http://www.csiro.au/Organisation-Structure/Divisions/Plant-Industry/LarsKamphuis.aspx Sap-suckinginsects, such as aphids, are majorpests in agriculture causingdirectfeedingdamage andtransmittingover50%ofallplantviruses. The group has builtup an excellentsystemto studysap-suckinginsectpests involvingthe modellegumeMedicago truncatula and various aphid species includingthe modelaphid, pea aphid. The combination ofpowerfulgenetic and genomic tools/resources on both the plantandaphid sides ofthe interaction enable cuttingedge research and its’application to agriculture. Two potentialprojects in this area are: 1a)Characterisationofloss ofresistance to aphidsmutantin the modellegume Medicago truncatula:The legumeMedicago truncatula cultivarJesterhas resistance to three aphid species. A mutagenised Jesterplanthas been identified thathas lostresistance to allthree aphids. Resistance to aphids occurs throughrecognition byindependentplants resistance genes foreach aphid, which in turn triggers downstreamdefense responses in the plant. The identified mutantis compromised in resistance to three differentaphidspecies makingthis a veryinterestingmutant, with a mutation in a gene thatis essentialin the downstreamsignallingcascade to mounta successfuldefense response to allthree aphid species. Detailedcharacterisation ofthis mutantand the behaviourofthe aphids includingfeedingbehaviourand aphidsettlingin choice tests and aphid performancewhengiven no choice ofplantwould shed morelighton theresistance mechanisms thathave been lostin this mutantplant. The characterisation ofclassicaldefensepathways in this mutantwillalso shed lighton which majordefense signallingpathwaysmightbe affectedin this mutant, resultingin the loss ofresistance to allthree aphid species. The proposed research wouldexpose the studentto range ofdisciplines includingphysiology,molecularbiology,biochemistryand basicbioinformatics, makingthis an interestingand excitingproject. 1b)CharacterisationofRgene mediateddefences following aphid attack:Resistance to bluegreenaphid is controlled bya singledominantgenetermed AKR(Acyrthosiphon kondoiresistance). Apairofnear-isogenic lines has been generated which are eitherresistant(havingAKR)orsusceptible (lackingAKR)to bluegreen aphid. Potentialprojects usingtranscriptomics and/ormetabolomicsare available to identifykeyregulators and defence pathways recruited bythe AKR resistance gene followingrecognition oftheaphid. The proposed research would expose the studentto range ofdisciplines includingmolecularbiology,biochemistry,metabolomics,proteomics and basic bioinformatics, makingthis an interestingand excitingproject.
2. Resistance to fungalpathogensWinthrop Professor KaramSingh
http://www.csiro.au/Organisation-Structure/Divisions/Plant-Industry/LouiseThatcher.aspx Fungaldiseases are majorproblems forAustralian agriculture. One such importantpathogen,R. solani,causes substantiallosses to wheat, barley, canola and variouslegumes in Australia. Internationallyitis thesecond mostimportantdisease problemforthe world’s largeststaple food, rice. Anotherdevastatingfungalpathogen is Fusarium oxysporum, causalagentofFusariumvascularwiltand able to infectover100 plantspecies includinggrainlegumes(e.g.chickpea, lupin)and oilseed crops (e.g. canola, cotton).
Internationally,Fusariumwiltdisease can cause losses of10-100%in chickpea. Australia is currentlyfreefromisolates capable ofinfectingourmajorgrainlegumes(chickpea, lupin and lentil)however, thepathogen presents as a highbiosecuritythreatto these industries. The group uses powerfulgenomic andbioinformatic approaches on both the plantand pathogen side to unravelthe mechanismsunderlyingresistance orsusceptibility. 2a)Characterisehostgenes linkedto fungalresistance using molecular and reverse geneticapproaches:The group has identified specific transcription factors and regulatorygenes in bothArabidopsis and M. truncatula thatare keymediators ofplantdefence responses to somefungalpathogens.Potentialprojects include functionalcharacterisation throughtransgenic(knockoutoroverexpression)ormutantlines, and the identification oftargetgenes and partnerproteins usingmolecularand genomicapproaches. The identification ofregulatorysequences thatallowthe specific expression ofthe transcriptionfactors in various plants is also a keycomponentofproducingplants with enhanced disease resistance. 2b)Identificationofeffectors/pathogenicity genes fromR. solanior F.oxysporumgenomes requiredfor virulence ona planthost:Pathogensemploya sophisticated systemofproteins, called effectors, tointeractwith hostproteins and manipulate the plantinto susceptibility. Identification ofthese effectors canrevealthe planttargets which mayin turn be modified to conferresistance to the pathogen. The group hasrecentlysequenced and assembledgenomes forR. solaniand F.oxysporum. Usinga combination ofpowerfulgeneticresources, bioinformatics and molecularbiology, putative pathogenicityeffectors can beidentified and theirfunction in hostmanipulation investigated.
Novelregulators ofbiotic and abiotic stress induced responses in plants.
http://www.csiro.au/Organisation-Structure/Divisions/Plant-Industry/LouiseThatcher.aspx The protection ofcells fromabiotic orbiotic-induced stress is criticalforan organism’ssurvivaland a groupofubiquitous enzymes centralto this protection are the detoxification familyofglutathione S-transferases(GSTs). The research group ofWinthrop ProfessorSingh conducted a genetic screen in the modelplantArabidopsis thaliana formutantswith altered expression ofthe earlystress-responsivemarkergeneGlutathione S-Transferase Phi8 (AtGSTF8).Severalnovelmutants isolated fromthis screen conferalteredresponses to biotic and/orabiotic stress includingincreased thermo-tolerance and resistance to one ormorefungalpathogens and insectpests.