Seasonal fruiting and sporulation of Thekopsora and Chrysomyxa cone rusts in Norway spruce cones and alternate hosts in Finland

Kaitera, Juha; Tillman-Sutela, Eila; Kauppi, Anneli

doi:10.1139/x09-070

Cited by 20 publications

(77 citation statements)

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“…The aecial sporulation of the C. ledi occurred in cones in the mid-and late summer, somewhat later than sporulation of C. pirolata, although spermogonia and aecia of both species were concurrent in cone scales. Spermogonia and aecia of C. ledi were smaller and aeciospore morphology was distinct from the common cone pathogens C. pirolata (Gäumann, 1959;Sutherland et al, 1984;Crane, 2001;Kaitera et al, 2009), C. woroninii (McBeath, 1984 and other rust reported to occur in Norway spruce cones (Gäumann, 1959). Aeciospore size and ultrastructure were similar to C. ledi (Crane, 2001), but the length and width of ovoid spermatia were somewhat greater than those described before (Crane, 2001).…”

Section: Discussionmentioning

confidence: 97%

“…The morphology of the rust observed using both a stereomicroscope and FESEM was distinct from rusts known to occur on cone scales of Picea spp. (Gäumann, 1959;McBeath, 1982;Sutherland et al, 1984;Crane, 2001;Kaitera et al, 2009). The fruiting and sporulation of the rust resembled that of C. ledi and C. ledicola Lagerh.…”

Section: Discussionmentioning

confidence: 99%

“…Both T. areolata and C. pirolata occurred infrequently in the current-year cones, while T. areolata was the most common cone pathogen in 1-year-old cones (Kaitera et al, 2009). Fruitbodies of the other rust species were not observed in cone scales of currentyear cones collected in the seed orchard (southern Finland) between late May and mid-June in 2007.…”

Section: Frequency and Morphology Of The Rust In Conesmentioning

confidence: 95%

“…The other half of the split cones were fixed in FAA (ethanolÁglacial acetic acidÁformalin 85:5:10). A more thorough description of the study areas and methods is provided in Kaitera et al (2009).…”

Section: Sample Collectionmentioning

confidence: 99%

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Chrysomyxaledi, a new rust fungus sporulating in cone scales ofPicea abiesin Finland

Kaitera¹,

Tillman-Sutela²,

Kauppi

2010

Scandinavian Journal of Forest Research

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Seasonal fruiting and sporulation of cone rusts were investigated in Norway spruce cones during the growing season of 2007, a year after an excellent cone crop and a severe outbreak of rust. Current-year and 1-year-old cones were collected bimonthly to monthly from case-stands in southern and northern Finland and checked for rust fruitbodies. A previously unreported species of rust formed spermogonia and aecia, and sporulated on the cone scales of Norway spruce in two study areas. Morphologically, the rust was distinct from other spruce cone rusts and, based on ultrastructure of aecia and aeciospores, most closely resembled Chrysomyxa ledi. Molecular analysis of the aeciospores confirmed that the rust belonged to the C. ledi/C. rhododendri complex. The rust fruited frequently but only colonized a few scales per cone and presumably had a minor effect on cone development and seed crop.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Frequency and Morphology Of The Rust In Conesmentioning

confidence: 95%

Section: Sample Collectionmentioning

confidence: 99%

See 2 more Smart Citations

Chrysomyxaledi, a new rust fungus sporulating in cone scales ofPicea abiesin Finland

Kaitera¹,

Tillman-Sutela²,

Kauppi

2010

Scandinavian Journal of Forest Research

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“…Picea abies (L.) Karst is known to have large betweenyears variation in flowering and cone production (Nikkanen & Ruotsalainen 2000), which was observed also in some seed orchards and natural forests in the late 2000s (Kaitera et al 2009). Cone rusts regularly destroy cones and seeds of Picea spp.…”

Section: Introductionmentioning

confidence: 97%

Germination capacity ofThekopsora areolataaeciospores and the effect of cone rusts on seeds ofPicea abies

Kaitera¹,

Tillman-Sutela²

2013

Scandinavian Journal of Forest Research

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Mature Norway spruce (Picea abies) cones of different ages and colonized by Thekopsora areolata were collected in northern Finland 2009-2010. The germination capacity of aeciospores collected from intact aecia was measured on water agar and compared across cone age. Seed formation was investigated in healthy cones and those infected by T. areolata, Chrysomyxa pirolata, Chrysomyxa ledi, and seed germination was also measured for healthy cones and those infected by T. areolata. Unsporulated aecia of T. areolata occurred in 0-to 4-year-old cones. Aeciospores from current-year cones did not germinate and the germination capacity was significantly higher in one-to three-year-old cones than in older or current-year cones. However, a small number of aeciospores remained viable in four-year-old cones. Seed number and apparent health were significantly lower in cones infected by T. areolata and C. pirolata than in healthy cones or cones infected by C. ledi. Seed germination was significantly lower in cones infected with T. areolata compared to seeds from healthy cones. Our results suggest that infected cones more than one-year old continue to spread T. areolata for several years after the initial infection and fruiting, and thus promote the likelihood of epidemics and virulence of local outbreaks. Although cones infected by T. areolata and C. pirolata form significantly fewer seeds and of diminished viability, C. ledi does not appear to affect seed formation and health in Norway spruce. We recommend all rust-infected cones to be removed from orchards to improve stand health, reduce the risk of local outbreaks, and thereby increase the production and quality of Norway spruce seed.

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Genetic evidence for sexual reproduction and multiple infections of Norway spruce cones by the rust fungus Thekopsora areolata

Capador

Samils

Kaitera

et al. 2020

Ecology and Evolution

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Rust fungi are obligate parasites, of plants, with complex and in many cases poorly known life cycles which may include host alteration and up to five spore types with haploid, diploid, and dikaryotic nuclear stages. This study supports that Thekopasora areolata , the causal agent of cherry‐spruce rust in Norway spruce, is a macrocyclic heteroecious fungus with all five spore stages which uses two host plants Prunus padus and Picea abies to complete its life cycle. High genotypic diversity without population structure was found, which suggests predominantly sexual reproduction, random mating and a high gene flow within and between the populations in Fennoscandia. There was no evidence for an autoecious life cycle resulting from aeciospore infection of pistillate cones that would explain the previously reported rust epidemics without the alternate host. However, within cones and scales identical multilocus genotypes were repeatedly sampled which can be explained by vegetative growth of the fertilized mycelia or repeated mating of mycelium by spermatia of the same genotype. The high genotypic diversity within cones and haplotype inference show that each pistillate cone is infected by several basidiospores. This study provides genetic evidence for high gene flow, sexual reproduction, and multiple infections of Norway spruce cone by the rust fungus T. areolata which expands the general understanding of the biology of rust fungi.

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Seasonal fruiting and sporulation of Thekopsora and Chrysomyxa cone rusts in Norway spruce cones and alternate hosts in Finland

Cited by 20 publications

References 10 publications

Chrysomyxaledi, a new rust fungus sporulating in cone scales ofPicea abiesin Finland

Chrysomyxaledi, a new rust fungus sporulating in cone scales ofPicea abiesin Finland

Germination capacity ofThekopsora areolataaeciospores and the effect of cone rusts on seeds ofPicea abies

Genetic evidence for sexual reproduction and multiple infections of Norway spruce cones by the rust fungus Thekopsora areolata

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