Editorial

1267 KiB

Open AccessEditorial

Narrative History of the Resistance Screening Center: It’s Origins, Leadership and Partial List of Public Benefits and Scientific Contributions

by Ellis Cowling and Carol Young

Forests 2013, 4(3), 666-692; https://0-doi-org.brum.beds.ac.uk/10.3390/f4030666 - 22 Aug 2013

Cited by 12 | Viewed by 7981

Abstract

Forty years ago, the US Department of Agriculture (USDA) Forest Service developed and currently operates the Resistance Screening Center near Asheville, North Carolina, as a service to both industry and university-based tree improvement programs and tree-seed exporting companies in the southern US, Mexico, [...] Read more.

Forty years ago, the US Department of Agriculture (USDA) Forest Service developed and currently operates the Resistance Screening Center near Asheville, North Carolina, as a service to both industry and university-based tree improvement programs and tree-seed exporting companies in the southern US, Mexico, and Central America. Seed lots from more than 15,000 selections of slash and loblolly pines have been evaluated for genetically-controlled resistance to fusiform rust and other diseases including pitch canker, dogwood anthracnose, and brown spot needle blight. The screening system uses a greenhouse-based artificial inoculation system with controlled density of inoculum from geographically diverse sources of the rust pathogen. Results are completed in 6–9 months and are reasonably well-correlated with field-based progeny tests. Operating costs of the Center are shared by both the USDA Forest Service and its clients. The technologically sophisticated methods and professional skills of the Center staff have been applied to facilitate and accelerate progress in region-wide timber production, scientific understanding of the fusiform rust pathosystem, and graduate education of forest geneticists and pathologists in universities. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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Research

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211 KiB

Open AccessArticle

Identification of Nine Pathotype-Specific Genes Conferring Resistance to Fusiform Rust in Loblolly Pine (Pinus taeda L.)

by Henry V. Amerson, C. Dana Nelson, Thomas L. Kubisiak, E. George Kuhlman and Saul A. Garcia

Forests 2015, 6(8), 2739-2761; https://0-doi-org.brum.beds.ac.uk/10.3390/f6082739 - 07 Aug 2015

Cited by 14 | Viewed by 5502

Abstract

Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for [...] Read more.

Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust resistance genes (Fr genes) are described here including the specific methods to determine each and their localization on the reference genetic map of loblolly pine. Understanding how these and other apparent Fr genes in loblolly pine and other rust-susceptible pines impact resistance screening, parental and progeny selection, and family and clonal deployment is an important area in forest genetics research and operational tree breeding. The documentation of these Fr genes is a key piece of information towards gaining that understanding and ultimately improving breeding and deployment strategies. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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1077 KiB

Open AccessArticle

Mapping Fusiform Rust Resistance Genes within a Complex Mating Design of Loblolly Pine

by Tania Quesada, Marcio F.R. Resende Jr., Patricio Muñoz, Jill L. Wegrzyn, David B. Neale, Matias Kirst, Gary F. Peter, Salvador A. Gezan, C. Dana Nelson and John M. Davis

Forests 2014, 5(2), 347-362; https://0-doi-org.brum.beds.ac.uk/10.3390/f5020347 - 24 Feb 2014

Cited by 16 | Viewed by 7629

Abstract

Fusiform rust resistance can involve gene-for-gene interactions where resistance (Fr) genes in the host interact with corresponding avirulence genes in the pathogen, Cronartium quercuum f.sp. fusiforme (Cqf). Here, we identify trees with Fr genes in a loblolly pine population [...] Read more.

Fusiform rust resistance can involve gene-for-gene interactions where resistance (Fr) genes in the host interact with corresponding avirulence genes in the pathogen, Cronartium quercuum f.sp. fusiforme (Cqf). Here, we identify trees with Fr genes in a loblolly pine population derived from a complex mating design challenged with two Cqf inocula (one gall and 10 gall mixtures). We used single nucleotide polymorphism (SNP) genotypes at sufficient density to ensure linkage between segregating markers and Fr genes identifying SNPs that explained high proportions of variance in disease incidence using BayesCp, that also were significant using Bayesian Association with Missing Data (BAMD) software. Two SNPs mapped near Fr1 and generated significant LOD scores in single marker regression analyses for Fr1/fr1 parent 17 as well as four other parents. One SNP mapped near Fr8 and was significant for parent 28. Two SNPs mapped to linkage groups not previously shown to contain Fr genes and were significant for three parents. Parent 2 showed evidence of Fr gene stacking. Our results suggest that it is feasible to identify trees segregating for Fr genes, and to map Fr genes, based on parental analysis of SNPs that cosegregate with disease incidence in designed resistance screening trials. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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747 KiB

