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Dittiger LD, Chaudhary S, Furch ACU, Mithöfer A, Schirawski J. Plant Responses of Maize to Two formae speciales of Sporisorium reilianum Support Recent Fungal Host Jump. Int J Mol Sci 2023; 24:15604. [PMID: 37958588 PMCID: PMC10648682 DOI: 10.3390/ijms242115604] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/20/2023] [Accepted: 10/24/2023] [Indexed: 11/15/2023] Open
Abstract
Host jumps are a major factor for the emergence of new fungal pathogens. In the evolution of smut fungi, a putative host jump occurred in Sporisorium reilianum that today exists in two host-adapted formae speciales, the sorghum-pathogenic S. reilianum f. sp. reilianum and maize-pathogenic S. reilianum f. sp. zeae. To understand the molecular host-specific adaptation to maize, we compared the transcriptomes of maize leaves colonized by both formae speciales. We found that both varieties induce many common defense response-associated genes, indicating that both are recognized by the plant as pathogens. S. reilianum f. sp. reilianum additionally induced genes involved in systemic acquired resistance. In contrast, only S. reilianum f. sp. zeae induced expression of chorismate mutases that function in reducing the level of precursors for generation of the defense compound salicylic acid (SA), as well as oxylipin biosynthesis enzymes necessary for generation of the SA antagonist jasmonic acid (JA). In accordance, we found reduced SA levels as well as elevated JA and JA-Ile levels in maize leaves inoculated with the maize-adapted variety. These findings support a model of the emergence of the maize-pathogenic variety from a sorghum-specific ancestor following a recent host jump.
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Affiliation(s)
- Lukas Dorian Dittiger
- Department of Genetics, Matthias Schleiden Institute, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (L.D.D.); (S.C.)
| | - Shivam Chaudhary
- Department of Genetics, Matthias Schleiden Institute, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (L.D.D.); (S.C.)
| | - Alexandra Charlotte Ursula Furch
- Department of Plant Physiology, Matthias Schleiden Institute, Friedrich Schiller University Jena, Dornburgerstr. 159, 07743 Jena, Germany;
| | - Axel Mithöfer
- Research Group Plant Defense Physiology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany;
| | - Jan Schirawski
- Department of Genetics, Matthias Schleiden Institute, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (L.D.D.); (S.C.)
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Lipps S, Lipka AE, Mideros S, Jamann T. Inhibition of ethylene involved in resistance to E. turcicum in an exotic-derived double haploid maize population. FRONTIERS IN PLANT SCIENCE 2023; 14:1272951. [PMID: 37868313 PMCID: PMC10587583 DOI: 10.3389/fpls.2023.1272951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/19/2023] [Indexed: 10/24/2023]
Abstract
Northern corn leaf blight (NCLB) is an economically important disease of maize. While the genetic architecture of NCLB has been well characterized, the pathogen is known to overcome currently deployed resistance genes, and the role of hormones in resistance to NCLB is an area of active research. The objectives of the study were (i) to identify significant markers associated with resistance to NCLB, (ii) to identify metabolic pathways associated with NCLB resistance, and (iii) to examine role of ethylene in resistance to NCLB. We screened 252 lines from the exotic-derived double haploid BGEM maize population for resistance to NCLB in both field and greenhouse environments. We used a genome wide association study (GWAS) and stepwise regression to identify four markers associated with resistance, followed by a pathway association study tool (PAST) to identify important metabolic pathways associated with disease severity and incubation period. The ethylene synthesis pathway was significant for disease severity and incubation period. We conducted a greenhouse assay in which we inhibited ethylene to examine the role of ethylene in resistance to NCLB. We observed a significant increase in incubation period and a significant decrease in disease severity between plants treated with the ethylene inhibitor and mock-treated plants. Our study confirms the potential of the BGEM population as a source of novel alleles for resistance. We also confirm the role of ethylene in resistance to NCLB and contribute to the growing body of literature on ethylene and disease resistance in monocots.
