History of Plant Pathology

A detailed history of plant pathology is mentioned, covered various important contributions with diagrammatic representations of scientists and depth include of subject matter has been updated

1. History of plant
pathology
N. H. SHANKAR REDDY
1
st
, Ph.DPlant Pathology
AnnamalaiUniversity

2. The history of plant pathology is divided into different five eras:
•Ancient era : Ancient to 5
th
century (476 A.D.)
•Dark era : 5
th
to 16
th
century (476 A.D. to 1600)
•Pre modern era: 17
th
century to 1853 (1600 to 1853)
•Modern era : 1853 to 1906
•Present era : 1906 onwards.

3. Ancient era : Ancient to 5
th
century (476 A.D. )
Archives in India
•Rigveda, Atharveda(1500-500 B.C.) ,
•ArthaShastraofKautilya(321 –186 B.C.)
•Sushrutasamhitan(200 –500 A.D.)
•Vishnu Puran(500 A.D.)
•Agnipuran(500 –700 A.D.)
•Vishnu dharmottara(500-700 A.D.)
•Raghuvamshaof Kalidas.

4. Theophrastus (370-286 B.C.)
•Considered as ‘Father of Botany’
•books 'Enquiry into Plants'
‘The Nature of Plants’ and
‘Reasons of
Vegetable Growth’
•He told that ‘Plant diseases as the
wrath/ punishment of gods’for wrongs
and sins they had committed.
Theophrastus

5. Democritus (470 B.C.) -He recommended controlling plant blights by
sprinkling leaf extract of olive oil.
Homer (1000 B.C.)–Mentioned therapeutic properties of sulphur on
plant diseases.

6. •Robigalia–Praisethegodtopreventthe
cropfromdestruction,thereligiousceremony
wasinitiatedbytheKingNumaPompilus
andincorporatedintotheChristiancalendar
asSt.Mark’sDayorRogationonApril25
andthepeoplesacceptthespontaneous
generation,Rubi-Red

7. Albert magnus(1200 A.D.) –
•Recognisedthefirstplantpathogeninthe
world–Mistletoe
•Recommendedculturalmethods(Pruning)
forcontrolofMistletoe
•Commonmistletoeandleafymistletoe
•Europe–Viscum
•NorthAmerica–Phoradendron
•Dwarftmistletoes–Arceuthobium(affected
conifers)
Nicander(185 B. C) –Called mushroom, the
evil ferments of the earth

8. 1670 –Thoullier(French Physician)–Ergotismor Holy Fire

9. ❑Ergot–argot(French)–means“spur”–Clavicepspurpurea
❑Symptomscausedtohumans–reddeningandblistering,excruciatingpaininthe
lowerabdomen,musclespasms,trembling,shaking,convulsions,hallucinations,
permanentinsanity,gangrene,lossoffingersandlimbsandcausedeath
❑“Devil’scurse”,“Fire”,“Holyfire”,“St.Anthony’sfire”
❑Ergotalkaloids–LSD(Lysergicaciddiethylamide)
❑1960–youngturkeybirdsaffectedbythediseasebyfullymoldfeed–TurkeyX
disease
❑1978–gangrenousergotismoccurredinEthiopia

10. 1601 -Clusius–
•Watercolourdrawingsofmushrooms
•Hisbookwas“RaroiumPlantarum
Historica”
1665 -Robert hook [1635 -1703]
•DrawnsporangiaofMucorand
TelisporesofPhrgmidiumdisciflorum,
phragmidiummucronatumandfirst
observedunderMicroscope.
•Wroteabook“Micrographia”in1665.
•Inventedthedouble-lensed(compound)
microscopewithwhichheexaminedthin
slicesofcorkandcalleditsunits“cells”.

