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First report of Nigrospora sphaerica causing leaf spot of date palm in Pakistan

  • Muhammad Waqar AlamEmail author
  • Abdul Rehman
  • Shahbaz Ahmad
  • Mubeen Sarwar
  • Aamir Nawaz
  • Samiya Mahmood Khan
  • Sajid Ali
  • Sidra Aslam
  • Abdul Mannan
Disease Note

Keywords

Nigrospora sphaerica Leaf spot Pathogenicity 

Date palm (Phoenix dactylifera L.) is one of the most cultivated fruit trees around the world. Pakistan is the 6th largest producer of dates (Mangan et al. 2016). During November 2017, leaf spot symptoms were observed in different date palm orchards. Symptoms included yellow to brown, semicircular to irregular spots (3 mm diameter), which gradually enlarged up to 8 mm diameter and coalesced. Symptomatic tissues of infected leaves were cut into small pieces, surface sterilized in 75% ethanol for 30 s, rinsed three times in sterile distilled water, and cultured onto potato dextrose agar (PDA) for 5–7 days at 25 °C. A purified culture of the isolated pathogen (PD20181) was stored at the Fungal Culture Collection Centre, Department of Plant Pathology, University of Agriculture, Faisalabad. The fungus produced single celled, black, spherical to subspherical conidia (10 to 14 × 18 to 20 μm), borne on a hyaline vesicle at the tip of each conidiophore. Morphologically, the fungus was identified as Nigrospora sphaerica (Sacc.) Mason (Mason 1927; Wang et al. 2017). Identification was confirmed by amplifying and sequencing the ITS region and translation elongation factor 1-alpha (TEF1-α) using primers ITS1/ITS4 (White et al. 1990) and EF1-728F (Carbone and Kohn 1999), respectively. BLAST analysis of GenBank Accession Nos. MH815137 and MK875828 showed 99 and 100% identity with N. sphaerica strains (KX986034 and KY019414) from China. Pathogenicity was verified on 10 detached, surface-sterilized, healthy leaves (cv. Aseel). Leaves were wounded and inoculated with a mycelial plug of 0.5 cm. Leaves inoculated with sterile PDA plug served as negative control. Leaves were placed in a moist chamber at 25 °C and 80% RH. Twelve days post inoculation, inoculated leaves had symptoms similar to those originally observed on affected trees; control remained asymptomatic. The morphological characteristics of the fungi reisolated from inoculated leaves were the same as of original isolates, fulfilling Koch’s postulates. Nigrospora sphaerica has been reported to cause leaf spot of Kinnow mandarin in Pakistan (Alam et al. 2017). To our knowledge, this is the first report of leaf spot caused by N. sphaerica on date palm in Pakistan.

Notes

References

  1. Alam MW, Rehman A, Gleason ML, Riaz K, Saira M, Aslam S, Rosli R, Muhammad S (2017) First report of Nigrospora spaherica causing leaf spot of Kinnow mandarin in Pakistan. J Plant Pathol 107:295Google Scholar
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  4. Mason S.C. (1927). Date culture in Egypt and the Sudan. USDA bulletin no. 1457, Washington, DC, pp. 72Google Scholar
  5. Wang M, Liu F, Crous PW, Cai L (2017) Phylogenetic reassessment of Nigrospora: ubiquitous endophytes, plant and human pathogens. Persoonia 39:118–142CrossRefGoogle Scholar
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Copyright information

© Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2019

Authors and Affiliations

  • Muhammad Waqar Alam
    • 1
    Email author
  • Abdul Rehman
    • 2
  • Shahbaz Ahmad
    • 1
  • Mubeen Sarwar
    • 1
  • Aamir Nawaz
    • 3
  • Samiya Mahmood Khan
    • 4
  • Sajid Ali
    • 3
  • Sidra Aslam
    • 5
  • Abdul Mannan
    • 1
  1. 1.Institute of Agricultural SciencesUniversity of the PunjabLahorePakistan
  2. 2.Department of Plant PathologyUniversity of AgricultureFaisalabadPakistan
  3. 3.Department of Horticulture, Faculty of Agricultural Sciences and TechnologyBahauddin Zakariya UniversityMultanPakistan
  4. 4.Department of Plant Pathology, Faculty of Agricultural Sciences and TechnologyBahauddin Zakariya UniversityMultanPakistan
  5. 5.Department of Ecology, College of Life SciencesBeijing Normal UniversityBeijingChina

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