Year: 2009
Type: dissertation
Abstract: Basal resistance utilises receptors which detect non-race specific elicitors known as pathogen associated molecular patterns (PAMPs).While not commonly resulting in a hypersensitive response, it shares some downstream signalling and effector components with R gene-mediated resistance.To better understand the genetic basis of basal resistance, a virulent Pseudomonas strain tagged with a constitutively expressed LuxCDABE operon was utilised to create a high throughput quantitative bacterial growth assay.Measuring bacterial photon emission from leaf tissue in a selection of ecotypes showed a wide range of bacterial growth, implying substantial natural genetic variation in basal resistance.Several independent RIL populations were trialled and combined with other data for QTL analysis to define the chromosomal locations responsible for resistance variation.Within markers flanking each significant QTL peak, there are numerous candidate genes.Cross-referencing candidates against annotation information indicating involvement in biotic stress, respiratory burst or induction by flg22 treatment, creates a significantly refined list.A LysM receptor-like kinase family appears in the majority of QTL locations across independent populations at a statistically higher rate and is therefore implicated in pathogen recognition.Replication using other Pseudomonas bacterial strains produces similar LysM gene associations, implicating broad perception mechanisms.Transcriptional, phylogenetic and functional characterisation found LysM genes consistent with characteristics of known disease resistance components.A LysM gene sequence comparison between genotypes with substantial variation of basal resistance found significant polymorphisms, however, a direct relationship between these differences and trait data could not be conclusively shown. PseudomonasAvrPtoB kinase suppression can increase susceptibility in different genotypes but does not directly correlate with QTLs, LysM gene placement and suppression pattern.Several T-DNA knockout lines showed a moderate increase (40-60%) in susceptibility for lines targeting specific LysM genes compared with Col-0 controls.Not all lines show this pattern but most tested lines show effects on basal resistance after gene knockout, directly implicating several LysM genes as components in basal resistance.
Author: Andrew Glyn Staphnill
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W1504454119