Origin of Cultivated plants, Crop Domestication and Germplasm Diversity

This PPT intends to explore the different fundamental aspects of economic botany like crop domestication, germplasm etc.

1. WELCOME TO ECONOMIC BOTANY
Origin of Cultivated Plants : Concept of Centres of Origin,
their importance with reference to Vavilov’s work.
Examples of major plant introductions; Crop
domestication and loss of genetic diversity; evolution of
new crops/varieties, importance of germplasm diversity.
By
N. Sannigrahi, Associate Professor,
Department of Botany,
Nistarini College, Purulia (W.B) India

2. ECONOMIC IMPORTANT PLANTS

3. INTRODUCTION
Thebasicneedsofthehumanbeingsarefood,clothing&
shelter.Thealltheaboveindispensibleitemsareobtained
fromplantsdirectlyorindirectly.Theangiospermsalongwith
manyfungi,algae,bryophytes,pteridophytesand
gymnospermsplayaverycrucialroletoaddresstheabove
needsofthecivilization.Theycanbegroupedasfollows:
Foodplantcereals
LegumesforpulsesNuts
Fruitsofdiversetypes
Fiberyieldingplants
TanninsandDyes
Rubberanditsdiverseproducts
Fattyoils&vegetablefats,
Essentialoils

4. ECONMIC BOTANY
Organicacids
SugaryieldingPlants
Pulp&paper
Gums&resins
Mucilage
Proteins
Medicinalplantsanddrugs
Foodadjuncts
Apartfromthese,therearealsomanyplantsofgreat
economicimportancewhicharedirectlyusedfromtheplants
orbytheprocessing,differentsecondaryproductsare
availableandallthesesubstancesareusedforthe
developmentofcivilizationandtodrivethewheelof
economyofanycountry.Theplantorplantpartsusedforthe
welfareofhumanbeingsareaddressedinthedomainof
economicBotany.

5. PRIMARY AND SECONDARY ORIGIN
Alltheagriculturalcropshavebeenoriginatedfrom
wouldancestorbutitisverydifficulttofindoutthewild
ancestorsandlociofthedomesticationofeconomic
importantplantsasmostofthemweredevelopedinthe
remotepast.Manystartedtodomesticatethecropsinthe
ancientpasts.DeCandolle(1883)usedmany
archeologicalandethnologicaldata,historicalfindings
andphilogytodeterminetheoriginandthespreadofthe
cultivatedplantsusedintherecenttimes.Butitis
generallyacceptedthatcultivatedplantswerenot
distributeduniformthroughouttheworldandeventoday,
certainregionsshowgreaterdiversitythanother
cultivatedcropplants.Theseareasarecalledtheprimary
centreoforiginandthoseplantsshowingconsiderable
diversityinformsbutnotbeingoriginatedthereare
treatedassecondarycentreoftheoriginofthatspecies.

6. CROP DOMESTICATION
Thecentreoforiginisageographicalareawheretheparticular
groupoforganisms(eitherdomesticatedorwild)first
originatedonearth.Manypeoplebelievedthatcentersoforigin
arealsocentersofdiversity.But,thecentersofdiversitymay
notrepresentthecentersoforiginofcropplants.Althougha
fewspeciesmayhavebeenoriginatedseparatelyatmorethan
oneplace,butmostspecieshadtheiroriginatacertainplace
andthenspreadelsewhere.Inotherwords,inthecentreof
originacropisgenerallyconfinedtooneplace,whereasthe
centreofdiversitymaybefoundatmorethanoneplace.The
exactlocationoforiginofspeciesisonlyamatterof
speculationbasedonindirectevidences.Theinformationon
originofcropplantsisimportantinplantbreedingtolocate
wildrelatives,relatedspeciesandnewgenes.Knowledgeof
theoriginsofcropplantsisimportanttoavoidgeneticerosion,
thelossofgermplasmduetothelossofecotypesandhabitat.