Open AccessArticle

Potentials for Mutually Beneficial Collaboration Between FIA Specialists and IEG-40 Pathologists and Geneticists Working on Fusiform Rust

by Ellis Cowling and KaDonna Randolph

Forests 2013, 4(4), 1220-1231; https://0-doi-org.brum.beds.ac.uk/10.3390/f4041220 - 17 Dec 2013

Cited by 3 | Viewed by 5614

Abstract

The purpose of this article is to encourage development of an enduring mutually beneficial collaboration between data and information analysts in the US Forest Service’s “Enhanced Forest Inventory and Analysis (FIA) Program” and forest pathologists and geneticists in the information exchange group (IEG) [...] Read more.

The purpose of this article is to encourage development of an enduring mutually beneficial collaboration between data and information analysts in the US Forest Service’s “Enhanced Forest Inventory and Analysis (FIA) Program” and forest pathologists and geneticists in the information exchange group (IEG) titled “Genetics and Breeding of Southern Forest Trees.” The goal of this collaborative partnership is to take full advantage of the Forest Health Monitoring capabilities within the Enhanced FIA Program to provide up-to-date information on the incidence of fusiform rust on loblolly and slash pine stands in the Southern United States and to periodically report the status of the rust epidemic in this region. Our initial analysis of 2000–2011 FIA data demonstrates that careful analysis and interpretation of results from continuing FIA observations can provide valuable guidance for optimizing the performance of forest tree improvement programs in this region. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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728 KiB

Open AccessArticle

Stability of Slash Pine Families with Major Gene and Partial Resistance to Single-Gall and Mixed-Gall Inocula of Cronartium quercuum fusiforme in Greenhouse Studies

by Karina P. Gramacho, Robert A. Schmidt and Thomas Miller

Forests 2013, 4(2), 488-499; https://0-doi-org.brum.beds.ac.uk/10.3390/f4020488 - 20 Jun 2013

Cited by 3 | Viewed by 5533

Abstract

Single-gall and mixed-gall inocula from fusiform rust (Cronartium quercuum fusiforme) galls in field studies were used in greenhouse tests to investigate their pathogenic variability and the temporal and spatial stability of fusiform rust incidence of resistant slash pine (Pinus elliottii [...] Read more.

Single-gall and mixed-gall inocula from fusiform rust (Cronartium quercuum fusiforme) galls in field studies were used in greenhouse tests to investigate their pathogenic variability and the temporal and spatial stability of fusiform rust incidence of resistant slash pine (Pinus elliottii var. elliottii) seedlings. Analyses of variance showed significant main effects for families and inocula and for the interactions of families and inocula indicating abundant pathogenic variation and differential family resistance. Averaged over all families and inocula, there were no significant differences between sequential inocula, i.e., inocula from successive generations of the pathogen. However, when analyzed separately Family R1 with segregated major gene resistance showed increased rust incidence with successive generations of the pathogen. Also Family R1 accounted for a major portion of the temporal (51.4%) and spatial (49.6%) interaction sum of squares. In contrast the other resistant families each accounted for a minor portion of this statistic. These results indicate pathogen virulence toward major gene resistance, possible selection for virulence and the relative instability of Family R1 compared with other resistance families. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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688 KiB

Open AccessArticle

Comparative Histopathology of Host Reaction Types in Slash Pine Resistant to Cronartium quercuum f. sp. fusiforme

by Karina P. Gramacho, Thomas Miller and Robert A. Schmidt

Forests 2013, 4(2), 319-328; https://0-doi-org.brum.beds.ac.uk/10.3390/f4020319 - 10 May 2013

Cited by 4 | Viewed by 5557

Abstract

Histological examinations of the host reaction types (RTs); short galls, rough galls and smooth galls in slash pine seedlings inoculated with Cronartium quercuum f. sp. fusiforme revealed host reaction zone(s) [RZ(s)]. These RZs differed among the host RTs in location and pattern of [...] Read more.