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Affiliation(s)
| | | | | | - Tiffany Jamann
- Department of Crop Sciences, University of Illinois, Urbana, IL, United States
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Pardo J, Wai CM, Harman M, Nguyen A, Kremling KA, Romay MC, Lepak N, Bauerle TL, Buckler ES, Thompson AM, VanBuren R. Cross-species predictive modeling reveals conserved drought responses between maize and sorghum. Proc Natl Acad Sci U S A 2023; 120:e2216894120. [PMID: 36848555 PMCID: PMC10013860 DOI: 10.1073/pnas.2216894120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 01/30/2023] [Indexed: 03/01/2023] Open
Abstract
Drought tolerance is a highly complex trait controlled by numerous interconnected pathways with substantial variation within and across plant species. This complexity makes it difficult to distill individual genetic loci underlying tolerance, and to identify core or conserved drought-responsive pathways. Here, we collected drought physiology and gene expression datasets across diverse genotypes of the C4 cereals sorghum and maize and searched for signatures defining water-deficit responses. Differential gene expression identified few overlapping drought-associated genes across sorghum genotypes, but using a predictive modeling approach, we found a shared core drought response across development, genotype, and stress severity. Our model had similar robustness when applied to datasets in maize, reflecting a conserved drought response between sorghum and maize. The top predictors are enriched in functions associated with various abiotic stress-responsive pathways as well as core cellular functions. These conserved drought response genes were less likely to contain deleterious mutations than other gene sets, suggesting that core drought-responsive genes are under evolutionary and functional constraints. Our findings support a broad evolutionary conservation of drought responses in C4 grasses regardless of innate stress tolerance, which could have important implications for developing climate resilient cereals.
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Affiliation(s)
- Jeremy Pardo
- Department of Horticulture, Michigan State University, East Lansing, MI48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI48824
- Department of Plant Biology, Michigan State University, East Lansing, MI48824
| | - Ching Man Wai
- Department of Horticulture, Michigan State University, East Lansing, MI48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI48824
| | - Maxwell Harman
- Department of Horticulture, Michigan State University, East Lansing, MI48824
| | - Annie Nguyen
- Department of Horticulture, Michigan State University, East Lansing, MI48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI48824
| | - Karl A. Kremling
- Institute for Genomic Diversity, Cornell University, Ithaca, NY14853
- School of Integrative Plant Science, Cornell University, Ithaca, NY14853
| | - Maria Cinta Romay
- Institute for Genomic Diversity, Cornell University, Ithaca, NY14853
- School of Integrative Plant Science, Cornell University, Ithaca, NY14853
| | - Nicholas Lepak
- Agricultural Research Service, US Department of Agriculture, Ithaca, NY14853
| | - Taryn L. Bauerle
- School of Integrative Plant Science, Cornell University, Ithaca, NY14853
| | - Edward S. Buckler
- Institute for Genomic Diversity, Cornell University, Ithaca, NY14853
- School of Integrative Plant Science, Cornell University, Ithaca, NY14853
- Agricultural Research Service, US Department of Agriculture, Ithaca, NY14853
| | - Addie M. Thompson
- Plant Resilience Institute, Michigan State University, East Lansing, MI48824
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI48824
| | - Robert VanBuren
- Department of Horticulture, Michigan State University, East Lansing, MI48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI48824
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Genomic regions associated with virulence in Setosphaeria turcica identified by linkage mapping in a biparental population. Fungal Genet Biol 2021; 159:103655. [PMID: 34954385 DOI: 10.1016/j.fgb.2021.103655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/17/2021] [Accepted: 12/19/2021] [Indexed: 01/06/2023]
Abstract
Northern corn leaf blight (NCLB) and sorghum leaf blight (SLB) are significant diseases of maize and sorghum, respectively, caused by the filamentous fungus Setosphaeria turcica. Strains of S. turcica are typically host-specific and infect either maize or sorghum. Host specificity in this pathogen is attributed to a single locus for maize and a second distinct locus for sorghum. To identify the genetic basis of host specificity in S. turcica, we generated a biparental population of S. turcica by crossing strains specific to maize and sorghum, phenotyped the population for leaf blight on sorghum and maize, genotyped the population to create a linkage map of S. turcica, and located candidate virulence regions. A total of 190 ascospores from 35 pseudothecia were isolated from the cross of maize and sorghum-specific strains. Greenhouse phenotyping of the biparental population (n = 144) showed independent inheritance of virulence, as indicated by a 1:1:1:1 segregation for virulence to maize, sorghum, both maize and sorghum, and avirulence to both crops. The population and host-specific parent strains were genotyped using genome skim sequencing on an Illumina NovaSeq 6000 platform resulting in over 780 million reads. A total of 32,635 variants including single nucleotide polymorphisms and indels were scored. There was evidence for a large deletion in the sorghum-specific strain of S. turcica. A genetic map consisting of 17 linkage groups spanning 3,069 centimorgans was constructed. Virulence to sorghum and maize mapped on distinct linkage groups with a significant QTL detected for virulence to maize. Furthermore, a single locus each for the in vitro traits hyphal growth rate and conidiation were identified and mapped onto two other linkage groups. In vitro traits did not correlate with in planta virulence complexity, suggesting that virulence on both hosts does not incur a fitness cost. Hyphal growth rate and conidiation were negatively correlated, indicating differences in hyphal growth versus dispersal ability for this pathogen. Identification of genetic regions underlying virulence specificity and saprotrophic growth traits in S. turcica provides a better understanding of the S. turcica- Andropogoneae pathosystem.
