Abstract
Pinus thunbergii Parl., known as black pine, is widely distributed all over China. This pine variety can prevent soil desertification and promote soil conservation and is excellent for constructing fast-growing forests and shelter belts. The timber of this species can be used for infrastructure construction and furniture production. In August 2020, needle blight symptoms were found on several trees of black pine in Sichuan Province, China. Further surveys showed that these symptoms are common while the disease incidence is less than 30% which indicated the severity of the disease is mild. The tips of old needles first turn grayish green and developed into brown bands ranging from 1 to 2 mm. To determine the pathogen, 20 needle samples with typical symptoms were disinfected with 75% alcohol, and sections of the tissue were cut from joints of diseased and healthy tissues (visually healthy) with a sterilized scalpel, surface sterilized for 45 seconds in 75% alcohol, soaked for 90 seconds in 1.5% NaCIO, rinsed in sterilized water and dried. Small cut tissues were placed on potato dextrose agar (PDA) at 25℃ for 10 days. Pure cultures were obtained by monosporic isolation. The colonies initially appeared white to cream, yeast-like, and later turned to pink and remained at least 10 days. Conidia were hyaline, smooth-walled, single-celled, and ellipsoidal with variable shape and size, 7.5 to 16 × 3.5 to 7 µm (Zalar et al. 2008). DNA was extracted from the mycelium of the isolate by the cetyltriethylammonium bromide (CTAB) method and amplified through polymerase chain reaction (PCR) with the internal transcribed spacer (ITS) region of rDNA and partial β-tubulin genes of a representative isolate (SC05) were amplified using the ITS1/ITS4 and Bt2a/Bt2b primer pairs, respectively(Wu et al. 2017). The sequences submitted to GenBank (Accession Nos. MW228368 for ITS and MW256762 for β-tubulin) showed high similarity with BLAST sequences of Aureobasidium pullulans (ITS, KR704881 [100%]; β-tubulin, MT671934 [99.49%]). For the pathogenicity test, a conidial suspension was prepared with a concentration of 2.0 × 107 conidia/ml. The suspension was sprayed onto 3 annual seedlings' needles, and the control was sprayed with sterile water. Inoculated and non-inoculated plants were kept in humid chambers in a glasshouse. After 10 days, typical symptoms appeared on inoculated needles, whereas control needles remained symptomless. The fungus, A. pullulans, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Aureobasidium pullulans, a ubiquitous saprophytic fungus on many fruits and very rarely reported to cause disease on pine needles. Only reported invasion of Ozone-injured needles in P. strobus (Costonis and Sinclair 1972) and needles damaged by acid rain in P. sylvestris (Ranta 1990). To our knowledge, this is the first report of brown spot needle blight on P. thunbergii caused by A. pullulans in China. The disease represents a threat to pine manufactures and more research on the pathogenesis and management is needed. .
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Claims 8
Claim · model-written summary
Aureobasidium pullulans was reported as the cause of brown spot needle blight on Pinus thunbergii in China, a first report.
- Taxon
- P. thunbergii
Pinus thunbergiie1 - Interactor
- A. pullulans
Aureobasidium pullulanse1pathogen - Outcome
- brown spot needle blighte1
- Setting
- in Chinae1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“this is the first report of brown spot needle blight on P. thunbergii caused by A. pullulans in China”
Claim · model-written summary
The needle blight incidence in surveyed pine was less than 30%, indicating mild severity.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Outcome
- disease incidencee2
- Value
- less than 30%e2
- Qualifier
- the severity of the disease is milde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e2“the disease incidence is less than 30% which indicated the severity of the disease is mild”
Claim · model-written summary
The fungal colonies appeared white to cream and yeast-like on PDA.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Outcome
- coloniese3
- Qualifier
- white to cream, yeast-likee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e3“The colonies initially appeared white to cream, yeast-like, and later turned to pink and remained at least 10 days”
Claim · model-written summary
Conidia were hyaline, smooth-walled, single-celled and ellipsoidal, 7.5 to 16 × 3.5 to 7 µm.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Outcome
- Conidiae4
- Value
- 7.5 to 16 × 3.5 to 7 µme4
- Qualifier
- hyaline, smooth-walled, single-celled, and ellipsoidale4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e4“Conidia were hyaline, smooth-walled, single-celled, and ellipsoidal with variable shape and size, 7.5 to 16 × 3.5 to 7 µm”
Claim · model-written summary
ITS sequences of the isolate showed 100% similarity with Aureobasidium pullulans in BLAST.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Outcome
- high similarity with BLAST sequences of Aureobasidium pullulanse5
- Value
- 100%e5
- Qualifier
- ITS, KR704881e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e5“showed high similarity with BLAST sequences of Aureobasidium pullulans (ITS, KR704881 [100%]; β-tubulin, MT671934 [99.49%])”
Claim · model-written summary
Beta-tubulin sequences of the isolate showed 99.49% similarity with Aureobasidium pullulans in BLAST.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Outcome
- high similarity with BLAST sequences of Aureobasidium pullulanse5
- Value
- 99.49%e5
- Qualifier
- β-tubulin, MT671934e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e5“showed high similarity with BLAST sequences of Aureobasidium pullulans (ITS, KR704881 [100%]; β-tubulin, MT671934 [99.49%])”
Claim · model-written summary
Inoculated pine needles developed typical symptoms, whereas control needles remained symptomless.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Treatment
- inoculatede6
- Interactor
- Aureobasidium pullulansAureobasidium pullulanst0pathogen
- Outcome
- typical symptomse6
- Comparator
- control needlese6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e6“typical symptoms appeared on inoculated needles, whereas control needles remained symptomless”
Claim · model-written summary
Aureobasidium pullulans was reisolated from the lesions, confirming Koch's postulates.
- Taxon
- Pinus thunbergiiPinus thunbergiit0
- Interactor
- A. pullulansAureobasidium pullulanse7pathogen
- Outcome
- was reisolated from those lesionse7
- Qualifier
- confirming Koch's postulatese7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Brown Spot Needle Blight on Pinus thunbergii Caused by Aureobasidium pullulans”
e7“The fungus, A. pullulans, was reisolated from those lesions, confirming Koch's postulates”