11. Carolusvan Linnaeus –Sweden -(1707 -1778) –
•Introduced“BinomialSystemofNomenclature”
•‘Ascandalofart’(Orderingoffungi)
•Publishedhismainwork‘SystemaNatura’in1735
•HisBook“SpeciesPlantarum”publishedin1753
•StudentsareC.H.PersoonandE.M.Fries

12. 1729 -Pier Antonio Micheli (Italy)-
•“FounderandFatherofmycology”
•Hewroteabookcalled“NovaPlantarum
genera”in1729
•Provedthatdiseaseiscausedbyspores
•Described900fungi
•Healsoprovedthatifthesesporesare
placedonapieceoffruits(melonsand
pears)
•theygrowintoanewthallusofthefungus

13. 1761-1836 -C. H. Persoon(France)-
•“FoundingFatherofsystemicmycology”,
•“Foundingfatherofmoderntaxonomyof
mushrooms”(Taxonomyofmushroom)
•basedonsporecolourandarrangementofthe
Hymenophore)
•Articleoffungi(1973),introducedhis
classificationsystem(1794),
•Published“Synopsismethodicafungorum”
(1801)achiefstartingpointforthenamingof
fungi
•SoldhisherbariumtoDutchgovernmentin
1825duetohispoverty

14. ❑1859–CharlesDarwin(Englishman)–showedspeciesofallorganism
❑Book–TheoriginofspeciesbymeansofNaturalselection

15. E.M. Fries (Sweden) -
•Linneausofmycology,Fatherofsystemicmycology
•Wroteabookcalled“Systemamycologicum”in1821(startingpointin
nomenclatureoffungi)
•RegardedtheRustandSmutfungiasproductsofdiseasedplants
•Basidiomycotaisdominatedwith“Friesianapproach”

16. MatheiuDuTillet,1755
GreatGrandfatherofPhytoPathology.Buntof
wheatisacontagiousdisease(externaltransmission
ofbunt)andheshowedthatbuntaffectedseeds
treatedwithwatercontainingsaltandlime
producedalowerpercentageofdiseasesplants.

17. 1840 -TulsaneBrothers(Paris)-
•L. R. Tulsaneis Considered as “Reconstructorof
mycology”
•Recognised the five spore stages of Autoecious
(single) rust fungus in 1854
•Book “ Selecta FungorumCarpologica” (1861 –
1865)
Charles Tulasne

18. 1858-J. G. Kuhn (Germany)-
•Published 1st text book in plant
pathology “ The diseases of cultivated
crops, their causes and their control” in
1858
•Considered as ‘Microscopic manager’

19. M. J. Berkeley(England)-
•Coined the term “ Mycology”
•Systematistto mycology with 6000 species
•Published “Introduction to CryptogamicBotany” in 1857
• “ Outlines of British fungology”in 1860
•Began the publications of “Vegetable Pathology” in 1854
•Given "Oidiumtuckerii” to grape powdery mildew

20. Modern era
1831-1888 -Heinrich Anton De Bary (Germany):-
•He was a German surgeon, Botanist, Microbiologist, and Mycologist
•Largely Considered as “ Father of Plant pathology”, “Father of Modern Plant
•Pathology” and “Father and Founder of modern Experimental Plant Pathology”
•He wrote a books are “Comparative Morphology and the Biology of Fungi, Myceteoza
and bacteria” (1866)
“Lectures on bacteria” 1885
“On Mildew and Fermentation” 1872
“Comparative Anatomy of the Vegetative Organs of the Phanerogamsand Ferns
“Morphologie und Physiologie der pilze, Funchten und Mycomycetes” in 1866,
English translation happens in 1887, Authorised translation by Henry E. F.
Garnsey. Revised by Isaac BayleyBalfour

21. •Introducedtheterms”Haustoria/Sinkers”,”Symbiosis”,
”Teletospores”,“Myceteoza”,“Sexhormone”,(Sirenin,
Antheridiol),AutoeciousandHeteroeciousrust,and
“Chlamydospores”
•HisstudentsareM.S.Woronin(Russia),O.Brefelds
(Germany),A.Millardet(France),H.M.Ward(England),
W.G.Farlow(USA)andFisher(Switzerland)
•DiscoverdthelifecycleofPhytophthorainfestans(late
blightofpotato)thatcausesIrishfamine.
•Demonstratedtheheteroeciosnatureofstemrustofwheat
in1865.
•1stphysiologicalplantpathogenworkon‘Botrytiscineria
•Reportedtheroeofenzymesandtoxinsin‘direct
penetration’bytissuedegradation
•Sclerotiniasclerotiorumin1886.
•PhytophthorameansPlantdestroyer

22. 1878 –M. S. Woronin (Russia)-
•Discovered and named the Club root of
Cabbage pathogen as Plasmodiophora
brassicaein 1875
•Found out the life cycle of potato wart
(Synchitriumendobioticum) disease in 1878.
•Discovered the Woroninbodies.