7. CROP DOMESTICATION

8. VAVILOV SYNDROME
TheRussianscientistNikolaiIvanovichVavilovandhis
colleaguesvisitedseveralcountriesandcollectedalarge
numberofcropplantsandtheirwildrelatives.Theyusedthis
collectioninRussianbreedingprogrammeofdeveloping
improvedvarieties.Hisdeductionswerebasedonevidences
frommorphology,anatomy,cytology,genetics,plant
geographyanddistribution.Heconsideredthatgreatcentersof
originwerealwayslocatedinlowermountainsandhillsof
tropical,sub-tropicalregions.Healsorecognizessome
secondarycentersoforiginwheretwoormorespeciescrossed
together.Secondarycentersoforiginaretheplaceswhere
naturalandartificialselectionoccurredonafteranother.He
statedthatplantswerenotdomesticatedatrandombutitwasa
continuousprocess.

9. VAVILOV CENTRES OF ORIGIN
1.Chinesecentre:Itisconsideredtobeoneofthe
earliestandlargestindependentcentersoforiginof
cultivatedplants.Thiscentreincludesmountain
regionsofcentralandwesternChina.Theendemic
specieslistedfromthiscentreincludeSoyabean,
radish,Turnip,Pear,Peach,Plum,Colacasia,
Buckwheat,opiumpoppy,brinjal,apricots,oranges,
chinateaetc.
2.Himalayancentre:ItalsoknownastheIndian
centreoforigin.ThiscentreincludesregionsofAssam,
Burma,Indo-chinaandMalayanArchipelago.The
endemicspecieslistedfromthiscentreincludeRice,
redgram,chickpea,cowpea,Mungdal,brinjal,
cucumber,sugarcane,blackpepper,Mothbean,rice
bean,cotton,turmeric,indigo,milletsetc

10. VAVILOV CENTRES OF ORIGIN
3.Mediterraneancentre:Thiscentreincludesbordersof
MediterraneanSea.Mostofthecultivatedvegetableshavetheir
origininthisregion.Theendemicspecieslistedfromthis
centreincludeDurumwheat,emmerwheat,oat,barley,lentil,
pea,grasspea,broadbean,cabbage,asparagus,peppermint
etc.
4.Abyssiniancentre:ThisregionincludesEthiopiaandpartsof
Somalia.Theendemicspecieslistedfromthiscentreinclude
Wheat,sorghum,bajra,safflower,castor,broadbean,okra,
coffeeetc.
5.CentralAsiancentre:Thiscentreincludesnorth-westIndia,
Afghanistan,UzbekistanandwesternChina.Theendemic
specieslistedfromthiscentreincludeBreadwheat,clubwheat,
sesame,linseed,muskmelon,carrot,onion,garlic,apricot,
grape,hemp,cottonetc

11. VAVILOV CENTRES OF ORIGIN

12. VAVILOV CENTRES OF ORIGIN
6.Asiaminorcentre:ThiscentrecoversnearEastAsian
regionslikeIranandTurkmenistan.Theendemicspecieslisted
fromthiscentreincludeWheat,rye,Pomegranate,Almond,
Fig,Cherry,Walnut,AlfaAlfa,Persiancloveretc.
7.CentralAmericancentre:Thiscentreincludessouthernparts
ofMexico,CostaRica,GuatemalaandHondurasregion.The
endemicspecieslistedfromthiscentreincludeMaize,rajma,
limabean,melon,pumpkin,sweetpotato,arrowroot,chilly,
cotton,papaya,guava,avocadoetc.
8.SouthAmericancentre:ThiscentreincludesPeruvian
regions,islandsofsouthernChile,BrazilandParaguayregions.
TheendemicspecieslistedfromthiscentreincludePotato,
sweetpotato,limabean,tomato,papaya,tobacco,quinine,
cassava,rubber,Groundnut,Cocoa,pineappleetc

