Přehled vypsaných témat - Ústav ochrany lesů a myslivosti (LDF)Help


Základní údaje

Typ práce:
Disertační práce
Název tématu: Study of viruses infecting Phytophthora cinnamomi and the species included in Phytophthora clade 5.
Stav tématu:
schváleno (prof. Dr. Ing. Libor Jankovský - vedoucí pracoviště)
Vedoucí práce:
Fakulta:
Lesnická a dřevařská fakulta
Garantující pracoviště:
Ústav ochrany lesů a myslivosti (LDF)
Max. počet studentů:
1
Navrhl:
Abstrakt:
Phytophthora spp. are oomycetes belonging to the kingdom Stramenopila. Their morphology and habitat are similar to filamentous fungi but phylogenetically they are closer to brown algae and diatoms. Most of the members of the genus Phytophthora are well-known global plant and forest pathogens causing important economic losses in agriculture, horticulture and forestry industry, and they are major threats to natural ecosystems and biodiversity (Kroon et al. 2012). One of them, P. cinnamomi, firstly isolated from cinnamon trees in Sumatra in 1922 nowadays has a worldwide distribution (Hardham 2005). Its fast spread in many countries has been often occurred inadvertently through contaminated nursery stock and other kind of plant material. It is shown to infect 3000 species, such as peach, avocado, chestnut, rhododendron, camellia, conifers, oaks and eucalyptus etc. (Hardham 2005). A key factor of the aggressive behavior and the onset of P. cinnamomi epidemics is the occurrence of enhancing environmental conditions supporting asexual sporulation and zoospore production (Weste 2003), i.e. according to predictions global warming could result in a more severe scenario for oak in Europe, where the pathogen could expand to the north and east from regions where it already exists (Brasier & Scott 1994).Traditional morphological taxonomy place P. cinnamomi within Clade VI (Waterhouse 1983) but phylogenic studies based on DNA sequencing group it in Clade 7 (Cooke et al. 2000; Kroon et al. 2004). Phytophthora clade 5 is a poorly known group consisting on few species with insufficient taxon sampling and unclear species delimitation (Weir et al. 2015). Although a taxonomic revision is still pointed as necessary (Weir et al. 2015), based on DNA sequencing studies and the gametangial morphology, clade 5 is divided in P. castaneae, causing trunk rot on Castanea crenata (Katsura 1976). P. heveae, rot pathogen of a number of species, such as cocoa, nuts, kauri trees, rhododendron, mango etc. (Zhang et al. 1994). P. agathidicida (Weir et al. 2015), causal agent of collar rot of kauri trees. And, P. cocois (Weir et al. 2015), attacking coconut trees. The distribution of the members of this clade seems to be limited to East Asia, Oceania and Pacific Islands. Study of Phytophthora viruses is just starting, only few species have been described so far and most of them belong to the historically important P. infestans. However, several interesting findings are already obvious. Phytophthora infestans RNA virus 1 (PiRV1) and PiRV2 are likely the first members of two new virus families; and PiRV2 has been pointed out to have an important role in the late blight resurge in 1980s-1990s (Cai et al. 2009). PiRV3 supports the establishment of a new genus not related to virus families (Cai et al. 2013); PiRV4 belongs to the family Narnaviridae (Cai et al. 2012); and Phytophthora endornavirus 1 (PEV1) is the first oomycete virus found in forestry ecosystems. PEV1 was found within an unnamed Phytophthora isolate from Douglas fir in Oregon (Hacker et al. 2005). All these viruses are RNA viruses and no DNA viruses have been described so far. However, a large metagenomic study on DNA viruses in marine ecosystems revealed a potential association between viruses of the Megaviridae family and eukaryotes related to oomycetes (Hingamp et al. 2013). Overall, scarce information exists about their real role in their hosts, structure and transmission. However, viruses can shed light on the understanding of the biology, phylogeny, and epidemiology of their hosts. Here, I propose a PhD topic for a highly motivated student and certain background in molecular biology. The PhD thesis will focus on screening the occurrence of viruses and other viral particles within P. cinnamomi and the species belonging to Phytophthora clade 5. Once the occurrence will be confirmed the viruses will be described based on their genome properties, structure and relation with their hosts. The study of the relation between the virus occurrence and the host will have two main goals, to assess their potential role in controlling these Phytophthora species via triggering hypovirulence and to trace the origin of these pathogens and to reconstruct their pathway of spread and population dynamics. The outcome of this PhD thesis will be at least two articles in international scientific journals, such as Virus Research, Virology, Phytopathology, Archives of Virology or Molecular Plant Pathology, and the student will have to develop at least one internship abroad.



Omezení k tématu

K přihlášení řešitele na téma je potřeba splnění jednoho z následujících omezení

Omezení dle studia
Tabulka zobrazuje omezení dle studia, na které musí být student zapsán, aby se mohl na dané téma přihlásit.

Program
Obor
D-BOTA Botanika
D-BOTA-FYTOLL Fytologie lesa