scholarly journals Transcriptome Analysis of Eucalyptus grandis Implicates Brassinosteroid Signaling in Defense Against Myrtle Rust (Austropuccinia psidii)

2021 ◽  
Vol 4 ◽  
Author(s):  
Shae Swanepoel ◽  
Caryn N. Oates ◽  
Louise S. Shuey ◽  
Geoff S. Pegg ◽  
Sanushka Naidoo
Keyword(s):  
Disease Resistance ◽  
Rna Sequencing ◽  
Plant Disease Resistance ◽  
Rust Fungus ◽  
Eucalyptus Grandis ◽  
Post Inoculation ◽  
Puccinia Psidii ◽  
Myrtle Rust ◽  
Brassinosteroid Signaling ◽  
Austropuccinia Psidii

Eucalyptus grandis, in its native Australian range, varies in resistance to Austropuccinia psidii (syn. Puccinia psidii). The biotrophic rust fungus, A. psidii is the causal agent of myrtle rust and poses a serious threat to Australian biodiversity. The pathogen produces yellow pustules of urediniospores on young leaves and shoots, resulting in shoot tip dieback, stunted growth, and death. Dissecting the underlying mechanisms of resistance against this pathogen will contribute to improved breeding and control strategies to mitigate its devastating effects. The aim of this study was to determine the molecular dialogue between E. grandis and A. psidii, using an RNA-sequencing approach. Resistant and susceptible E. grandis seedlings grown from seed collected across its natural range were inoculated with the pandemic biotype of A. psidii. The leaf tissue was harvested at 12-h post inoculation (hpi), 1-day post inoculation (dpi), 2-dpi and 5-dpi and subjected to RNA-sequencing using Illumina 50 bp PE reads to a depth of 40 million reads per sample. Differential gene expression and gene ontology enrichment indicated that the resistant seedlings showed controlled, coordinated responses with a hypersensitive response, while the susceptible seedlings showed no systemic response against myrtle rust. Brassinosteroid signaling was apparent as an enriched term in the resistant interaction at 2-dpi, suggesting an important role of this phytohormone in defense against the pathogen. Brassinosteroid mediated signaling genes were also among the candidate genes within two major disease resistance loci (Puccinia psidii resistance), Ppr3 and Ppr5. While brassinosteroids have been tagged as positive regulators in other plant disease resistance interactions, this is the first report in the Eucalyptus – Austropuccinia psidii interaction. Furthermore, several putative resistance genes, underlying known resistance loci and implicated in the interaction have been identified and highlighted for future functional studies. This study provided further insights into the molecular interactions between E. grandis and A. psidii, contributing to our understanding of this pathosystem.

scholarly journals Evaluating the efficacy of potential fungicide-adjuvant combinations for control of myrtle rust in New Zealand

2021 ◽  
Author(s):  
Kwasi Adusei-Fosu ◽  
Carol A. Rolando ◽  
Brian Richardson ◽  
Rebecca van Leeuwen ◽  
Robyn Gaskin ◽  
...  
Keyword(s):  
New Zealand ◽  
Leaf Surface ◽  
Post Inoculation ◽  
Myrtle Rust ◽  
Good Surface ◽  
Spray Inoculation ◽  
Leaf Surfaces ◽  
Austropuccinia Psidii ◽  
Tea Extract

AbstractMyrtle rust is a serious fungal disease caused by Austropuccinia psidii affecting a number of Myrtaceae species in New Zealand and elsewhere. Control with fungicides or biologicals provides a mechanism to reduce the build-up of inoculum in the short-term while other strategies are being developed or deployed for long-term management. This study evaluated the efficacy of fungicides for control of myrtle rust under controlled conditions and identified adjuvants that would promote spreading of fungicidal active ingredients across the leaf surface. The spread of fungicide on detached M. excelsa leaves was assessed by applying three different adjuvants in combination with seven fungicides. Subsequently, M. excelsa plants were treated with three fungicides/mixes, (azoxystrobin + epoxiconazole, triademinol or a natural tea-extract) at a single rate followed by inoculation with A. psidii urediniospores on day 0, 7, 14 or 21 days after spraying. The response to infection in M. excelsa plants based on different inoculation timings at days 0, 7 and 21 significantly differed among fungicide treatments. The fungicide azoxystrobin + epoxiconazole was the most effective with infections significantly lower on the adaxial leaf surface than abaxial, despite good surface coverage of fungicide being achieved on both leaf surfaces. There were significant differences among fungicides based on the proportion of infected leaves on M. excelsa plants. Day 21 post-spray inoculation indicated a significant interaction between inoculation time and fungicide on leaf disease ratings. However, this was not the case at either 28 or 35 days post-inoculation. This research contributes to fungicide options for myrtle rust control in New Zealand.