13. LIMITATIONS OF VAVILOV
Theexpansionofourunderstandingoncultivatedplants
pointedcertainlimitationsonVavilov’sviews.Theseviews
requiresomemodifications,1.Vavilovconsideredtheregion
withgreatestgeneticdiversityofaspeciesasthecentreof
originofthatspecies.Butnow,manysuchspeciesareknown
whosecentersoforiginandgeneticdiversityaredifferent.For
example,MaizeandTomato
2.ThecentersoforiginofcultivatedplantsasperVavilovare
limitedtothemountainsandsmallhillsintropicalandsub-
tropicalregions.Butrecentevidencesalsosuggestplainsasthe
centersoforiginofmanycultivatedplants.
3.Todayseveralcropsareknownwhosecentersoforiginare
differentfromtheonessuggestedbyVavilov.Moreoverthereis
morethanonecentreoforigin.Also,theoriginofmanyofthe
speciescannotbetracedduetolackofsufficientevidence

14. MAJOR PLANT INTRODUCTIONS
Plantintroductionisaprocessofintroducingplants(a
genotypeoragroupofgenotypes)fromtheirownenvironment
toanewenvironment.Theprocessofintroductionmayinvolve
newvarietiesofcroporthewildrelativesofcropspeciesor
totallyanewcropspeciesforthearea.Theprocessofplant
introductionisthesuccessfulcomplianceoftwoimportant
aspects,viz.,domesticationandacclimatization.Domestication
istheprocessofbringingofawildspeciesundercultivationby
makingthemchangedinbehaviorsuitablefornew
environment.
Acclimatizationistheabilityofacroptobecomeadaptedtoa
newclimaticandedaphiccondition.

15. PRIMARY & SECONDARY
PrimaryIntroduction:Whentheintroducedvariety
iswellsuitedtonewenvironmentthenitisreleased
forcommercialcultivationwithoutanyalterationof
genotype.Forexample,dwarfwheatvarietieslike
‘Sonora-64’,‘Lermarojo’anddwarfricevarietieslike
‘TaichungNative1’,‘IR-8’aretheexamplesofprimary
introduction.
Secondaryintroduction:
WhentheintroducedvarietyissubjectedtoSelection
orusedinhybridizationprogrammewithlocal
varietiestogettheimprovedvarietieswithsomenew
charactersintroducedcalledsecondaryintroduction.
Forexample,thevarietieslike‘KalyanSona’and
‘Sonalika’ofwheathavebeenselectedfrommaterial
introducedfromCIMMYT,Mexico.

16. CROP DOMESTICATION & LOSS OF GENETIC
DIVERSITY
Cropdomesticationistheprocessofartificiallyselecting
plantstoincreasetheirsuitabilitytohumanrequirements:
taste,yield,storage,andcultivationpractices.Thereis
increasingevidencethatcropdomesticationcanprofoundly
alterinteractionsamongplants,herbivores,andtheirnatural
enemies.Theprocessofcropdomesticationisdrivenbyhuman
selection,cultivationpractices,andagriculturalenvironments.
Anyselectionimposesthereductionofdiversityingenomic
regionscontrollingdesirabletraits,suchasnon-shattering
seedsorincreasedpalatability.Furthermore,agricultural
practicesgreatlyreducedeffectivepopulationsizesofcrops,
allowinggeneticdrifttoaltergenotypefrequencies,including
therandomlossofalleles.

17. DOMESTICATION & GENETIC EROSION
Domesticationimpliestheactionofselectivesweepson
standinggeneticvariation,aswellasnewgeneticvariation
introducedviamutationorintrogression.Furthermore,genetic
bottlenecksduringdomesticationorduringfoundingeventsas
cropsmovedawayfromtheircentersoforiginmayhave
furtheralteredgenepools.Todate,afewhundredgenesand
locihavebeenidentifiedbyclassicalgeneticandassociation
mappingastargetsofdomesticationandpostdomestication
divergence.However,onlyafewofthesehavebeen
characterized,andforevenfeweristheroleofthewild-type
alleleinnaturalpopulationsunderstood.Afterdomestication,
onlyfavorablehaplotypesareretainedaroundselectedgenes,
whichcreatesageneticvalleywithextremelylowgenetic
diversity.These“selectivesweeps”canallowmildly
deleteriousallelestocometofixationandmaycreateagenetic
loadinthecultivatedgenepool.