23. 1880 H. M. Ward (England) -
•“Father of Tropical Plant Pathology”
•Emphasises the Role of environment on
epidemiology of coffee rust gave the bridging
host theory in 1903
•Recognised necrotic active defence in
Bromus, later known as hypersentive
response

24. 1882-1885 PMA Millardet(France)-
•Discovered “Bordeaux mixture” for the control of
downy mildew of grapes
•This discovery is considered as serendicity
discovery (accidental discovery)
•Bordeaux mixture Composition 1:1:100 (1kg of
copper sulphate, 1kg of hydrated lime, 100lit
water)
•The original formula developed by Millardet
contains 5 lbsof CuSO4 + 5 lbsof lime 50
gallons of water.
•“Bordeaux” (founded in June 7, 1441 ) is the
university name in France.

25. 1894 –Erikson(Sweden) –
described the phenomenon of
physiological specialization of
wheat stem rust fungus (Puccinia
graministritici)

26. 1845-1920 –Pier Andrea Saccardo (Italy) –
•Professor at Paudauniversity (Italy) developed spore
group system for Ascomycetes(Sac fungi) and
Duteromycetes( Dust bin fungi/ fungi imperfecti) fungi
and systematically arranged and initiated systemic
grouping of fungi
•His famous book is “ Syllomefungorum”(1882-
1931,1972) ( 26 volumes )
•Most of the books mentioned 25 volumes, originally its 26
volumes of work]
•Full name is “Syllomefungorumomniumhucusque
cognitorum”
•Saccardo’sother important treatise “ fungi italic “ (1877-
1886) appeared in 38 volumes

27. 1886-1971-J. F .Dastur –
•FirstIndianplantpathologist,
internationallyknown forthe
establishmentofgenus
•Phytophthoraanddiseasescausedby
castor(Phytophthoraparasitica)and
potato
•1stpresidentofthe“Indian
PhytopathologicalSociety”(IPS)in
1948.
•Reportedthe1stplantviraldiseasesin
India(Sugarcanemosaicvirus)

28. 1874-1943 –Edwin John Butler
(Ireland)-
•1st ImpericalMycologist in India
•Considered as ‘ Father of modern plant pathology in
india”, “ Father of Indian mycology”
•First director of the “Impericalbureau of mycology” in
England from 1920-1935
•His book was “ Fungi and Disease in Plants” in 1918
•Monograph on “Pythiaceousand allied fungi”
“The fungi of India” (along with
Guy and Richard Bisby) in 1931
“Plant Pathology (with S.G. Jones)”
•Discovered genus “Allomyces”
•Reported bangle blight of potato (1
st
record of bacterial
disease in India)
•He was appointed as the first CryptogamicBotanist to the
Government of India at Calcutta

29. Elvin Charles Stakman(USA) –
•Distinguished biological forms of cereal rust
•Coined the term “hypersensitivity”(Autolysis)
•(hypersensitive reaction -abnormal death of host cells
when attacked by rust) in 1915
•Demonstrated physiological forms of stem rust of
wheat in 1917
•Also studied the air dispersal of rust fungus in 1920s

30. 1927-J. H. Craigie(1887-1989) –
•Discovered the sexual stage of rust fungus as Pycniaor
Spermatia( “0” stage )
•Discovered heterothallism of Pucciniagraministo
reveal the function of pycniumas sexual organ

31. 1928 –Alexander Fleming (United Kingdom) –
•Isolated Penicillin from Pencilliumnotatum(now called as Peniciliumchrysogenum)
•Shared noble prize in Physiology and medicine along with Ernst B. Chain & Howard
Walter Florey in 1945
•When I woke up just after dawn on September 28, 1928, I certainly didn't plan to
revolutionise all medicine by discovering the world's first antibiotic, or bacteria killer.
But I suppose that was exactly what I did. —Alexander Fleming

