dc.contributor.advisor | Ford, Rebecca | |
dc.contributor.author | Zhou, Ziwei | |
dc.date.accessioned | 2018-10-31T06:41:12Z | |
dc.date.available | 2018-10-31T06:41:12Z | |
dc.date.issued | 2018-06 | |
dc.identifier.doi | 10.25904/1912/1750 | |
dc.identifier.uri | http://hdl.handle.net/10072/381001 | |
dc.description.abstract | Chickpea (Cicer arietinum L.) is an important cool season food legume, playing a
significant role in global food security. However, the production of chickpea is
severely constrained by foliar Ascochyta blight disease caused by the fungus
Ascochyta rabiei (syn. Phoma rabiei). The disease results in substantial yield losses
annually and has become a primary biotic constraint to production in Australia.
Several disease management options have been developed to reduce or control the
pathogen, including host plant resistance. However, for host resistance to be effective,
the plant must quickly recognise the pathogen and instigate initial defence
mechanisms at the point of contact. Previous research has shown that the most
resistant host genotypes are able to recognise the pathogen the fastest.
Resistance Gene Analogues (RGAs) are key factors in the recognition of plant
pathogens and the signaling of inducible defences. They comprise a large gene family
with conserved domains and structural features; classified as either nucleotide binding
site leucine rich repeat (NBS-LRR) or transmembrane leucine rich repeat (TM-LRR)
groups. In chickpea, they are reported to recognise A. rabiei with varying knowledge
of their identities and putative functions.
In this study, a suit of RGA loci were chosen from both published literature and from
homologous sequences within the NCBI database for further investigation. All RGA
candidates were members of the NBS-LRR family group. Following their validation
in the chickpea genome through traditional PCR, and qPCR primer optimization, 10
of the target RGA were selected for differential expression analysis in response to A.
rabiei. This was performed in a set of four chickpea genotypes including two resistant
cultivars (ICC 3996 and PBA Seamer), one moderately resistant cultivar (PBA
HatTrick) and one susceptible cultivar (Kyabra). Expression of each locus was
assessed via qPCR at 2, 6, and 24 hours after A. rabiei infection with a previously
characterised highly aggressive isolate. As a result, all loci were differentially
transcribed in response to pathogen infection in at least one genotype and at least one time point after inoculation. Among these, transcription of RGA 8, RGA 10, RGA 21
and RGA 23 was significantly and consistently increased in the resistant genotype
ICC 3996 immediately following inoculation. Further bioinformatics in-silico
analyses of these four RGA indicated they all function through ADP binding, in
different parts of pathogen recognition pathway. These represent clear targets for
future functional validation and potential for selective resistance breeding and/or for
introgression into elite cultivars that are quickly able to recognise and respond to A. rabiei. | |
dc.language | English | |
dc.language.iso | en | |
dc.publisher | Griffith University | |
dc.publisher.place | Brisbane | |
dc.subject.keywords | Ascochyta rabiei | |
dc.subject.keywords | Chickpea | |
dc.subject.keywords | Disease management options | |
dc.subject.keywords | Resistance gene analogues | |
dc.subject.keywords | Loci | |
dc.title | Determination of the key resistance gene analogues involved in Ascochyta rabiei recognition in Chickpea | |
dc.type | Griffith thesis | |
gro.faculty | Science, Environment, Engineering and Technology | |
gro.rights.copyright | The author owns the copyright in this thesis, unless stated otherwise. | |
gro.hasfulltext | Full Text | |
dc.contributor.otheradvisor | Love, Christopher | |
gro.thesis.degreelevel | Thesis (Masters) | |
gro.thesis.degreeprogram | Master of Science (MSc) | |
gro.department | School of Environment and Sc | |
gro.griffith.author | Zhou, Ziwei | |