18. LOSS OF GENETIC DIVERSITY
ThetermbiodiversitywascoinedbyWalterandRosen(1985)
andistheabbreviatedwordforBiologicalDiversity.Life
originatedonearthalmostfourbillionyearsagoandnature
tookmorethan1billionyeartodevelopthiswideandcomplex
spectrumoflifeonearth.Scientistsbelievethatthetotal
numberofspeciesonearthisinbetween10-80million(Wilson
1988)ofwhich1.4millionspecieshavebeenenlistedsofar.
i)Biodiversityisthevarietyoflifeinallitsforms,levelsand
combinations.Itincludesspeciesdiversity,geneticdiversity
andecosystemdiversity(InternationalUnionforConservation
ofNatureandNaturalResources—IUCN,UnitedNations
EnvironmentProgramme—UNEPandWorldWildlifeFund—
WWF1991).

19. BIODIVERSITY-DEFINITIONS
ii)UnitedNationsEarthSummitinRiodeJaneirodefined
biodiversityas–Thevariabilityamonglivingorganismsfrom
allsources,includingterrestrial,marineandotheraquatic
ecosystemsandtheecologicalcomplexesofwhichtheyare
part.Thisincludesdiversitywithinspecies,betweenspecies
andofecosystems.
(iii)AccordingtoU.S.CongressionalBiodiversityAct–
BiologicalDiversityisthevarietyandvariabilityamongliving
organismsandtheecologicalcomplexesinwhichtheyoccur
andencompasesecosystemdiversity,speciesdiversityand
geneticdiversity.iv)Inthesimplestterms,biologicaldiversity
isthevarietyoflifeanditsprocessesanditincludesthevariety
oflivingorganisms,thegeneticdifferencesamongthemand
thecommunitiesandecosystemsinwhichtheyoccur.

20. PLANT BIODIVERSITY

21. TYPES OF BIODIVERSITY
Biodiversityisusuallystudiedatthreedifferentlevels—Species
diversity,GeneticdiversityandEcosystemdiversity.Itactuallyrefers
tospeciesrichness,intermsofnumberofspeciesinasiteorhabitat.
Globaldiversityistypicallyrepresentedintermsoftotalnumberof
speciesofdifferenttaxonomicgroups.Asmentionedbefore,an
estimated1.4millionspecieshavebeenidentifiedtodate.Species
diversity,again,isstudiedatthreelevels:alphadiversity(numberof
speciescoexistingatasite),betadiversity(differenceinspecies
complementbetweenpatches)andgammadiversity(numberof
speciesinalargearea,e.g.acountry).Thisseriescanfurtherbe
extendedtodeltadiversityforbiomes(biomesareclimaticallyand
geographicallydefinedareasofecologicallysimilarclimatic
conditionssuchascommunitiesofplants,animalsandsoilorganisms
andareoftenreferredtoasecosystems)andomegadiversityforthe
entirebiosphere.

22. SPECIES DIVERSITY

23. CAUSES OF LOSS OF GENETIC DIVERSITY
Alterationandlossofthehabitats:Thetransformationofthe
naturalareasdeterminesnotonlythelossofthevegetable
species,butalsoadecreaseintheanimalspeciesassociatedto
them.
Introductionofexoticspeciesandgeneticallymodified
organisms:Speciesoriginatingfromaparticulararea,
introducedintonewnaturalenvironmentscanleadtodifferent
formsofimbalanceintheecologicalequilibrium.Referto,
“Introductionofexoticspeciesandgeneticallymodified
organisms”.
Pollution:Humanactivityinfluencesthenaturalenvironment
producingnegative,directorindirect,effectsthataltertheflow
ofenergy,thechemicalandphysicalconstitutionofthe
environmentandabundanceofthespecies.

