Abstract
Sphaerulina musiva, the causal agent of leaf spot and stem canker, is responsible for critical yield loss of hybrid poplar in agroforestry. This research examined quantification of S. musiva in host tissue, and infection of leaf tissue, plus gene expression between resistant and susceptible poplar genotypes. This study reports the first use of a multiplexed hydrolysis probe qPCR assay for faster and accurate quantification of S. musiva in inoculated stems of resistant, moderately resistant and susceptible genotypes of hybrid poplar at three different time points -1 wpi (weeks post-inoculation ), 3 wpi and 7 wpi. This assay detected significant differences in the level of resistance among the different clones at 3 wpi (p < 0.001) and significant differences among isolates at 1 wpi (p < 0.001), that were not detected by visual phenotyping. Histological and biochemical comparisons were made between resistant and susceptible genotypes inoculated with conidia of S. musiva in order to study the mode of leaf infection and defense response of hybrid poplar. Leaf infection was examined at 48 h, 96 h, 1 wpi, 2 wpi and 3 wpi using scanning electron microscopy (SEM) and fluorescent and laser scanning confocal microscopy. Infection process of S. musiva on Populus spp. was further characterized by transforming S. musiva with red fluorescent protein through Agrobacterium tumefaciens. Results indicated that there was no difference in pre-penetration processes, however, differences were observed in post-penetration between resistant and susceptible genotypes. The host response was also studied by examining the accumulation of hydrogen peroxide (H2O2) using fluorescent microscopy after DAB staining, and a significant difference (p < 0.0001) was observed by 2 wpi. The molecular mechanism underlying host-pathogen interaction was elucidated by studying temporal differentially expressed genes of both the interacting organisms, simultaneously, using RNA-seq. Genes involved in cell wall modification, antioxidants, antimicrobial compounds, signaling pathways, ROS production and necrosis were differentially expressed in the host. In the pathogen, genes involved in CWDE, nutrient limitation, antioxidants, secretory proteins and other pathogenicity genes were differentially expressed. The results from this research provide an improved understanding of poplar resistance/susceptibility to S. musiva.
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Claims 10
Claim · model-written summary
Resistance level differed significantly among the poplar clones at 3 weeks post-inoculation.
- Material
- different clonese1
- Interactor
- Sphaerulina musivaSphaerulina musivae0pathogen
- Outcome
- level of resistancee1
PopulusNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sphaerulina musiva, the causal agent of leaf spot and stem canker, is responsible for critical yield loss of hybrid poplar in agroforestry”
e1“significant differences in the level of resistance among the different clones at 3 wpi (p < 0.001)”
Claim · model-written summary
Sphaerulina musiva isolates differed significantly at 1 wpi, a difference that visual phenotyping did not detect.
- Interactor
- Sphaerulina musivaSphaerulina musivae0pathogen
- Outcome
- differences among isolatese1
- Qualifier
- not detected by visual phenotypinge1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sphaerulina musiva, the causal agent of leaf spot and stem canker, is responsible for critical yield loss of hybrid poplar in agroforestry”
e1“significant differences among isolates at 1 wpi (p < 0.001), that were not detected by visual phenotyping”
Claim · model-written summary
A multiplexed hydrolysis probe qPCR assay quantified S. musiva in inoculated hybrid poplar stems faster and more accurately than visual phenotyping.
- Interactor
- S. musivaSphaerulina musivae1pathogen
- Outcome
- quantification of S. musiva in inoculated stemse1
- Comparator
- visual phenotypinge2
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sphaerulina musiva, the causal agent of leaf spot and stem canker, is responsible for critical yield loss of hybrid poplar in agroforestry”
e1“a multiplexed hydrolysis probe qPCR assay for faster and accurate quantification of S. musiva in inoculated stems”
e2“significant differences among isolates at 1 wpi (p < 0.001), that were not detected by visual phenotyping”
Claim · model-written summary
No difference in pre-penetration processes was found between resistant and susceptible poplar genotypes infected by S. musiva.
- Material
- resistant and susceptible genotypese1
- Interactor
- S. musivaSphaerulina musivae0pathogen
- Outcome
- pre-penetration processese1
- Direction
- no differencee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“there was no difference in pre-penetration processes, however, differences were observed in post-penetration between resistant and susceptible genotypes”
Claim · model-written summary
Post-penetration processes differed between resistant and susceptible poplar genotypes infected by S. musiva.
- Material
- resistant and susceptible genotypese1
- Interactor
- S. musivaSphaerulina musivae0pathogen
- Outcome
- post-penetratione1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“there was no difference in pre-penetration processes, however, differences were observed in post-penetration between resistant and susceptible genotypes”
Claim · model-written summary
Hydrogen peroxide accumulation differed significantly between resistant and susceptible hybrid poplar genotypes by 2 wpi.
- Material
- resistant and susceptible genotypese1
- Outcome
- accumulation of hydrogen peroxide (H2O2)e3
- Qualifier
- by 2 wpie2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sphaerulina musiva, the causal agent of leaf spot and stem canker, is responsible for critical yield loss of hybrid poplar in agroforestry”
e1“Histological and biochemical comparisons were made between resistant and susceptible genotypes inoculated with conidia of S. musiva”
e2“a significant difference (p < 0.0001) was observed by 2 wpi”
e3“the accumulation of hydrogen peroxide (H2O2) using fluorescent microscopy after DAB staining”
Claim · model-written summary
Genes involved in cell wall modification, antioxidants and antimicrobial compounds were differentially expressed in the host poplar.
- Outcome
- Genes involved in cell wall modification, antioxidants, antimicrobial compoundse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“Genes involved in cell wall modification, antioxidants, antimicrobial compounds, signaling pathways, ROS production and necrosis were differentially expressed in the host”
Claim · model-written summary
Genes involved in signaling pathways, ROS production and necrosis were differentially expressed in the host poplar.
- Outcome
- signaling pathways, ROS production and necrosise1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“Genes involved in cell wall modification, antioxidants, antimicrobial compounds, signaling pathways, ROS production and necrosis were differentially expressed in the host”
Claim · model-written summary
In the pathogen, genes involved in CWDE, nutrient limitation and antioxidants were differentially expressed during infection of poplar.
- Interactor
- S. musivaSphaerulina musivae0pathogen
- Outcome
- In the pathogen, genes involved in CWDE, nutrient limitation, antioxidantse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“In the pathogen, genes involved in CWDE, nutrient limitation, antioxidants, secretory proteins and other pathogenicity genes were differentially expressed”
Claim · model-written summary
In the pathogen, secretory proteins and other pathogenicity genes were differentially expressed during infection of poplar.
- Interactor
- S. musivaSphaerulina musivae0pathogen
- Outcome
- secretory proteins and other pathogenicity genese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection process of S. musiva on Populus spp.”
e1“In the pathogen, genes involved in CWDE, nutrient limitation, antioxidants, secretory proteins and other pathogenicity genes were differentially expressed”