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Adhikari P, Mideros SX, Jamann TM. Differential Regulation of Maize and Sorghum Orthologs in Response to the Fungal Pathogen Exserohilum turcicum. FRONTIERS IN PLANT SCIENCE 2021; 12:675208. [PMID: 34113371 PMCID: PMC8185347 DOI: 10.3389/fpls.2021.675208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/26/2021] [Indexed: 06/01/2023]
Abstract
Pathogens that infect more than one host offer an opportunity to study how resistance mechanisms have evolved across different species. Exserohilum turcicum infects both maize and sorghum and the isolates are host-specific, offering a unique system to examine both compatible and incompatible interactions. We conducted transcriptional analysis of maize and sorghum in response to maize-specific and sorghum-specific E. turcicum isolates and identified functionally related co-expressed modules. Maize had a more robust transcriptional response than sorghum. E. turcicum responsive genes were enriched in core orthologs in both crops, but only up to 16% of core orthologs showed conserved expression patterns. Most changes in gene expression for the core orthologs, including hub genes, were lineage specific, suggesting a role for regulatory divergent evolution. We identified several defense-related shared differentially expressed (DE) orthologs with conserved expression patterns between the two crops, suggesting a role for parallel evolution of those genes in both crops. Many of the differentially expressed genes (DEGs) during the incompatible interaction were related to quantitative disease resistance (QDR). This work offers insights into how different hosts with relatively recent divergence interact with a common pathogen. Our results are important for developing resistance to this critical pathogen and understanding the evolution of host-pathogen interactions.
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Adhikari P, Goodrich E, Fernandes SB, Lipka AE, Tranel P, Brown P, Jamann TM. Genetic variation associated with PPO-inhibiting herbicide tolerance in sorghum. PLoS One 2020; 15:e0233254. [PMID: 33052910 PMCID: PMC7556536 DOI: 10.1371/journal.pone.0233254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/26/2020] [Indexed: 11/29/2022] Open
Abstract
Herbicide application is crucial for weed management in most crop production systems, but for sorghum herbicide options are limited. Sorghum is sensitive to residual protoporphyrinogen oxidase (PPO)-inhibiting herbicides, such as fomesafen, and a long re-entry period is required before sorghum can be planted after its application. Improving sorghum for tolerance to such residual herbicides would allow for increased sorghum production and the expansion of herbicide options for growers. In this study, we observed sorghum tolerance to residual fomesafen. To investigate the underlying tolerance mechanism a genome-wide association mapping study was conducted using field-collected sorghum biomass panel (SBP) data, and a greenhouse assay was developed to confirm the field phenotypes. A total of 26 significant SNPs (FDR<0.05), spanning a 215.3 kb region on chromosome 3, were detected. The ten most significant SNPs included two in genic regions (Sobic.003G136800, and Sobic.003G136900) and eight SNPs in the intergenic region encompassing the genes Sobic.003G136700, Sobic.003G136800, Sobic.003G137000, Sobic.003G136900, and Sobic.003G137100. The gene Sobic.003G137100 (PPXI), which encodes the PPO1 enzyme, one of the targets of PPO-inhibiting herbicides, was located 12kb downstream of the significant SNP S03_13152838. We found that PPXI is highly conserved in sorghum and expression does not significantly differ between tolerant and sensitive sorghum lines. Our results suggest that PPXI most likely does not underlie the observed herbicide tolerance. Instead, the mechanism underlying herbicide tolerance in the SBP is likely metabolism-based resistance, possibly regulated by the action of multiple genes. Further research is necessary to confirm candidate genes and their functions.
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Affiliation(s)
- Pragya Adhikari
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
| | - Emma Goodrich
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
| | - Samuel B. Fernandes
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
| | - Alexander E. Lipka
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
| | - Patrick Tranel
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
| | - Patrick Brown
- Department of Plant Sciences, University of California Davis, Davis, CA, United States of America
| | - Tiffany M. Jamann
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States of America
- * E-mail:
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