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Upadhaya A, Upadhaya SG, Brueggeman R. The Wheat Stem Rust ( Puccinia graminis f. sp. tritici) Population from Washington Contains the Most Virulent Isolates Reported on Barley. PLANT DISEASE 2022; 106:223-230. [PMID: 34546770 DOI: 10.1094/pdis-06-21-1195-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A diverse sexual population of wheat stem rust, Puccinia graminis f. sp. tritici, exists in the Pacific Northwest region of the United States because of the natural presence of Mahonia spp. that serves as alternate hosts to complete its sexual life cycle. The region appears to be a center of stem rust diversity in North America where novel virulence gene combinations can emerge that could overcome deployed barley and wheat stem rust resistances. A total of 100 single pustule isolates derived from stem rust samples collected from barley in Eastern Washington during the 2019 growing season were assayed for virulence on the two known effective barley stem rust resistance genes/loci, Rpg1 and the rpg4/5-mediated resistance locus (RMRL) at the seedling stage. Interestingly, 99% of the P. graminis f. sp. tritici isolates assayed were virulent on barley variety Morex carrying the Rpg1 gene, and 62% of the isolates were virulent on the variety Golden Promise transformant (H228.2c) that carries a single-copy insertion of the Rpg1 gene from Morex and is more resistant than Morex to many Rpg1 avirulent isolates. Also, 16% of the isolates were virulent on the near isogenic line HQ-1, which carries the RMRL introgression from the barley line Q21861 in the susceptible Harrington background. Alarmingly, 10% of the isolates were virulent on barley line Q21861, which contains both Rpg1 and RMRL. Thus, we report on the first P. graminis f. sp. tritici isolates worldwide with virulence on both Rpg1 and RMRL when stacked together, representing the most virulent P. graminis f. sp. tritici isolates reported on barley.
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Affiliation(s)
- Arjun Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164
| | - Sudha Gc Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164
| | - Robert Brueggeman
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164
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Ameen G, Solanki S, Sager-Bittara L, Richards J, Tamang P, Friesen TL, Brueggeman RS. Mutations in a barley cytochrome P450 gene enhances pathogen induced programmed cell death and cutin layer instability. PLoS Genet 2021; 17:e1009473. [PMID: 34914713 PMCID: PMC8769293 DOI: 10.1371/journal.pgen.1009473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 01/19/2022] [Accepted: 11/26/2021] [Indexed: 12/04/2022] Open
Abstract
Disease lesion mimic mutants (DLMMs) are characterized by the spontaneous development of necrotic spots with various phenotypes designated as necrotic (nec) mutants in barley. The nec mutants were traditionally considered to have aberrant regulation of programmed cell death (PCD) pathways, which have roles in plant immunity and development. Most barley nec3 mutants express cream to orange necrotic lesions contrasting them from typical spontaneous DLMMs that develop dark pigmented lesions indicative of serotonin/phenolics deposition. Barley nec3 mutants grown under sterile conditions did not exhibit necrotic phenotypes until inoculated with adapted pathogens, suggesting that they are not typical DLMMs. The F2 progeny of a cross between nec3-γ1 and variety Quest segregated as a single recessive susceptibility gene post-inoculation with Bipolaris sorokiniana, the causal agent of the disease spot blotch. Nec3 was genetically delimited to 0.14 cM representing 16.5 megabases of physical sequence containing 149 annotated high confidence genes. RNAseq and comparative analysis of the wild type and five independent nec3 mutants identified a single candidate cytochrome P450 gene (HORVU.MOREX.r2.6HG0460850) that was validated as nec3 by independent mutations that result in predicted nonfunctional proteins. Histology studies determined that nec3 mutants had an unstable cutin layer that disrupted normal Bipolaris sorokiniana germ tube development. At the site of pathogen infection, plant defense mechanisms rely on controlled programmed cell death (PCD) to sequester biotrophic pathogens that require living cells to extract nutrients from the host. However, these defense mechanisms are hijacked by necrotrophic plant pathogens that purposefully induce PCD to feed on the dead cells, thus facilitating further disease development. Thus, understanding PCD responses is important for resistance to both classes of pathogens. We characterized five independent disease lesion mimic mutants of barley designated necrotic 3 (nec3) that show aberrant regulation of PCD responses upon pathogen challenge. A cytochrome P450 gene was identified as Nec3 encoding a Tryptamine 5-Hydroxylase that functions as a terminal serotonin biosynthetic enzyme in the Tryptophan pathway of plants. We posit that nec3 mutants have disrupted serotonin biosynthesis resulting in expanded PCD, necrotrophic pathogen susceptibility and cutin layer instability. The nec3 mutants show expanded PCD and disease susceptibility of pathogen-induced necrotic lesions, suggesting a role of serotonin to sequester PCD and suppress pathogen colonization. The identification of Nec3 will facilitate functional analysis to elucidate the role that serotonin plays in the elicitation or suppression of PCD immunity responses to diverse pathogens and the effects it has on cutin layer biosynthesis.