24. CAUSES OF LOSS OF GENETIC DIVERSITY
Climatechange:Forexample,heatingoftheEarth’s
surfaceaffectsbiodiversitybecauseitendangersall
thespeciesthatadaptedtothecoldduetothelatitude(the
Polarspecies)orthealtitude(mountainspecies).
Overexploitationofresources:Whentheactivitiesconnected
withcapturingandharvesting(hunting,fishing,farming)a
renewablenaturalresourceinaparticularareaisexcessively
intense,theresourceitselfmaybecomeexhausted,asfor
example,isthecaseofsardines,herrings,cod,tunaandmany
otherspeciesthatmancaptureswithoutleavingenoughtime
fortheorganismstoreproduce.
Theintroductionofinvasivespeciesisthetremendous
threattobiodiversitycrisis.Thespecies,whichisnot
nativetotheecosystem,arrivesorisintroducedmostly
viahumansinthe

25. CAUSES OF LOSS OF GENETIC DIVERSITY
newecosystemandstarttopullulateiscalledasinvasivespecies.
Suchspeciesaredetrimentalastheyeffecttheecosystem
disproportionatelycomparedtoanyotherspecies.Mostofthenew
speciesintroducedintheecosystemdonotbecomeinvasive,butfew
ofthemturnintoinvasivespeciesandadverselyaffectthe
ecosystem.
Naturalcatastrophes,forinstancevolcanoes,wildfires,floods,
hurricanes,draughts,epidemics,tsunamisetc.causeaheavylossof
biodiversity.InhumidtropicalareassuchascentralAfrica,eastern
andnorthernAustralia,someareasofSouthAmericafloodsare
common.Thetropicalareasharborlotofvegetationandvastnumber
ofanimalssurviveinthevegetation.Duetoflooding,largeamount
ofnutrientsfromthesoilgetswashedaway.Droughttooledtodry
soilanddeclineinthelevelofwatertable[29].Inthissituation,both
animalsaswellasplantssuffer.

26. EVOLUTION OF NEW CROPS/VARITIES
Domesticationisagoodmodelforthestudyofevolutionary
processesbecauseoftherecentevolutionofcropspecies
(<12,000yearsago),thekeyroleofselectionintheirorigins,
andgoodarchaeologicalandhistoricaldataontheirspreadand
diversification.Recentstudies,suchasquantitativetraitlocus
mapping,genome-wideassociationstudiesandwhole-genome
resequencingstudies,haveidentifiedgenesthatareassociated
withtheinitialdomesticationandsubsequentdiversificationof
crops.Together,thesestudiesrevealthefunctionsofgenesthat
areinvolvedintheevolutionofcropsthatareunder
domestication,thetypesofmutationsthatoccurduringthis
processandtheparallelismofmutationsthatoccurinthesame
pathwaysandproteins,aswellastheselectiveforcesthatare
actingonthesemutationsandthatareassociatedwith
geographicaladaptationofcropspecies.

27. EVOLUTION OF CROPS
Adivergentprocesswhichincreasesgeneticdiversityandleads
tochangeinallelicfrequenciesinapopulationisknownas
evolution.Inotherwords,aprocesswhichleadstosignificant
deviationinthecharacteristicfeaturesofexistingindividualsas
comparedtotheirpre-existingindividualsistermedevolution.
Evolution–Natural&Manmade.Incaseofnaturalevolution,
naturalselectionoperates,whileinman-madeevolutionhuman
selectionoperates.Thus,bothnaturalandhumanselections
playsignificantroleintheprocessofevolution.Plantbreeding
isconsideredascurrentphaseofcropevolution.Changes
whicharebroughtoutasaresultofevolutionaremeasuredin
termsofmorphological,anatomical,embryological,
physiological,biochemicalandgeneticmodificationsinthe
presentformsofindividualsascomparedwiththeirpastforms.

28. FACTORS OF EVOLUTION
(1)Polyploidy,
(2)Introgression,and
(3)Mutationshaveplayedsignificantroleintheevolutionof
variouscropplants.
Thesethreefactorsaidintheprocessofevolutionbywayof
inducingadditionalgeneticvariability,whichisabasic
requirementforselectiontooperate.
Polyploidy:
Polyploidyreferstonumericalchangeinthegenome(Abasic
setofchromosomes)-Autopolyploidy&Allopolyploids.
Allopolyploidbearsstrongsignificanceasperasthespeciation
isconcernedasitresultsfromdoublingofchromosomesof
interspecifichybrid.

