First Report of Phytophthora nicotianae Causing Root and Basal Stem Rot of Rosmarinus and Thymus and Foliar Blight of Rhododendron in the Czech Republic

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00027073%3A_____%2F22%3AN0000126" target="_blank" >RIV/00027073:_____/22:N0000126 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1094/PDIS-08-21-1712-PDN" target="_blank" >https://doi.org/10.1094/PDIS-08-21-1712-PDN</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

First Report of Phytophthora nicotianae Causing Root and Basal Stem Rot of Rosmarinus and Thymus and Foliar Blight of Rhododendron in the Czech Republic

Popis výsledku v původním jazyce

In 2019 and 2020, wilting, withering, and root and basal stem rot of potted herb plants Rosmarinus officinalis and Thymus vulgaris ‘Faustini’, and leaf spots of Rhododendron ‘Cunningham’s White’ were observed in three localities (private greenery, gardening center, and ornamental nursery) in Prague, western and central Bohemia. The species Phytophthora nicotianae Breda de Haan was consistently isolated from infected tissues on PARPNH (Jung et al. 1996) medium. Isolates formed fluffy to slightly stellate colonies on 20% V8 agar (V8A) plates at 25°C after 5 days, but on carrot agar plates colonies were uniform with no aerial mycelium. The cardinal growth temperatures were: min. 8°C, optimum 27 to 32°C, and max. 37°C on V8A. Radial growth (three isolates) was 7.1 to 7.8 mm/day at 25°C. The isolates were usually heterothallic, but the isolate from Rosmarinus sometimes in old cultures produced smooth-walled, spherical oogonia ranging from 18.7 to 26.6 µm (n = 40) in diameter. Oospores (14.5 to 22.8 μm in diameter, n = 40) were aplerotic with a 0.9- to 1.5-µm-thick wall. Amphigynous antheridia averaged 11.8 × 11.7 µm (height × width, n = 40). Noncaducous papillate (sometimes two papillae occurred) sporangia varied from ellipsoid, ovoid, pyriform, to globose in shape and were 34.3 to 78.6 × 23.0 to 50.1 µm (n = 60). Terminal chlamydospores (n = 60) were 13.5 to 57.5 µm with a 0.7- to 1.5-µm-thick wall. Morphological characteristics resembled those described for P. nicotianae (Erwin and Ribeiro 1996). The isolates were deposited in the Czech Collection of Phytopathogenic Oomycetes of RILOG Pruhonice under nos. 1087.19, 1144.20, and 1101.19. These three isolates were sequenced for the rDNA ITS region, partial NADH1, and partial COX1 gene. Obtained sequences were deposited in GenBank (accession nos. MW762935 to MW762937 and MW762610 to MW762615) and compared with sequences in the GenBank database using BLAST. The ITS sequences showed 99.7 and 100% similarity to reference P. nicotianae sequences (KJ494902 and MH219888). The sequence of isolate 1087.19 showed a 1-bp difference, while isolate 1144.20 contained ambiguous bases. The COX1 and NADH1 sequences of isolates 1087.19 and 1144.20 were identical to reference P. nicotianae sequences (accession nos. MH477752 for COX1 and AY564023 for NADH1). The sequences of isolate 1101.19 differed in two positions in both genes and showed 99.7% similarity to the same reference P. nicotianae sequences. The three isolates were tested for pathogenicity on all three host species (10 plants per isolate per host species). Two-year-old R. officinalis and T. vulgaris plants were inoculated with three 5-mm V8A plugs with mycelium from 7-day-old colonies by inserting into the substrate near the collar. Leaves of 3-year-old Rhododendron ‘Cunningham’s White’ were inoculated with an agar plug near the midrib and sealed by Parafilm on the plant. Control plants were treated in the same manner with sterile agar plugs. R. officinalis and T. vulgaris plants were flooded up to the collar with deionized water for 24 h. All plants were maintained in a greenhouse at 22°C and watered when needed. All inoculated plants showed root rot or leaf necrosis after 10 days, and control plants remained healthy. The pathogen was reisolated from all infected plant tissues and confirmed as P. nicotianae by molecular methods. P. nicotianae is a cosmopolitan pathogen (CABI 2021) and was found on the given hosts in southern Europe. However, this is its first report in the Czech Republic. Its introduction poses a potential risk for the growth of many ornamental and agricultural plants in the country.