32. 1929 –J C Walker –
•IdentifiedCatecholandProtocatechuicacidasa
preformeddiseaseresistancefactorsagainst
onionsmudge(Colletotrichumcircinans)disease
(redonionbulbs)
•Duetophenoliccompoundstheonionsare
resistantagainstsmudgediseases
•Firstscientisttodemonstratethe“chemicalnature
ofdiseaseresistanceinplants".
•Walkerismostknownfordevelopingdisease-
resistantvarietiesofonions,cabbages,beans,
peas,beetsandcucumbers

33. 1933 –K. C .Mehta –
•Consideredas“FatherofIndianRust”
•DiscoveredthelifecycleofstemrustofwheatinIndiaand
reportedthebarberry(alternatehost)
•Publishedtwomonographs“Furtherstudiesoncerealrust
inIndia”Part1(1940)andPart2(1952)
•EstablishedthreelaboratoriesforrustresearchatAgra,
AlmoraandShimla.

34. 1940 –K. O. Muller and H. Borger –
•Coined the term “Phytoalexins”( antimicrobial compounds in plants)
•The 1
st
phytoalexinis “Pisatin”(produced from Pea plant), The molecular formula is C
17H
14O
6
1940 –Paul Neergaard(Denmark) –
•Consideredas“FatherofSeedPathology”alongwithMaryNoblecoinedtheterminthe1940s
•Authoredabook“SeedPathology”in1977(2volumes)
•HeservedastheChairmanofthePlantDiseaseCommitteeoftheInternationalSeedTestingAssociation
(ISTA)from1956to1974

35. 1946 -Harold Henry Flor–
•Gavegeneforgenehypothesisofplant-pathogengenetic
interactionwhilstworkingonrust(Melampsoralini)offlax
(Linumusitatissimum)
•Heproposedtheterm"Avirulencegene"(Avr)
•Geneforgenehypothesis:-Oneisaplantgenecalledthe
resistance(R)gene.Theotherisaparasitegenecalledthe
avirulence(Avr)gene.PlantsproducingaspecificRgene
areresistanttowardsapathogenthatproducesthe
correspondingAvrgeneproduct.

36. 1947 –B. B. Mundukur–
•StartedIndianPhytopathologicalSoeiety
(IPS)
•WorkedoncottonwiltinBombaystate,
publishedUstilaginalesinIndia
•Firstissueofthejournal“Indian
phytopathology”in1948
•Publishedatextbook“Fungiandplant
diseases“in1949,whichwasasecond
bookofplantpathologyafterButller

37. 1952 –G. Pontecorvoand JA Roper -
•DiscoveredparasexualityinAspergillus
nidulans
(parasexuality:-plasmogamy,karyogamyand
meiosisnotoccursinaregularstage/manner)
•JARoperreportedthehormonalcontrolof
sexualityinfungi

38. 1963 –J. E. Vander Plank –
•Considered as “Father of Epidemiology”
•Gave the concept on horizontal and vertical resistance in plants in
1968
•Coined the term “ Vertiofoliaeffect ”to describe horizontal
resistance
•(Vertifoliaeffect –loss of horizontal resistance during breeding for
vertical resistance in the German potato variety ‘Vertifolia’ with late
blight resistance set the scentesnse
Published “Plant Disease Epidemics and Control ” in 1963
“Diseases Resistance in Plants” (1968)
“Principles of Plant Infection” (1975)
“Genetics and Molecular Basis of Plant Pathogen” (1978)
“Host Pathogen Interaction in Plant Disease” (1982)

39. 1964 –Norman E. Borlaug (USA) –
•Developed semi-dwarf, high-yield stem rust resistant wheat
varieties
•He was often called “ The father of the Green Revolution”
•he was awarded the Noble Peace Prize in 1970 in recognition of
his contributions to world peace through increasing food supply
•He worked in the fields of Agronomy, Plant pathology and
Genetics
•( Ph.D. in plant pathology and genetics)
1964 –M. J. Thirumalachur–
•He was known for the development of antifungal antibiotics such
as Aureofungin, Hamycin, Dermostatin, MYc-4 and tertaenenin.
•Book “ Antibiotics in Plant Disease Control ”
•Conducted extensive studies in rusts and smut
•Wrote monograph on “ Ustilaginalesin India, Uredinalesof the
world, Cercosporae, Physodermaand Cephalosporium