Histological examinations of the host reaction types (RTs); short galls, rough galls and smooth galls in slash pine seedlings inoculated with Cronartium quercuum f. sp. fusiforme revealed host reaction zone(s) [RZ(s)]. These RZs differed among the host RTs in location and pattern of occurrence in the stem, staining reaction, periderm formation and amount of fungal colonization. The RZ within short galls were wide, deep in the cortex, continuous around the stem, bordered on both sides by a well-developed periderm encircling the stem with limited fungal colonization. The RZ of the rough galls lacked a periderm, were small, numerous and discontinuous around the stem circumference, being separated by symptomatic tissue typical of a susceptible reaction. Fungal colonization of the rough galls was limited and hyphae and haustoria were encrusted. The RZ of the smooth galls were small and narrow conforming to the stem circumference, shallow in the cortex and interconnected by symptomatic tissues typical of a susceptible reaction. A narrow periderm developed along the innermost portion of the RZ in smooth galls and fungal colonization was abundant in the cortex. We suggest that the RTs large galls (rough and smooth), short galls, and hypersensitive-like stem lesions represent increasing resistance to the fusiform rust pathogen. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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Review

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2614 KiB

Open AccessReview

Genetic Resistance to Fusiform Rust in Southern Pines and White Pine Blister Rust in White Pines—A Contrasting Tale of Two Rust Pathosystems—Current Status and Future Prospects

by Richard A. Sniezko, Jason Smith, Jun-Jun Liu and Richard C. Hamelin

Forests 2014, 5(9), 2050-2083; https://0-doi-org.brum.beds.ac.uk/10.3390/f5092050 - 01 Sep 2014

Cited by 72 | Viewed by 10721

Abstract

Damage or mortality from pathogens can reduce productivity of forest plantations, as well as significantly harm natural forest ecosystems. Genetic resistance within the host species is the first line of defense for tree species. Resistance breeding programs for the native fusiform rust and [...] Read more.

Damage or mortality from pathogens can reduce productivity of forest plantations, as well as significantly harm natural forest ecosystems. Genetic resistance within the host species is the first line of defense for tree species. Resistance breeding programs for the native fusiform rust and exotic (to North America) white pine blister rust diseases are two of the longest concerted efforts in forest trees, spanning more than 50 years. Advances in developing greater genetic resistance have been made in both pathosystems, but unique challenges and opportunities in each system translate to different approaches. Fusiform rust resistance programs have mainly emphasized complete resistance, while partial resistance plays a prominent role in white pine blister rust resistance programs. Advances in the development of molecular genetic tools now permit investigations in conifers and their associated rust pathogens. Good progress has been made in identifying resistant populations and understanding resistance in these pathosystems, and resistant stock is now being used extensively for reforestation and restoration. These programs represent great success stories brought to fruition by the long-term efforts. However, continued support will be needed to enhance the level and fully realize the potential of durable genetic resistance in these invaluable North American conifer species. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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674 KiB

Open AccessReview

Leaf Rust of Wheat: Pathogen Biology, Variation and Host Resistance

by James Kolmer

Forests 2013, 4(1), 70-84; https://0-doi-org.brum.beds.ac.uk/10.3390/f4010070 - 16 Jan 2013

Cited by 99 | Viewed by 17594

Abstract

Rusts are important pathogens of angiosperms and gymnosperms including cereal crops and forest trees. With respect to cereals, rust fungi are among the most important pathogens. Cereal rusts are heteroecious and macrocyclic requiring two taxonomically unrelated hosts to complete a five spore [...] Read more.

Rusts are important pathogens of angiosperms and gymnosperms including cereal crops and forest trees. With respect to cereals, rust fungi are among the most important pathogens. Cereal rusts are heteroecious and macrocyclic requiring two taxonomically unrelated hosts to complete a five spore stage life cycle. Cereal rust fungi are highly variable for virulence and molecular polymorphism. Leaf rust, caused by Puccinia triticina is the most common rust of wheat on a worldwide basis. Many different races of P. triticina that vary for virulence to leaf rust resistance genes in wheat differential lines are found annually in the US. Molecular markers have been used to characterize rust populations in the US and worldwide. Highly virulent races of P. triticina are selected by leaf rust resistance genes in the soft red winter wheat, hard red winter wheat and hard red spring wheat cultivars that are grown in different regions of the US. Cultivars that only have race-specific leaf rust resistance genes that are effective in seedling plants lose their effective resistance and become susceptible within a few years of release. Cultivars with combinations of race non-specific resistance genes have remained resistant over a period of years even though races of the leaf rust population have changed constantly. Full article

(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)

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