Role of enzymes in pathogenesis

Explained in detail about role of enzymes in plant disease and their functions in hots plants with examples will be very easy to understand

1. Role of enzymes in pathogenesis
N. H. SHANKAR REDDY
2
nd
, Ph.D., Plant Pathology
Annamalai University

2. •Enzymes–Enzymesarelargeproteinmolecules(2-100mµ
indiameter)whichactasacatalysttobringaspecific
chemicalreactioninlivingcells(whereitconvertsspecific
setofreactantstospecificproducts)
•Acellcontainsseveralmillionenzymes,whichbelongsto
differentkindsofenzymes.

3. •Enzymessecretedbymicroorganismplayakeyrolein
diseasedevelopment.Thesebreakdownplantsubstances
intosmallermoleculeswhichpathogeneasilyabsorband
utilizeforitsgrowthandenergy.
•Differenttypesofenzymearereproducedbypathogenare

4. Cutinases
•Cutinaseswhichdegradecutin,
isthemaincomponentofthe
cuticle,isknowntoproduceby
manyfungiandbacteria.
•Eg-Puccinia hordei

5. Pectinases
•Degradepecticsubstances
whichischiefcomponentof
middlelamellaofplantcells.
•Eg-Phytophthora, Pythium

6. Cellulases
•Producedbyseveralplant
pathogenicfungi,bacteriaand
nematodes,whichplaysamajor
roleinsoftening
•Eg-Fusarium

7. Hemicellulases
•Which breakdown
hemicelluloses,arecomplex
mixtureofpolysaccharidesand
amajorcomponentofprimary
cellwall
•Eg-Sclerotiniasclerotiorum

8. Ligninases
•Breakdownmostresistant
componenttoenzymatic
degradation,lignin
•Eg-Brownrotfungi,white
rot fungi,Xylaria
polymorpha

9. Proteases
•Which degrade proteins
•Thedegradationofhost
proteinsbyproteolyticenzymes
secretedbypathogensaffects
theorganizationandfunctionof
thehostcell.
•Eg-Helminthosporiumoryzae

10. Amylases
•Whichbreakdownstarch
intoglucoseandutilisedby
thepathogen
•FattyAcidisdirectly
utilizedbythepathogen.
•Eg–Manyfungi,bacteria,
andnematodes

11. Lipases
•Which breakdown lipids
(phospholipids,glycolipids).Several
fungi,bacteria&nematodes.
•Eg-Sclerotiumrolfsii,Botrytis
cinerea