40. 1976. JacoovKatan(Israel)-
•“Father of soil solarisation”
•Originally developed solarisation (solar heating of the soil) to control soil borne
pathogens (Ex: Damping off –Pythiumapanidermatum)
•Suggested Polythene bag size -100 microns)

41. 1989 –M.B. Dickmanand P.E. Kolattakudy–
•Successfully transformed a wound infection fungus with a gene coding for enzymes
cutinasedegrading cuticle for penetration
•Demonstrated the function of enzyme cutinasewhich are responsible for direct
penetration of pathogen
•The cutinasegene from Fusariumsolanif.sp. pisi(Nectriahematococa) was cloned and
sequenced.

42. 1990. DF Klessigand I Raskin; JP Metrauxand J Ryals
DemonstratedcrackingconceptthatSalicylicacidisassociatedwithSystemic
AcquiredResistance(SAR)
1991.R.BroglieandR.Chenetal-
•Theplanttransformedwithchitinasegene(Genesthatcodesforchitinase)exhibit
enhancedresistancetodiseasebyfungithatcontainschitinintheircellwalls.
•Demonstratedincreaseddiseaseresistanceintobaccoplantsbytransferringgene
•Stilbenesynthetase,theenzymethatsynthatisephytoalexinandexhibitenhanced
diseasesresistance

43. 1991. PJ GM De Wit et al -
•Cloned/isolated1stfungalavirulentgenefromCladosporiumfulvum(CF9,avr6)
1992.SP.Briggs,JDWaltonetal–
•Clonedthefirstresistancegene(Hm-1)fromcorndemonstratedthatitsprotein
productdetoxifiedthehostselectivetoxinofCochlioboluscarborum
2005.RADeanetal(CentreforIntegratedFungalResearch,NorthCarolinaSate
University,USA)
•ThefirstcompletegenomesequencedofaplantpathogenicfungusMagnoporthe
grisea

44. bacteriology
Ehrenberg –Coined the term “Bacteria”
1665–Francesco Redi(Italy) –
•“FounderofExperimentalBiology”and“Fatherof
ModernParasitology”
•1
st
disapprovedtheSpontaneousgenerationtheory(He
wasthefirstpersontochallengethetheory
ofSpontaneousgenerationbydemonstrating
thatmaggotscomefromeggsofflies)
•ExperimentsontheGenerationofInsects,publishedin
1668.

45. 1675 –Leeuwenhoek–
•Developed 1
st
microscope, Considered as
‘Father of Bacteriology’
•Developed hundreds of microscopes and obtain
a magnification of 50-300 diameters.
•Also discovered the Spermatozoa and the red
blood cells
•1
st
publication in bacteria was in 1683
(Dear god what marvels they are so small a
creature –Leeuwenhoek)

46. 1858 –Louis Pasteur (France) –
•Fatherof“ModernBacteriology”and“Founder
ofMicrobiology”
•Formulatedgermtheoryofdiseasesand
demolishedthespontaneousgenerationtheory
•Developed the principles
of vaccination, microbial
fermentationandpasteurization.
•CreatedthefirstvaccinesforRabiesandAnthrax
•(Pasteurization:-Heat-treatmentprocessthat
destroyspathogenicmicroorganismsincertain
foodsandbeverages.
•Fermentationofwineandbeerisabout57°C
(134.6°F)forafewminutes.Pasteurization
ofmilkofabout62.8°C(145.04°F)for30
minutesor,alternatively,heatingtoahigher
temperature,72°C(161.6°F),andholdingfor15
seconds,

47. RobertHeinrichHermanKoch1890-
•FatherofModernBacteriologicaltechniquesand
microbialtechniques
•‘Founderofmodernbacteriology’.
•ProposedtheKoch’sPostulatesandpureculture
technique.
•Firstbacterium–Bacillusanthracis

48. E.F.Smith1901-1920
•Finalproofthatbacteriacouldcausethedisease,
•Workedonbacterialwiltofcucurbits(1896)andcrown
gall(1911).
•“FatherofPhytobacteriology”
•Book:“BacteriainRelationtoPlantDiseases”in1905,
1911and1914,“IntroductiontoBacterialDiseasesof
Plants”in1920.

