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Oospores of Pustula helianthicola in sunflower seeds and their role in the epidemiology of white blister rust.
IMA Fungus 2013; 4(2):251-8IF

Abstract

White blister rust (WBR) of sunflower caused by Pustula helianthicola is an important and often underestimated disease in many countries of the world. The epidemiology of the pathogen is not yet fully understood; particularly the role of oospores in primary infection and long distance dispersal. We analysed WBR severity in sunflower under natural conditions and found disease incidence of 97-99 % in fields where infected sunflower had first been observed ca. 8 yr ago. Besides the typical blisters of mitotic sporangia on leaves, large amounts of oospores were observed on the involucral bracts. Inoculation of sunflower seedlings with oospores from these bracts resulted in disease incidence of ca. 30 %, thus confirming their infectivity without a period of dormancy. Bracts of infected flower heads from the field were checked for oospores using a binocular microscope and seeds were checked by light microscopy. Oospores were found in all of the bracts and in up to 28 % of the achenes. Light microscopy revealed that oospores developed in the thin-walled, crushed parenchymatic cells of the inner layer and in the parenchymatic rays of the fibrous layer of the pericarp. Dried seeds were grown in soil to assess the occurrence of seed borne infection. Within 3 wk, up to 58 % of seedlings showed typical WBR pustules on cotyledons. Asymptomatic infections were confirmed in phenotypically healthy plants by using a PCR-based diagnostic test for P. helianthicola. The results showed the importance of oospores of P. helianthicola as the primary inoculum for WBR development in sunflower, and pointed to the potential role of contaminated seeds in the long distance transmission of the pathogen.

Authors+Show Affiliations

Institute of Botany (210), University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany;Institute of Botany (210), University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany;Institute of Botany (210), University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany;

Pub Type(s)

Journal Article

Language

eng

PubMed ID

24563837

Citation

Lava, Sukanya Soonagahalli, et al. "Oospores of Pustula Helianthicola in Sunflower Seeds and Their Role in the Epidemiology of White Blister Rust." IMA Fungus, vol. 4, no. 2, 2013, pp. 251-8.
Lava SS, Heller A, Spring O. Oospores of Pustula helianthicola in sunflower seeds and their role in the epidemiology of white blister rust. IMA Fungus. 2013;4(2):251-8.
Lava, S. S., Heller, A., & Spring, O. (2013). Oospores of Pustula helianthicola in sunflower seeds and their role in the epidemiology of white blister rust. IMA Fungus, 4(2), pp. 251-8. doi:10.5598/imafungus.2013.04.02.10.
Lava SS, Heller A, Spring O. Oospores of Pustula Helianthicola in Sunflower Seeds and Their Role in the Epidemiology of White Blister Rust. IMA Fungus. 2013;4(2):251-8. PubMed PMID: 24563837.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oospores of Pustula helianthicola in sunflower seeds and their role in the epidemiology of white blister rust. AU - Lava,Sukanya Soonagahalli, AU - Heller,Annerose, AU - Spring,Otmar, Y1 - 2013/11/26/ PY - 2013/10/04/received PY - 2013/11/20/accepted PY - 2014/2/25/entrez PY - 2014/2/25/pubmed PY - 2014/2/25/medline KW - Helianthus annuus KW - PCR KW - field monitoring KW - light microscopy KW - oospore seed contamination KW - seed-borne diseases SP - 251 EP - 8 JF - IMA fungus JO - IMA Fungus VL - 4 IS - 2 N2 - White blister rust (WBR) of sunflower caused by Pustula helianthicola is an important and often underestimated disease in many countries of the world. The epidemiology of the pathogen is not yet fully understood; particularly the role of oospores in primary infection and long distance dispersal. We analysed WBR severity in sunflower under natural conditions and found disease incidence of 97-99 % in fields where infected sunflower had first been observed ca. 8 yr ago. Besides the typical blisters of mitotic sporangia on leaves, large amounts of oospores were observed on the involucral bracts. Inoculation of sunflower seedlings with oospores from these bracts resulted in disease incidence of ca. 30 %, thus confirming their infectivity without a period of dormancy. Bracts of infected flower heads from the field were checked for oospores using a binocular microscope and seeds were checked by light microscopy. Oospores were found in all of the bracts and in up to 28 % of the achenes. Light microscopy revealed that oospores developed in the thin-walled, crushed parenchymatic cells of the inner layer and in the parenchymatic rays of the fibrous layer of the pericarp. Dried seeds were grown in soil to assess the occurrence of seed borne infection. Within 3 wk, up to 58 % of seedlings showed typical WBR pustules on cotyledons. Asymptomatic infections were confirmed in phenotypically healthy plants by using a PCR-based diagnostic test for P. helianthicola. The results showed the importance of oospores of P. helianthicola as the primary inoculum for WBR development in sunflower, and pointed to the potential role of contaminated seeds in the long distance transmission of the pathogen. SN - 2210-6340 UR - https://www.unboundmedicine.com/medline/citation/24563837/Oospores_of_Pustula_helianthicola_in_sunflower_seeds_and_their_role_in_the_epidemiology_of_white_blister_rust L2 - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24563837/ DB - PRIME DP - Unbound Medicine ER -