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Affiliation(s)
- Gazala Ameen
- Department of Agronomy, Horticulture & Plant Science, South Dakota State University, Brookings, South Dakota, United States of America
| | - Shyam Solanki
- Department of Agronomy, Horticulture & Plant Science, South Dakota State University, Brookings, South Dakota, United States of America
| | - Lauren Sager-Bittara
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, United States of America
| | - Jonathan Richards
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America
| | - Prabin Tamang
- USDA-ARS, Natural Products Utilization Research Unit, Oxford, Mississippi, United States of America
| | - Timothy L. Friesen
- USDA-ARS, Red River Valley Agricultural Research Center, Cereal Crops Research Unit, Fargo, North Dakota, United States of America
| | - Robert S. Brueggeman
- Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, United States of America
- * E-mail:
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Sánchez-Martín J, Keller B. NLR immune receptors and diverse types of non-NLR proteins control race-specific resistance in Triticeae. CURRENT OPINION IN PLANT BIOLOGY 2021; 62:102053. [PMID: 34052730 DOI: 10.1016/j.pbi.2021.102053] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/01/2021] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
Recent progress in large-scale sequencing, genomics, and rapid gene isolation techniques has accelerated the identification of race-specific resistance (R) genes and their corresponding avirulence (Avr) genes in wheat, barley, rye, and their wild relatives. Here, we describe the growing repertoire of identified R and Avr genes with special emphasis on novel R gene architectures, revealing that there is a large diversity of proteins encoded by race-specific resistance genes that extends beyond the canonical nucleotide-binding domain leucine-rich repeat proteins. Immune receptors with unique domain architectures controlling race-specific resistance possibly reveal novel aspects on the biology of host-pathogen interactions. We conclude that the polyploid cereal genomes have a large evolutionary potential to generate diverse types of resistance genes.
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Affiliation(s)
- Javier Sánchez-Martín
- Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland.
| | - Beat Keller
- Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland.
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Rabbi SMHA, Kumar A, Mohajeri Naraghi S, Sapkota S, Alamri MS, Elias EM, Kianian S, Seetan R, Missaoui A, Solanki S, Mergoum M. Identification of Main-Effect and Environmental Interaction QTL and Their Candidate Genes for Drought Tolerance in a Wheat RIL Population Between Two Elite Spring Cultivars. Front Genet 2021; 12:656037. [PMID: 34220939 PMCID: PMC8249774 DOI: 10.3389/fgene.2021.656037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/13/2021] [Indexed: 01/22/2023] Open
Abstract
Understanding the genetics of drought tolerance can expedite the development of drought-tolerant cultivars in wheat. In this study, we dissected the genetics of drought tolerance in spring wheat using a recombinant inbred line (RIL) population derived from a cross between a drought-tolerant cultivar, ‘Reeder’ (PI613586), and a high-yielding but drought-susceptible cultivar, ‘Albany.’ The RIL population was evaluated for grain yield (YLD), grain volume weight (GVW), thousand kernel weight (TKW), plant height (PH), and days to heading (DH) at nine different environments. The Infinium 90 k-based high-density genetic map was generated using 10,657 polymorphic SNP markers representing 2,057 unique loci. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. One novel QTL for drought tolerance was identified on chromosome 2D. In silico expression analysis of candidate genes underlaying the exclusive QTLs associated with drought stress identified the enrichment of ribosomal and chloroplast photosynthesis-associated proteins showing the most expression variability, thus possibly contributing to stress response by modulating the glycosyltransferase (TraesCS6A01G116400) and hexosyltransferase (TraesCS7B01G013300) unique genes present in QTL 21 and 24, respectively. While both parents contributed favorable alleles to these QTL, unexpectedly, the high-yielding and less drought-tolerant parent contributed desirable alleles for drought tolerance at four out of six loci. Regardless of the origin, all QTL with significant drought tolerance could assist significantly in the development of drought-tolerant wheat cultivars, using genomics-assisted breeding approaches.