49. •1877 –Nageli–Suggested that pleomorphismin bacteria, which
refers the existence of a single species in several morphological
forms, which is accepted by most bacte
•1878 –Se’dillot–French retired army surgeon , coined the term
“microbe”riologistsin his time

50. T.J. Burrill1882-
Founder of Phytobacteriology, identified first bacterial disease Erwinia
amylovorain apple and pear.

51. 1884 –Christian Gram-
•Developedbacterialstainingtechnique
•Basedonstainingbacteriacanbe
dividedintogrampositive(+ve)and
gramnegative(-ve)

52. •F. W. Twort(1915), F. D’ Herelle(1917) –Discovered Bacteriophage
individually.
•1923 –“Bergey’sManual of Determinative Bacteriology” was published
(David H. Bergy)
•1925–Johnsonand WF Murwin–Demonstrated the role of toxin in
wild fire disease of Tobacco caused by Pseudomonas syringaepv. tabaci
•1925 –G. H. Koonsand J. E. Kotila–Isolated bacteriophages of
Bacillus caratovorus

53. Selman A. Waksman–
•Considered as “Father of soil
microbiology” and “Father of
antibiotics”
•Discovered the antibiotic
‘Streptomycin’ (Streptomyces griseus)
in 1943
•Awarded Noble Prize in Physiology of
Medicine in 1952 (for the discovery of
streptomycin)

54. 1946–J. Lederbergand Edward Tatum-
•Discovered the bacterial Conjugation in
Escherichia coli.
•Coined the term ‘plasmid’
•Lederbergreceived Nobel prize (physiology
and medicine) in 1958 for his discoveries
concerning genetic recombination and the
organization of the genetic material of bacteria

55. 1964 –Z. Klemment–
•Recognised the hypersensitivity response (HR) in bacterial pathogens
•(Hypersensitive response:-plantdefenceresponseis the induction of
programmed cell death, Autolysis happens to prevent the diseases spread)
1977 -M. D. Chilton et al -Introduced DNA plasmid of Agrobacterium
tumefaciensinto Cells of higher plants

56. 1984 –BJ Staskawicz-
•Cloned the first Avirulentgene from Pseudomonas syringaepv. glycinea
DC300
•Provodedthe first molecular evidence in support of the “gene-for-gene’
hypothesis for plant pathogenic response
•Done this experiments along with his long-time friend Noel Keen (coined the
term elisitor)

57. virology
1886 –Adolf Mayer (Germany)-
•Coined the term ‘Mosaic’
•He thought that the causal agent was the bacteria.
•First to prove the transmissible plant virus i.e. TMV
•He called sap transmission of tobacco disease is
‘Mosaikkrankheit’
•Later he performed experiments with Chamber land filter
paper, even though the virus retains infectivity.
•He taught that the causal agent was the bacteria.

58. 1892 –D. Ivanovsky(Russia) –
•Proved that the causal agent of tobacco mosaic disease could
pass through bacteria proof filters.
•Concluded that the causal agent of tobacco mosaic (virus) is
smaller than bacteria.
•1
st
man who discovered ‘inclusion bodies’
•Described the horizontal transmission of plant viruses

59. 1898 –Beijerinck–
•Dutchmicrobiologistandbotanist.
•Founder and Father of Virology / Father of Environmental
Ecology
•Performed agar diffusion experiments and coined the term
‘Virus’
•He called the liquid material of virus is “Contagiumvivum
fluidum”which cause the repeated infection in Tobacco
mosaic virus
•He also worked on nitrogen fixation in which Nitrogen is
converted into Ammonium
•The first known sulfate-reducing bacterium, was isolated
and described by Beijerinck(Spirillumdesulfuricans, now
called asDesulfovibriodesulfuricans)
•Clostridium beijerinckiiis agram positive,rod
shaped;motilebacterium was named after Beijerinck.

