Morphology Characterization, Molecular Identification, and Pathogenicity of Fungal Pathogen Causing Kaffir Lime Leaf Blight in Northern Thailand.

Nakarin Suwannarach,Surapong Khuna,Ratchadawan Cheewangkoon,Saisamorn Lumyong,Jaturong Kumla,Piyawan Suttiprapan

doi:10.3390/plants11030273

Nakarin Suwannarach, Surapong Khuna + Show 4 more

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https://doi.org/10.3390/plants11030273

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Abstract

Thailand is known to be the largest producer of kaffir lime leaf products in the global market. In 2021, leaf blight was found on kaffir lime plants (Citrus hystrix DC.) in Lamphun Province of northern Thailand. This disease has been associated with significant economic losses. However, there have been no prior reports of leaf blight on kaffir lime plants in Thailand or anywhere else in the world. In this study, causal fungi were isolated from lesions of kaffir lime plants and a total of three fungal isolates were obtained. All causal fungi were identified as Lasiodiplodia chinensis based on morphological characteristics and the phylogenetic analysis of combined sequences of the internal transcribed spacer (ITS) of ribosomal DNA, the translation elongation factor 1-alpha (tef-1), β-tubulin (tub), and RNA polymerase II subunit (rbp2) genes. Pathogenicity tests were conducted and the results revealed that all isolated fungi caused symptoms of leaf blight on inoculated leaves. This outcome was similar to symptoms that naturally occur and have been observed in the field. This is the first report on kaffir lime leaf blight caused by L. chinensis. Our study will provide information of high value for the development of effective strategies for the monitoring and prevention of this disease.

Highlights

Kaffir lime (Citrus hystrix DC.) is a citrus plant that is native to tropical Asia
Samples of leaf blight of the kaffir lime plant (C. hystrix) were collected from one plantation area located in Lumphun Province, northern Thailand
Three isolates of L. chinensis were isolated from the lesions of leaf blight on kaffir lime plants collected from northern Thailand

Summary

Introduction

Kaffir lime (Citrus hystrix DC.) is a citrus plant that is native to tropical Asia. This plant is commonly cultivated in tropical regions, especially Southeast Asia (Laos, Indonesia, Malaysia, Thailand, and Vietnam) [1,2,3]. Kaffir lime leaves and fruits have been beneficially used in traditional medicine to treat certain common ailments such as colds, congestion, and coughs [6,7,8]. They have served as a digestive stimulant that can alleviate flatulence and indigestion, act as a blood purifier, and reduce high blood pressure [7,9]. The essential oils of kaffir lime leaves and fruits have been reported to display various bioactivities. Thailand is known to be the largest producer of kaffir lime leaf products in the global market, followed by Indonesia, Malaysia, and India [5]

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