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Affiliation(s)
- S M Hisam Al Rabbi
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Ajay Kumar
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | | | - Suraj Sapkota
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA, United States
| | - Mohammed S Alamri
- Department of Food Science and Nutrition, King Saud University, Riyadh, Saudi Arabia
| | - Elias M Elias
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Shahryar Kianian
- USDA-ARS Cereal Disease Laboratory, University of Minnesota, St. Paul, MN, United States
| | - Raed Seetan
- Department of Computer Science, Slippery Rock University, Slippery Rock, PA, United States
| | - Ali Missaoui
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA, United States.,Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, United States
| | - Shyam Solanki
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
| | - Mohamed Mergoum
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA, United States.,Department of Crop and Soil Sciences, University of Georgia, Griffin, GA, United States
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Tamang P, Richards JK, Solanki S, Ameen G, Sharma Poudel R, Deka P, Effertz K, Clare SJ, Hegstad J, Bezbaruah A, Li X, Horsley RD, Friesen TL, Brueggeman RS. The Barley HvWRKY6 Transcription Factor Is Required for Resistance Against Pyrenophora teres f. teres. Front Genet 2021; 11:601500. [PMID: 33519904 PMCID: PMC7844392 DOI: 10.3389/fgene.2020.601500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/14/2020] [Indexed: 11/25/2022] Open
Abstract
Barley is an important cereal crop worldwide because of its use in the brewing and distilling industry. However, adequate supplies of quality malting barley are threatened by global climate change due to drought in some regions and excess precipitation in others, which facilitates epidemics caused by fungal pathogens. The disease net form net blotch caused by the necrotrophic fungal pathogen Pyrenophora teres f. teres (Ptt) has emerged as a global threat to barley production and diverse populations of Ptt have shown a capacity to overcome deployed genetic resistances. The barley line CI5791 exhibits remarkably effective resistance to diverse Ptt isolates from around the world that maps to two major QTL on chromosomes 3H and 6H. To identify genes involved in this effective resistance, CI5791 seed were γ-irradiated and two mutants, designated CI5791-γ3 and CI5791-γ8, with compromised Ptt resistance were identified from an M2 population. Phenotyping of CI5791-γ3 and -γ8 × Heartland F2 populations showed three resistant to one susceptible segregation ratios and CI5791-γ3 × -γ8 F1 individuals were susceptible, thus these independent mutants are in a single allelic gene. Thirty-four homozygous mutant (susceptible) CI5791-γ3 × Heartland F2 individuals, representing 68 recombinant gametes, were genotyped via PCR genotype by sequencing. The data were used for single marker regression mapping placing the mutation on chromosome 3H within an approximate 75 cM interval encompassing the 3H CI5791 resistance QTL. Sequencing of the mutants and wild-type (WT) CI5791 genomic DNA following exome capture identified independent mutations of the HvWRKY6 transcription factor located on chromosome 3H at ∼50.7 cM, within the genetically delimited region. Post transcriptional gene silencing of HvWRKY6 in barley line CI5791 resulted in Ptt susceptibility, confirming that it functions in NFNB resistance, validating it as the gene underlying the mutant phenotypes. Allele analysis and transcript regulation of HvWRKY6 from resistant and susceptible lines revealed sequence identity and upregulation upon pathogen challenge in all genotypes analyzed, suggesting a conserved transcription factor is involved in the defense against the necrotrophic pathogen. We hypothesize that HvWRKY6 functions as a conserved signaling component of defense mechanisms that restricts Ptt growth in barley.