60. 1915 –Twort, 1917 -F. D. Herelle–Individually
discovered bacteriophages
1929 –Holmes –Developed local lesion assayin
Nicotianaglutinosa
•(Local lesion assay-A tool by which virus could be
measured by showing that the amount of virus
present in the plant sap preparation is proportional to
the number of lesions produced on appropriate host
plant leaves rubbed with the sap)
•Observed that single dominant gene controlling the
hypersensitive reaction (HR) and proposed the “viral
hypersensitivity”. Single dominant gene
subsequently transferred from N. glutinosato N.
tabacumin which the TMV resistant cultivars are
produced

61. 1929 –Mckinney–
•Developed cross protection/ pre-immunization technique for control of citrus
tristezavirus (CTV)
•Cross protection was 1
st
used against TMV

62. 1931-1933 -Knoll and Ruska-
•ThefirstprototypeofelectronmicroscopewasdevelopedbyErnst
Ruska(1931)andKnollwhichiscapableof400magnificationpower
•Then,Ruska(1933)builtthefirstelectronmicroscopethatattainshigh
resolutionwithanoptical(light)microscope.
•HewontheNobelPrizeinPhysicsin1986forhisfundamentalwork
inelectronoptics,includingthedesignofthefirstelectronmicroscope.

63. 1935-W. M. Stanley –
•Americanbiochemist,virologist
•Done Purification/ Crystallisation of virus (by using
ammonium sulphate)
(Preparation of enzymes and virus proteins in a pure form)
•He received Nobel Prize in 1946 (for crystallisation of virus)
•He believed that virus was an autocatalytic protein that could
multiply with in the living cell
•Molecular plant pathologywork can be initiated with W. M.
Stanley work
•(Note-X-ray diffraction studies by J.D. Bernal and I.
Fankuchenshowed that they are true three dimensional
crystals, they were paracrystallineand that the rod like virus
particles.

64. 1936 –F. E. Bawdenand N. W. Pirie –
•Demonstrated that virus is a nucleoprotein which
consists both nucleic acid and protein
•They also purified/ crystallised TMV in 1936 (after
W. M. Stanley experiment), further purification of
protein in neutral aqueous solution can be obtained
in liquid crystalline states.
•First suggested that virus replication might be
analogous to the synthesis of cellular components
(1936)
•Detect that phosphate is inherent part in RNA
molecule.
•Their studies reveals that 1-2gm of protein can be
isolated from a litre of sap, it depends based on the
age of the plant and duration of infection

65. 1952-1953 –Watson and Crick –
•Discovered the double helical structure of DNA, in which their discovery
revolutionized the entire biology.
•They contended that all viruses must be built up symmetrically from identical protein
subunits that surround the nucleic acid in 1956
•General theory of structure of capsid of virus; the coat protein made up of numerous
identical subunits as heliclerods or spherical shell.
•Got noble prize in physiology and medicine in 1962

66. 1956 –Gierrerand Schramm –
•Showed that nucleic acid is the infectious agent
•(Showed that only nucleic acid of TMV is infective and protein coat does not
•have any role in infection, Nucleic acids carry hereditary information and that
•nucleic acid alone is sufficient for viral infectivity)
•Also investigated about double standard RNA viruses (ds RNA)

67. 1975–Kohler and Milstein-
Developed “Hybridomatechnology” in
monoclonal antibodies production –
Nobel prize in 1984.
1976 –Volleret al,1977 –Clark and
Adams –Developed ELISA technique
and used ELISA in Plant virus
detection.
1984-Prusiner-
•Discovered of Prions in animals:
•Received Nobel Prize in 1997 in
physiology of Medicines for the
discovery of ‘Prions’ and biological
principles of infection

68. 1998 -Andrew Fire & Craig Mello –
•First described their work on RNA interference Gene silencing by
dsRNA, in the nematode Caenorhabdatiselegans.
•RNA interference is traditionally/ otherwise called as Post
transcriptional gene silencing (PTGS)
•shared Nobel prize in 2006.

69. The man who studies history can makes history

70. The man who studies
history can makes
history