Proteomics reveals pathways linked to septoria canker resistance and susceptibility in Populus trichocarpa

Abstract

A major threat to forest ecosystems and plantation forestry is the introduction of a non-native pathogen. Among non-domesticated populations with relatively high levels of genetic diversity, a measurable range of susceptibility to resistance can be expected. Identifying genetic determinants of resistant and susceptible individuals can inform the development of new strategies to engineer disease resistance. Here we describe pathogen-induced changes in the proteome of Populus trichocarpa stem tissue in response to Sphaerulia musiva (Septoria canker). This hemibiotrophic fungal pathogen causes stem canker disease in susceptible poplar genotypes. Proteomics analyses were performed on stem tissue harvested across 0-, 12-, 24- and 48-h post-inoculation with Septoria from three genotypes including one resistant (BESC-22) and two susceptible [BESC-801; Nisqually-1 (NQ-1)]. In total, 11,897 Populus proteins at FDR <0.01 were identified across all time points and genotypes. Analysis of protein abundances between genotypes revealed that the resistant poplar genotype (BESC-22) mounts a rapid and sustained defense response involving pattern recognition receptors, calcium signaling proteins, SAR inducers, transcriptional regulators, resistance proteins, and proteins involved with the hypersensitive response. One susceptible genotype (BESC-801) had a downregulated and delayed defense response whereas the second susceptible genotype (NQ-1) lacked a distinct pattern. Overall, the proteome-wide and protein-specific trends suggest that responses to the Septoria canker infection are genotype-specific for the naïve host, Populus trichocarpa.

Editing Metabolism, Sex, and Microbiome: How Can We Help Poplar Resist Pathogens?

“…It has higher levels of PTI members, such as PRRs (especially important ones such as PtCERK1), PRR coreceptors (such as BAK1 and SOBIR) and HR trigger-related receptors HRLI4 and HIRP, as well as ABC transporters that release phytoalexins. In contrast, ET and JA signals are more active in susceptible poplar [260]. Similar observations were obtained when comparing the response of susceptible P. deltoides and resistant P. tomentosa to Lonsdalea quercina subsp.…”

“…populi bacteriosis. The expression of genes related to SA signaling (such as PR1s, NPR1s, TGA1,2) was higher in the resistant phenotype, while JA signaling genes showed a more diverse pattern: MYC2s were more actively expressed in the resistant plant, while JAZ1 and COI1s in the susceptible plant [260]. Finally, in a system where the intolerant genotype was P. nigra × P. deltoides and the tolerant ones were P. trichocarpa × P. deltoides hybrids, while the infection agent was M. larici-populina, a rust-causing biotroph, in intolerant plants, the JA pathway was activated at the early stages and SA was inhibited; in contrast, in tolerant plants, JA was inhibited, and the expression of genes associated with the SA response (among which NBS-LRRs, EDS1, NDR1, WRKYs and PRs) was upregulated.…”

“…Interestingly, the results of all these papers are consistent with old ideas about the existence of SA-JA antagonism and contradict the articles we discuss earlier at the end of Section 3.1, whose authors concluded that in poplar, SA-and JA-signaling pathways positively affect each other's activity. This is partly because in the articles supporting antagonism, the evidence was indirect, based on genotype correlation: plants with increased SA signaling activity usually had relatively reduced JA activity, and vice versa [260][261][262][263]. However, these observations may not have a direct causal relationship, whereas in the paper [120], the authors experimentally proved a positive interaction by applying exogenous SA or JA to poplar, which led to an increase in the concentration of JA or SA, respectively.…”

Expression quantitative trait loci mapping identified PtrXB38 as a key hub gene in adventitious root development in Populus

“…Proteomics measurements on plant tissues were conducted with three biological replicates, as previously described (Lenz et al ., 2022). Briefly, samples were frozen, ground, and solubilized in a lysis buffer.…”