor Waskman , an American Scientist who in 1944 discovered the
antibiotic streptomycin produced by the Actinomycetes Streptomyces
griseus.
He received Nobel prize in 1952 for this contribution.
24. 13) Hans Christian Gram(1853-1938):-
Dr. Hans Christian Gram , a Danish scientist who devoloped a staining
technique called “Gram staining” in 1884 to discriminate between two
groups of bacterial based on the chemical properties of their cells
walls.
26. 14) JosephW. Kloepper:-
He is considered as father of PGPR(plant growth promoting
rhizobacteria)
He and his co-workers are involved at the basic and applied aspects of
using beneficial bacteria (PGPR and endophytic bacteria)as microbial
inoculants to promote plant growth and to provide biological disease
control
28. 1) Makanji Kalyanji Patel (1899-1967):-
Plant Bacteriology in India got a shape with efforts of Makanji
Kalyanji Patel.
He established a school of Plant Bacteriology at College of
Agriculture ,Pune and first described a new species Xanthomonas
campestris pv. Uppali from the host of Ipomea muricota.
He described more than 30 bacterial diseases from India.
29. 2) G. Rangaswami :-
Professor Rangaswami described the importance of phytobactererial
diseases in India.
He authored a book entitled “ Bacterial Plant Diseases in India.
3) D.N. Srivastava(1925-2008):-
Professor Srivastava is mostly remembered for his tremondous contribution
on bacterial blight of rice
30. 4) Jeevan PrakashVerma (1939-2005):-
Professor Verma’s contribution on ‘Xanthomonas campestris pv.
Malvacearum, the incitant of cotton bacterial blight, led to a solid
foundation to the Indian Phytobacteriology in general and cotton
bacteriology in particular.
He established race identification scheme for cotton bacterial blight
pathogen.
2001 – Jayashree and J.P.Verma brought out a book on “Fundamentals
of Plant Bacteriology”
1987 –Verma wrote a book entitled “The Bacteria”.
31. #1908 –The earliest disease studied in India was tundu disease of wheat. It was
reported by Hutchinson
#1923 – Ballard and Norris reported Angular leaf spot of cotton
# 1927 – Ayyer for the first time reported soft rot of garden poppies
#1928 – Black rot of cabbage caused by Xanthomonas campestris pv campestris
was reported in India by Patwardhan.
#1930 – Soft rot of turnip and leaf spot of cucumber was reported by Prasad.
#1938 – Bacterial pustule of soybean was first reported by Uppal and co workers
#1940 – Luthra and Sattar emphasized the severity of canker disease of citrus.
# 1944 – Asthana and Mahmud for the first time reported leaf spot of pepper.
#1950 – M.K. Hingorani reported about the complex nature of tundu disease of
wheat caused by a bacterium and a nematode and also he confirmed the causal
agent of ring disease of potato as Pseudomonas (=Ralstonia) solanacerarum.
M.K.Hingorani at IARI made valuable contributions for understanding the soft rots
of potato, onion and pea caused by different species of Erwinia.
32. #1960s - 1970s - B.P. Chakravarti carried work out on nutritional requirements of
several bacterial pathogens specific media and developed for the some growth of
Erwinia chrysanthemi pv. zeae and Xanthomonas campestris pv. vesicatoria.
#1962 - D.N. Srivastava contributed for his tremendous work on understanding
the survival and epidemiology of bacterial blight of rice.
#1972 - A.K.Chatterjee and M.P. Starr demonstrated conjugative gene transfer
in phytopathogenic bacteria
#1972 – Anand M Chakrabarty patented the first genetically engineered living
organism Pseudomonas which degrades oil
#1952 – Hingorani and Mehta described the leaf spot disease of pomegranate
from Delhi.
#1959 –The first Indian record of bacterial blight of rice was by M.C.Srinivasan,
M.J.Thirumalachar and M.K.Patel from Maharashtra
33. Organisms that cause plant diseases reduce our ability to
produce food, fiber, and biofuels, and harm the economy. All
plants, from citrus and grains to ornamental shrubs and forest
trees, are susceptible to plant diseases. Plant diseases cause
many billions of dollars worth of direct and indirect losses
every year, threaten food security and have the potential to
hamper tourism. Responding to emerging plant pathogens
requires preparation and planned scientific-based procedures
to lessen the impact on farmers, their communities and the
economy.
IMPORTANCE OF
PHYTOBACTERIOLOGY……
34. Some bacterialdiseasesof plants
Disease Causative agent Hosts Symptoms and signs Additional features
Granville wilt Pseudomonas solanacearum
tobacco, tomato, potato,
eggplant, pepper, and other
plants
stunting, yellowing, and wilting of parts
above ground; roots decay and become
black or brown
occurs in most countries in temperate and
semitropical zones; causes crop losses of
hundreds of millions of dollars
fire blight Erwinia amylovora apple and pear
blossoms appear water-soaked and shrivel;
spreads to leaves and stems, causing rapid
dieback
first plant disease proved to be caused by a
bacterium
wildfire of tobacco Pseudomonas syringae tobacco yellowish green spots on leaves
wildfire of tobacco occurs worldwide;
causes losses in seedlings and field plants
blight of beans Xanthomonas campestris beans (common blight) yellowish green spots on leaves
most phytopathogenic xanthomonads and
pseudomonads cause necrotic spots on
green parts of susceptible hosts; may be
localized or systemic
Pseudomonas syringae beans (brown spot)
small water-soaked spots on lower side of
leaves enlarge, coalesce, and become
necrotic
soft rot Erwinia carotovora
many fleshy-tissue fruits—e.g.,
cabbage, carrot, celery, onion
soft decay of fleshy tissues that become
mushy and soft
occurs worldwide; causes major economic
losses
crown gall Agrobacterium tumefaciens
more than 100 genera of
woody and herbaceous plants
initially a small enlargement of stems or
roots usually at or near the soil line,
increasing in size, becoming wrinkled, and
turning brown to black
the conversion of a normal cell to one that
produces excessive cell multiplication is
caused by a plasmid (a small circular piece
of DNA) carried by the pathogenic
bacterium
aster yellows Mycoplasma-like organism (MLO)
many vegetables,
ornamentals, and weeds
chlorosis; dwarfing malformations
greatest losses suffered by carrots;
transmission by leafhoppers
citrus stubborn disease Spiroplasma citri (MLO)
citrus and stone fruits and
vegetables
chlorosis, yellowing of leaves, shortened
internodes, wilting
first MLO pathogen of plant disease
cultured
