Open Access

REVIEW

Citrus Viroids: A New Frontier in Virus and Virus-Like Pathogens in the Citrus Growing Areas

Mustansar Mubeen¹, Yasir Iftikhar^1,*, Ganesan Vadamalai^2,3, Muhammad Aasim⁴, Muhammad Faiq⁵, Uthman Balgith Algopishi⁶, Ahmed Ezzat Ahmed^6,7

1 Department of Plant Pathology, College of Agriculture, University of Sargodha, Sargodha, 40100, Pakistan
2 Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, 43400, Selangor, Malaysia
3 Laboratory of Sustainable Agronomy and Crop Protection, Institute of Plantation Studies, Universiti Putra Malaysia, Serdang, 43400, Selangor, Malaysia
4 Department of Plant Protection, Faculty of Agricultural Sciences and Technology, Sivas University of Science and Technology, Sivas, 58140, Türkiye
5 Department of Plant Pathology, Faculty of Agricultural Sciences, University of the Punjab, Lahore, 54590, Pakistan
6 Department of Biology, College of Science, King Khalid University, Abha, 61413, Saudi Arabia
7 Prince Sultan Bin Abdelaziz for Environmental Research and Natural Resources Sustainability Center, King Khalid University, Abha, 61421, Saudi Arabia

* Corresponding Author: Yasir Iftikhar. Email:

Phyton-International Journal of Experimental Botany 2025, 94(12), 3827-3843. https://doi.org/10.32604/phyton.2025.071555

Received 07 August 2025; Accepted 19 November 2025; Issue published 29 December 2025

Abstract

Citrus viroids are small non-coding RNA pathogens that pose a significant threat to global citrus production by reducing fruit yield, quality, and tree longevity. Several viroids, including Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd), Citrus bent leaf viroid (CBLVd), and newly identified members such as Citrus Viroid VI (CVd-VI) and Citrus Viroid VII (CVd-VII) have been reported from diverse citrus-growing regions. These pathogens are transmitted mainly through vegetative propagation, contaminated tools, and occasionally via seed or pollen, making their management complex. This review synthesizes current knowledge on the biology, structural diversity, transmission, symptomatology, detection, and economic impact of citrus viroids. In addition to compiling existing findings, it emphasizes critical challenges such as understanding host–pathogen molecular interactions, the implications of viroid infections under climate change, and the limited availability of resistant rootstocks. Recent advances in diagnostic tools, including Reverse Transcription Polymerase Chain Reaction (RT-PCR), Quantitative Polymerase Chain Reaction (qPCR), High-throughput sequencing (HTS), and in silico approaches, are evaluated alongside practical constraints in low-resource settings. Furthermore, the review highlights management strategies focused on certified planting material, sanitation, resistant genotypes, and integration into global citrus certification programs. By consolidating existing information while outlining key knowledge gaps and future directions, this work provides a foundation for developing sustainable strategies to mitigate the impact of viroids on the citrus industry.

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Keywords

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