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The Oomycete plant pathogen,Phytophthora capsici, causes root, crown, and fruit rot of winter squash (Cucurbita moschata) and limits production. SomeC. moschatacultivars develop age-related resistance (ARR), whereby fruit develop resistance toP. capsici14 to 21 days postpollination (DPP) because of thickened exocarp; however, wounding negates ARR. We uncovered the genetic mechanisms of ARR of twoC. moschatacultivars, Chieftain and Dickenson Field, that exhibit ARR at 14 and 21 DPP, respectively, using RNA sequencing. The sequencing was conducted using RNA samples from ‘Chieftain’ and ‘Dickenson Field’ fruit at 7, 10, 14, and 21 DPP. A differential expression and subsequent gene set enrichment analysis revealed an overrepresentation of upregulated genes in functional categories relevant to cell wall structure biosynthesis, cell wall modification/organization, transcription regulation, and metabolic processes. A pathway enrichment analysis detected upregulated genes in cutin, suberin monomer, and phenylpropanoid biosynthetic pathways. A further analysis of the expression profile of genes in those pathways revealed upregulation of genes in monolignol biosynthesis and lignin polymerization in the resistant fruit peel. Our findings suggest a shift in gene expression toward the physical strengthening of the cell wall associated with ARR toP. capsici. These findings provide candidate genes for developingCucurbitacultivars with resistance toP. capsiciand improve fruit rot management inCucurbitaspecies.
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Uncovering genetic and metabolite markers associated with resistance against anthracnose fruit rot in northern highbush blueberry
Abstract Anthracnose fruit rot (AFR), caused by the fungal pathogen Colletotrichum fioriniae, is among the most destructive and widespread fruit disease of blueberry, impacting both yield and overall fruit quality. Blueberry cultivars have highly variable resistance against AFR. To date, this pathogen is largely controlled by applying various fungicides; thus, a more cost-effective and environmentally conscious solution for AFR is needed. Here we report three quantitative trait loci associated with AFR resistance in northern highbush blueberry (Vaccinium corymbosum). Candidate genes within these genomic regions are associated with the biosynthesis of flavonoids (e.g. anthocyanins) and resistance against pathogens. Furthermore, we examined gene expression changes in fruits following inoculation with Colletotrichum in a resistant cultivar, which revealed an enrichment of significantly differentially expressed genes associated with certain specialized metabolic pathways (e.g. flavonol biosynthesis) and pathogen resistance. Using non-targeted metabolite profiling, we identified a flavonol glycoside with properties consistent with a quercetin rhamnoside as a compound exhibiting significant abundance differences among the most resistant and susceptible individuals from the genetic mapping population. Further analysis revealed that this compound exhibits significant abundance differences among the most resistant and susceptible individuals when analyzed as two groups. However, individuals within each group displayed considerable overlapping variation in this compound, suggesting that its abundance may only be partially associated with resistance against C. fioriniae. These findings should serve as a powerful resource that will enable breeding programs to more easily develop new cultivars with superior resistance to AFR and as the basis of future research studies.
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- Award ID(s):
- 1828149
- PAR ID:
- 10513852
- Publisher / Repository:
- Horticulture Research
- Date Published:
- Journal Name:
- Horticulture Research
- Volume:
- 10
- Issue:
- 10
- ISSN:
- 2052-7276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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SUMMARY Sorghum is an important food and feed crop globally; its production is hampered by anthracnose disease caused by the fungal pathogenColletotrichum sublineola(Cs). Here, we report identification and characterization ofANTHRACNOSE RESISTANCE GENE 2(ARG2) encoding a nucleotide‐binding leucine‐rich repeat (NLR) protein that confers race‐specific resistance toCsstrains.ARG2is one of a cluster of severalNLRgenes initially identified in the sorghum differential line SC328C that is resistant to someCsstrains. This cluster shows structural and copy number variations in different sorghum genotypes. Different sorghum lines carrying independentARG2alleles provided the genetic validation for the identity of theARG2gene.ARG2expression is induced byCs, and chitin inducesARG2expression in resistant but not in susceptible lines. ARG2‐mediated resistance is accompanied by higher expression of defense and secondary metabolite genes at early stages of infection, and anthocyanin and zeatin metabolisms are upregulated in resistant plants. Interestingly, ARG2 localizes to the plasma membrane when transiently expressed inNicotiana benthamiana. Importantly,ARG2plants produced higher shoot dry matter than near‐isogenic lines carrying the susceptible allele suggesting an absence of anARG2associated growth trade‐off. Furthermore, ARG2‐mediated resistance is stable at a wide range of temperatures. Our observations open avenues for resistance breeding and for dissecting mechanisms of resistance.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/hr/uhad169