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Affiliation(s)
- Prabin Tamang
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | - Jonathan K Richards
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA, United States
| | - Shyam Solanki
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
| | - Gazala Ameen
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
| | - Roshan Sharma Poudel
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | - Priyanka Deka
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND, United States
| | - Karl Effertz
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
| | - Shaun J Clare
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
| | - Justin Hegstad
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Achintya Bezbaruah
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND, United States
| | - Xuehui Li
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Richard D Horsley
- Department of Plant Sciences, North Dakota State University, Fargo, ND, United States
| | - Timothy L Friesen
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States.,Cereal Crops Research Unit, United States Department of Argiculture - Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND, United States
| | - Robert S Brueggeman
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States.,Department of Crop and Soil Sciences, Washington State University, Pullman, WA, United States
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Abstract
Understanding biology and genetics at molecular level has become very important for dissection and manipulation of genome architecture for addressing evolutionary and taxonomic questions. Knowledge of genetic variation and genetic relationship among genotypes is an important consideration for classification, utilization of germplasm resources, and breeding. Molecular markers have contributed significantly in this respect and have been widely used in plant science in a number of ways, including genetic fingerprinting, diagnostics, identification of duplicates and selection of core collections, determination of genetic distances, genome analysis, development of molecular maps, and identification of markers associated with desirable breeding traits. The application of molecular markers largely depends on the type of markers employed, distribution of markers in the genome, type of loci they amplify, level of polymorphism, and reproducibility of products. Among many DNA markers available, random amplified polymorphic DNA (RAPD) is the simplest, is cost-effective, and can be performed in a moderate laboratory for most of its applications. In addition, RAPDs can touch much of the genome and has the advantage that no prior knowledge of the genome under research is necessary. The recent improvements in the RAPD technique like arbitrarily primed polymerase chain reaction (AP-PCR), sequence characterized amplified region (SCAR), DNA amplification fingerprinting (DAF), sequence-related amplified polymorphism (SRAP), cleaved amplified polymorphic sequences (CAPS), random amplified microsatellite polymorphism (RAMPO), and random amplified hybridization microsatellites (RAHM) can complement the shortcomings of RAPDs and have enhanced the utility of this simple technique for specific applications. Simple protocols for these techniques are presented along with the applications of RAPD in genetic diversity analysis, mapping, varietal identification, genetic fidelity testing, etc.
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Solanki S, Ameen G, Zhao J, Flaten J, Borowicz P, Brueggeman RS. Visualization of spatial gene expression in plants by modified RNAscope fluorescent in situ hybridization. PLANT METHODS 2020; 16:71. [PMID: 32467719 PMCID: PMC7229616 DOI: 10.1186/s13007-020-00614-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 05/11/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND In situ analysis of biomarkers such as DNA, RNA and proteins are important for research and diagnostic purposes. At the RNA level, plant gene expression studies rely on qPCR, RNAseq and probe-based in situ hybridization (ISH). However, for ISH experiments poor stability of RNA and RNA based probes commonly results in poor detection or poor reproducibility. Recently, the development and availability of the RNAscope RNA-ISH method addressed these problems by novel signal amplification and background suppression. This method is capable of simultaneous detection of multiple target RNAs down to the single molecule level in individual cells, allowing researchers to study spatio-temporal patterning of gene expression. However, this method has not been optimized thus poorly utilized for plant specific gene expression studies which would allow for fluorescent multiplex detection. Here we provide a step-by-step method for sample collection and pretreatment optimization to perform the RNAscope assay in the leaf tissues of model monocot plant barley. We have shown the spatial distribution pattern of HvGAPDH and the low expressed disease resistance gene Rpg1 in leaf tissue sections of barley and discuss precautions that should be followed during image analysis. RESULTS We have shown the ubiquitous HvGAPH and predominantly stomatal guard cell associated subsidiary cell expressed Rpg1 expression pattern in barley leaf sections and described the improve RNAscope methodology suitable for plant tissues using confocal laser microscope. By addressing the problems in the sample collection and incorporating additional sample backing steps we have significantly reduced the section detachment and experiment failure problems. Further, by reducing the time of protease treatment, we minimized the sample disintegration due to over digestion of barley tissues. CONCLUSIONS RNAscope multiplex fluorescent RNA-ISH detection is well described and adapted for animal tissue samples, however due to morphological and structural differences in the plant tissues the standard protocol is deficient and required optimization. Utilizing barley specific HvGAPDH and Rpg1 RNA probes we report an optimized method which can be used for RNAscope detection to determine the spatial expression and semi-quantification of target RNAs. This optimized method will be immensely useful in other plant species such as the widely utilized Arabidopsis.
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Affiliation(s)
- Shyam Solanki
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99163 USA
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050 USA
| | - Gazala Ameen
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99163 USA
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050 USA
| | - Jin Zhao
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58108-6050 USA
| | - Jordan Flaten
- Department of Animal Sciences, North Dakota State University, Fargo, ND 58108-6050 USA
| | - Pawel Borowicz
- Department of Animal Sciences, North Dakota State University, Fargo, ND 58108-6050 USA
| | - Robert S. Brueggeman
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99163 USA
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050 USA
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