Název v anglickém jazyce

First Report of Phytophthora nicotianae Causing Root and Basal Stem Rot of Rosmarinus and Thymus and Foliar Blight of Rhododendron in the Czech Republic

Popis výsledku anglicky

In 2019 and 2020, wilting, withering, and root and basal stem rot of potted herb plants Rosmarinus officinalis and Thymus vulgaris ‘Faustini’, and leaf spots of Rhododendron ‘Cunningham’s White’ were observed in three localities (private greenery, gardening center, and ornamental nursery) in Prague, western and central Bohemia. The species Phytophthora nicotianae Breda de Haan was consistently isolated from infected tissues on PARPNH (Jung et al. 1996) medium. Isolates formed fluffy to slightly stellate colonies on 20% V8 agar (V8A) plates at 25°C after 5 days, but on carrot agar plates colonies were uniform with no aerial mycelium. The cardinal growth temperatures were: min. 8°C, optimum 27 to 32°C, and max. 37°C on V8A. Radial growth (three isolates) was 7.1 to 7.8 mm/day at 25°C. The isolates were usually heterothallic, but the isolate from Rosmarinus sometimes in old cultures produced smooth-walled, spherical oogonia ranging from 18.7 to 26.6 µm (n = 40) in diameter. Oospores (14.5 to 22.8 μm in diameter, n = 40) were aplerotic with a 0.9- to 1.5-µm-thick wall. Amphigynous antheridia averaged 11.8 × 11.7 µm (height × width, n = 40). Noncaducous papillate (sometimes two papillae occurred) sporangia varied from ellipsoid, ovoid, pyriform, to globose in shape and were 34.3 to 78.6 × 23.0 to 50.1 µm (n = 60). Terminal chlamydospores (n = 60) were 13.5 to 57.5 µm with a 0.7- to 1.5-µm-thick wall. Morphological characteristics resembled those described for P. nicotianae (Erwin and Ribeiro 1996). The isolates were deposited in the Czech Collection of Phytopathogenic Oomycetes of RILOG Pruhonice under nos. 1087.19, 1144.20, and 1101.19. These three isolates were sequenced for the rDNA ITS region, partial NADH1, and partial COX1 gene. Obtained sequences were deposited in GenBank (accession nos. MW762935 to MW762937 and MW762610 to MW762615) and compared with sequences in the GenBank database using BLAST. The ITS sequences showed 99.7 and 100% similarity to reference P. nicotianae sequences (KJ494902 and MH219888). The sequence of isolate 1087.19 showed a 1-bp difference, while isolate 1144.20 contained ambiguous bases. The COX1 and NADH1 sequences of isolates 1087.19 and 1144.20 were identical to reference P. nicotianae sequences (accession nos. MH477752 for COX1 and AY564023 for NADH1). The sequences of isolate 1101.19 differed in two positions in both genes and showed 99.7% similarity to the same reference P. nicotianae sequences. The three isolates were tested for pathogenicity on all three host species (10 plants per isolate per host species). Two-year-old R. officinalis and T. vulgaris plants were inoculated with three 5-mm V8A plugs with mycelium from 7-day-old colonies by inserting into the substrate near the collar. Leaves of 3-year-old Rhododendron ‘Cunningham’s White’ were inoculated with an agar plug near the midrib and sealed by Parafilm on the plant. Control plants were treated in the same manner with sterile agar plugs. R. officinalis and T. vulgaris plants were flooded up to the collar with deionized water for 24 h. All plants were maintained in a greenhouse at 22°C and watered when needed. All inoculated plants showed root rot or leaf necrosis after 10 days, and control plants remained healthy. The pathogen was reisolated from all infected plant tissues and confirmed as P. nicotianae by molecular methods. P. nicotianae is a cosmopolitan pathogen (CABI 2021) and was found on the given hosts in southern Europe. However, this is its first report in the Czech Republic. Its introduction poses a potential risk for the growth of many ornamental and agricultural plants in the country.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

40106 - Agronomy, plant breeding and plant protection; (Agricultural biotechnology to be 4.4)

Projekt

<a href="/cs/project/SS02030018" target="_blank" >SS02030018: Centrum pro krajinu a biodiverzitu</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů