In: Sydowia 75, (2023): 221-232; ISSN 0082-0598, DOI 10.12905/0380.sydowia75-2023-0221, Published online on February 7, 2023

Potential of selected tobacco endophytic fungi against
Sclerotinia sclerotiorum, the causal agent of tobacco
collar rot disease

Mohammad Reza Safari Motlagh1,*, Samar Alavi Rad2, Marwa T. Mohesien3, Monga I. Mossa4, Alireza
Seidavi5, Soumya Ghosh6, Donia H. Sheir7, Kavya Dashora8 & Ahmed M. Abdel-Azeem9,*

1 Plant Pathology Department, Faculty of Agriculture, Rasht Branch, Islamic Azad University, Rasht, Guilan province, Iran
2 Department of Plant Pathology, Master of Plant Pathology, Deylaman Institute for High Education, Lahijan,
Guilan province, Iran
3 Department of Botany and Microbiology, Faculty of Science, Damietta University, New Damietta 34511, Egypt
4 Department of Botany and Microbiology, Faculty of Science, University of Al Arish, North Sinai 45516, Egypt
5 Faculty of Agriculture, Rasht Branch, Islamic Azad University, Rasht 4147654919, Iran
6 Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State,
Bloemfontein, 9301, South Africa
7 Chemistry of Natural Products Department, National Research Center, Giza 12622, Egypt
8 Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, India
9 Department of Botany and Microbiology, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt

* e-mails: ssafarimotlagh@yahoo.com, ahmed_abdelazeem@science.suez.edu.eg

Motlagh M.R.S., Rad S.A., Mohesien M.T., Mossa M.I., Seidavi A., Ghosh S., Sheir D.H., Dashora K. & Abdel-Azeem A.M.
(2023) Potential of selected tobacco endophytic fungi against Sclerotinia sclerotiorum, the causal agent of tobacco collar rot
disease. – Sydowia 75: 221–232.
Tobacco collar rot (TCR) disease is caused by the fungus Sclerotinia sclerotiorum, which is able to infect over 300 different
types of plants, including common weeds. S. sclerotiorum is one of the most important pathogens of tobacco reported from all
tobacco cultivating regions of the world. Controlling this disease by chemical and cultural methods seems highly difficult and
using resistant cultivars has not been sufficient. Endophytic taxa hosted by Nicotiana tabacum were evaluated against pathogenic
S. sclerotiorum isolates in vitro and in greenhouse. Based on phenotypic identification, five endophytic taxa were identified
as Trichoderma harzianum, T. virens, Curvularia australiensis, Aureobasidium pullulans and Geotrichum candidum respectively.
These isolates exhibiting inhibitory effects against S. sclerotiorum were cultivated in vitro on PDA plates and the percent of inhibition
was calculated. T. harzianum came first by showing the highest percentage of inhibition against S. sclerotiorum followed
by T. virens, C. australiensis, A. pullulans and G. candidum. In growth chamber experiments, all taxa were able to reduce TCR
disease rating. C. australiensis was deemed the most effective for reducing disease rating up to 2.6 (23.75 %) followed by A. pullulans,
G. candidum, T. virens and T. harzianum respectively. In greenhouse studies, T. virens increased the height, fresh and dry
weight of the plant shoots in the presence of TCR which reflects the stimulating properties of T. virens in the growth of shoot
organs of tobacco plants. Microscopic examination showed that all endophytic taxa have a positive tropism and anastomosis
toward S. sclerotiorum. Overall, the antagonistic endophytic fungus C. australiensis is recommended as an effective biocontrol
agent for S. sclerotiorum wilt management in tobacco plants. We recommend further research on this taxon in order to develop
an industrial eco-green biostimulant against TCR disease.

Key words: Bioprospecting, biotechnological potential, fungi, Nicotiana tabacum, Sclerotinia spp