29. AUTOPOLYPLOIDS
Thisisalsoknownassimplepolyploidyorsinglespecies
polyploidy,becausetheincreaseinchromosomenumber
relatestothesamespecies.Thistypeofpolyploidycanoccur
innatureaswellascanbeinducedbycolchicinetreatment.
Increaseinchromosomefromdiploidtotetraploidstateleads
toincreaseinvigourandsizeofflowersandfruitsoverdiploid
forms.However,polyploidplantsexhibitslowgrowthrateand
reducedfertilityduetochromosomalimbalance.
Autopolyploidyhasbeenusedincropslikebanana,apples,
sugarbeet,watermelon,potato,oranges,tulips,etc.The
commercialbananaisautotriploid(3n),whichhasseedlessand
largerfruitsthandiploidforms.Somevarietiesofapplesin
USAaretriploids,whicharepropagatedasexuallyby
buddingandgrafting.Triploidvarietiesofsugarbeet
havehighersugarcontentthandiploidsTriploid
watermelons.

30. AUTOPOLYPLOIDS

31. INTROGRESSION
Incorporationofgeneofonespeciesintothegenetic
backgroundofanotherspeciesbymeansofinterspecific
hybridizationandbackcrossingisknownasintrogression
(Anderson,1949).Theinterspecifichybridbackcrossesin
naturewithoneoftheparentalspecies.
Asaresultofintrogression,genesfromtwodivergentspecies
arecombined.Atruebreedingrecombinantformfavoredby
naturalselectionmaygiverisetoanewspecies.Introgressive
hybridizationbetweenprimitivemaizeandwildgrass
Tripsacumisconsideredtoberesponsiblefortheevolutionof
modernformsofmaize.

32. INTERSPECIFIC HYBRIDIZATION

33. MUTATIONS
Mutationsareimportantsourcesofcreatingvariabilityina
geneticpopulation.Mutationscanoccurinnatureaswellas
canbeinducedbytheuseofphysicalorchemicalmutagenic
agents.Inhexaploidwheat,anaturalmutationisresponsible
forhomologouspairing.Spontaneousmutationshaveplayed
significantroleintheevolutionofcropplants.Spontaneous
mutationscanbeusedeitherasacultivarorasaparentinthe
hybridizationprogramme.Inducedmutationshaveplayedkey
roleinimprovingyield,quality,earliness,adaptation,and
diseaseandinsectresistanceinvariouscropplants.
Thebreadwheatishexaploid,combiningdiploidchromosome
complementsfromthreedifferentspecies.Innature,hexaploid
breadwheatbehavesasdiploid[n=21and2n=42].Ithas
beenfoundthathexaploidwheathasacquiredthispropertyof
diploidpairingfromamutationonchromosomenumber5B,
whichinhibitspairingbetweenhomologouschromosomes
(chromosomesofdifferentgenomes).

34. CHROMOSOME MUTATION

35. DIFFERENT TYPES OF CROP EVOLUTION
Thegeneticevolutionofsomeimportantfieldcropssuchas
wheat,cotton,tobacco,Brassica,potato,maizeandriceis
brieflydescribedbelow:
Thetetraploidspeciesdevelopedasanamphidiploidsbetween
twodiploidspecies,andhexaploidspeciesoriginatedfroma
crossbetweentetraploidanddiploidspecies.Itisbelievedthat
tetraploidspeciesTriticumturgidumevolvedasan
amphidiploidsbetweenTriticummonococcum(AA)andan
unknownspecies(nowprobablyextinct)withBBgenome.The
hexaploidbreadwheatoriginatedasanamphidiploidsbetween
Triticumturgidum(AABB)andT.tauschii(DD).Theoverall
processcanberepresentedasfollows.