Genome-wide association study of myrtle rust (Austropuccinia psidii) resistance in Eucalyptus obliqua (subgenus Eucalyptus)

2021 ◽  
Vol 17 (3) ◽  
Author(s):  
Wilson Thau Lym Yong ◽  
Peter K. Ades ◽  
Fatima Akter Runa ◽  
Gerd Bossinger ◽  
Karanjeet S. Sandhu ◽  
...  
Keyword(s):  
Association Study ◽  
Genome Wide Association Study ◽  
Genome Wide Association ◽  
Myrtle Rust ◽  
Genome Wide ◽  
Austropuccinia Psidii

scholarly journals A family of pathogen-induced cysteine-rich transmembrane proteins is involved in plant disease resistance

Planta ◽  
2021 ◽  
Vol 253 (5) ◽  
Author(s):  
Marciel Pereira Mendes ◽  
Richard Hickman ◽  
Marcel C. Van Verk ◽  
Nicole M. Nieuwendijk ◽  
Anja Reinstädler ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plasma Membrane ◽  
Disease Resistance ◽  
Plant Disease Resistance ◽  
Transmembrane Proteins ◽  
Series Data ◽  
Immune Gene ◽  
Biological Processes ◽  
Hypocotyl Growth ◽  
Enhanced Resistance

Abstract Main conclusion Overexpression of pathogen-induced cysteine-rich transmembrane proteins (PCMs) in Arabidopsis thaliana enhances resistance against biotrophic pathogens and stimulates hypocotyl growth, suggesting a potential role for PCMs in connecting both biological processes. Abstract Plants possess a sophisticated immune system to protect themselves against pathogen attack. The defense hormone salicylic acid (SA) is an important player in the plant immune gene regulatory network. Using RNA-seq time series data of Arabidopsis thaliana leaves treated with SA, we identified a largely uncharacterized SA-responsive gene family of eight members that are all activated in response to various pathogens or their immune elicitors and encode small proteins with cysteine-rich transmembrane domains. Based on their nucleotide similarity and chromosomal position, the designated Pathogen-induced Cysteine-rich transMembrane protein (PCM) genes were subdivided into three subgroups consisting of PCM1-3 (subgroup I), PCM4-6 (subgroup II), and PCM7-8 (subgroup III). Of the PCM genes, only PCM4 (also known as PCC1) has previously been implicated in plant immunity. Transient expression assays in Nicotiana benthamiana indicated that most PCM proteins localize to the plasma membrane. Ectopic overexpression of the PCMs in Arabidopsis thaliana resulted in all eight cases in enhanced resistance against the biotrophic oomycete pathogen Hyaloperonospora arabidopsidis Noco2. Additionally, overexpression of PCM subgroup I genes conferred enhanced resistance to the hemi-biotrophic bacterial pathogen Pseudomonas syringae pv. tomato DC3000. The PCM-overexpression lines were found to be also affected in the expression of genes related to light signaling and development, and accordingly, PCM-overexpressing seedlings displayed elongated hypocotyl growth. These results point to a function of PCMs in both disease resistance and photomorphogenesis, connecting both biological processes, possibly via effects on membrane structure or activity of interacting proteins at the plasma membrane.

The Leucine-Rich Repeat Domain Can Determine Effective Interaction Between RPS2 and Other Host Factors in Arabidopsis RPS2-Mediated Disease Resistance

Genetics ◽  
2001 ◽  
Vol 158 (1) ◽  
pp. 439-450 ◽  
Author(s):  
Diya Banerjee ◽  
Xiaochun Zhang ◽  
Andrew F Bent
Keyword(s):  
Disease Resistance ◽  
Pseudomonas Syringae ◽  
Plant Disease Resistance ◽  
Effective Interaction ◽  
Molecular Genetic ◽  
Defense Responses ◽  
Host Factors ◽  
Leucine Rich Repeat ◽  
Domain Swap ◽  
Allele Specific

Abstract Like many other plant disease resistance genes, Arabidopsis thaliana RPS2 encodes a product with nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domains. This study explored the hypothesized interaction of RPS2 with other host factors that may be required for perception of Pseudomonas syringae pathogens that express avrRpt2 and/or for the subsequent induction of plant defense responses. Crosses between Arabidopsis ecotypes Col-0 (resistant) and Po-1 (susceptible) revealed segregation of more than one gene that controls resistance to P. syringae that express avrRpt2. Many F2 and F3 progeny exhibited intermediate resistance phenotypes. In addition to RPS2, at least one additional genetic interval associated with this defense response was identified and mapped using quantitative genetic methods. Further genetic and molecular genetic complementation experiments with cloned RPS2 alleles revealed that the Po-1 allele of RPS2 can function in a Col-0 genetic background, but not in a Po-1 background. The other resistance-determining genes of Po-1 can function, however, as they successfully conferred resistance in combination with the Col-0 allele of RPS2. Domain-swap experiments revealed that in RPS2, a polymorphism at six amino acids in the LRR region is responsible for this allele-specific ability to function with other host factors.

Role of transporters in plant disease resistance

2021 ◽  
Vol 171 (4) ◽  
pp. 849-867
Author(s):  
Basavantraya N. Devanna ◽  
Rajdeep Jaswal ◽  
Pankaj Kumar Singh ◽  
Ritu Kapoor ◽  
Priyanka Jain ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Plant Disease Resistance ◽  
Plant Disease
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