Identification of fungal species associated with dieback of tropical fruit trees in Sistan and Baluchestan and Kerman provinces

Document Type : Research Paper

Authors

• Adel Pordel ¹
• Amirreza Amirmijani ²
• Mehi Azadvar ³
• Mousa Najafiniya ⁴

¹ Iranian Research Institute of Plant ProtectionBaluchestan Agricultural and Natural Resources Research and Education Center, AREEO, Iranshahr, Iran

² 2. Department of Plant protection. Faculty of Agriculture, University of Jiroft, Jiroft.

³ Plant Protection Research Department, Kerman Agricultural and Natural Resources Research and Education Center, AREEO, Kerman, Iran

⁴ Plant Diseases Research Department, Iranian Research Institute of Plant Protection, AREEO, Tehran, Iran.

Abstract

Keywords

• Southeast of Iran
• Sampling
• Morphology
• Phylogeny
• Tropical fruits
• Lasiodiplodia
• Neocosmospora

Extended Abstract

Introduction

    The provinces of Sistan and Baluchistan, along with the southern region of Kerman, are recognized as significant areas for producing tropical fruits. The advantageous climatic conditions prevalent in the southern part of the country, particularly in the aforementioned provinces, have contributed to the expansion of cultivated land dedicated to valuable tropical species such as Christ’s thorn jujube (Ziziphus spina-christi L.), Chico (Manilkara zapota L.), and Guava (Psidium guajava L.). In recent years, the provinces of Kerman and Sistan and Baluchestan have reported dieback disease, leading to considerable losses for cultivators. The disease initially manifests in the branches on one side of the trees and progressively spreads, ultimately resulting in the tree's wilting. Given the absence of a comprehensive study addressing the factors contributing to these diseases in the affected regions, the current research aims to isolate and identify the fungi associated with the die-back disease of tropical fruit trees in Sistan and Baluchestan and southern Kerman provinces.

Materials and Methods

During 2022 and 2023, 150 samples were obtained from branches exhibiting die-back symptoms in Christ's thorn jujube, Chico, and Guava trees. Fungal isolation was done using a single spore and hyphal tip method on 2% water agar. These isolates were identified using morphological criteria. Five fungal isolates with distinct morphological characteristics were selected for DNA extraction and nucleotide homology determination. Sequencing of ITS1-5.8S-ITS2 (ITS), and Elongation factor-1α (tef-1α) genomic regions was conducted to confirm the morphological identification.

Results and Discussion

Seventy-one isolates were obtained, with 43 belonging to two fungal genera and 28 being non-spore-producing fungi. Phylogenetic analysis was performed using the Maximum Parsimony method for Lasiodiplodia isolates (ITS and tef-1α gene regions), and Neocosmospora isolates (tef-1α). The identified species in most locations included Neocosmospora solani on Christ’s thorn jujube, Chico, and Guava, and Lasiodiplodia theobromae on Christ’s thorn jujube, which was reported for the first time in Iran.

Conclusion

The study's findings encompass identifying the fungal species Lasiodiplodia theobromae, and Neocosmospora solani exhibiting die-back disease in the Sistan and Baluchestan, and the southern region of Kerman province. Based on our knowledge, the fungal isolates of the hosts of Christ’s thorn jujube, Chico, and Guava in Iran have been reported for the first time. Management strategies to address the drying of tropical fruit trees include ensuring adequate nutrition, preventing water stress, pruning affected branches, and disposing of their remnants. Future research is recommended to assess integrated management approaches tailored to the regional conditions for effectively controlling the die-back disease affecting tropical fruit trees.