36. WHEAT EVOLUTION

37. DIFFERENT SPECIES OF TRITICUM

38. ALLOPOLYPLOIDS
Thisisalsoknownashybridpolyploidyorbispeciesor
multispeciespolyploidydependinguponthespeciesinvolved.
Suchpolyploidyisobtainedbydoublingofchromosome
numberbycolchicinestreatment.Allopolyploidhasbeenmore
instrumentalinevolutionofcropplants,because50%ofthe
cropplantsareallopolyploids.
Hybridpolyploidyhasplayedsignificantroleintheevolution
ofcropslikewheat,tobacco,cotton,Brassica,oat,etc.
Examplesofartificiallyproducedallopolyploidsinclude
triticale,strawberryandloganberry.
Triticaleisaman-madenewcereal(betweenwheatandrye),
whichcombineshighyieldofwheatanddiseaseanddrought
resistanceofrye.

39. GERMPLASM & IMPORTANCE
Germplasmcontainstheinformationforaspecies'genetic
makeup,avaluablenaturalresourceofplantdiversity.
Agriculturebenefitsfromuniformityamongcropplantswithin
avariety,whichensuresconsistentyieldsandmake
managementeasier.Germplasminabroadwaycanbe
definedasthehereditarymateriali.e.totalcontentof
geneswhichisinheritedbytheoffspringsthrough
germcells.Germplasmservesastherawmaterialfor
thebreedertoproducevariouscrops.Therefore,
conservationofgermplasmhasimportanceinall
breedingprogrammes.Inpreviousdays,humans
gainedtheknowledgeabouttheuseofplantsforfood,
shelterandmanymore,thustheystartedsaving
selectedseedsorvegetativepropagulesfromone
seasontothenextone.Thepossibilityoflifeonearth
ismainlyduetotheplantsasitis

40. GERMPLASM & IMPORTANCE
thecrucialcomponentoftheecosystem,thusitspreservationis
ourresponsibilityforthecontinuationoflife.Inotherwords,it
mayberegardedastheconventionalgermplasmpreservation
andmanagement,whichishighlypreciousinbreeding
programmes.Themainobjectiveofgermplasmconservationis
topreservethegeneticdiversityofselectedplantsorgenetic
stockforitsutilizationatanytimeinfuture.
Inrecentyears,theprimitiveandconventionallyused
agriculturalplantsarebeingreplacedbymanynewplant
specieswithdesiredandimprovedcharacteristics.Itisvery
crucialtoconservetheendangeredplantsotherwisesomeof
theimportantgenetictraitspossessedbytheprimitiveplants
maybelost.Ithasbeenestimatedthatupto100,000plants,
depictingmorethanonethirdofalltheworld’splantspecies,
arecurrentlythreatenedorfaceextinctioninthewild.

41. PROSPECTS OF GERMPLASM
Aspreviouslystated,Geneticresourceistreatedas
Germplasmandthegermplasmareusedextensivelyfor
thefollowingattributes:1.Varietiesusedincultivation-
Therearegoodsourcesofgenesforqualityyield
becausetheycanbeintroducedintonewgeographical
regionforthecultivationtoaddeconomic
gain,2.Breedinglines-Inthedifferentbreeding
programmes,thedifferentnarrowgeneticbasewith
valuablegenecombinationsareusedandtheycanbe
usedforthewidescalebreedingexercises.3.Forspecial
geneticstocks-Theselinesarecarryingchromosomal
aberrations,genemutationsetcandthesewillbesetof
monosomicorbisomiclinestobeinducedartificially,
Wildrelativesandforms-Thesearevaluablesourceof
genesfordevelopmentofGMPthroughgenetic
engineeringprogrammes.

42. THANK YOU FOR YOUR JOURNEY

43. ACKNOWLEDGMENTS
1.Forimages:Google
2.Differentwebpagesorfreeresources
Differentarticlesfromdifferentwebsites
EconomicBotany-BhabanandaBaruah,
EconomicBotany-S.Chand&company
Disclaimer:ThisPPThasbeenmadeanddesignedfor
purelyacademicpurposewithoutanyfinancialgainand
canbeaccessfreelybytheacademicfraternity.