Open AccessDetection and Molecular Characterization of ‘Candidatus Liberibacter asiaticus’ and Citrus Tristeza Virus Associated with Citrus Decline in Bhutan
Author(s) -
Dilip K. Ghosh,
Amol Kokane,
Sunil Kokane,
Jigme Tenzin,
Mrugendra Gubyad,
Phuntsho Wangdi,
Ashutosh A. Murkute,
Ashwani Sharma,
Siddarame Gowda
Publication year - 2021
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto-07-20-0266-r
Subject(s) - biology , citrus tristeza virus , rutaceae , genotype , horticulture , vigna , crop , locus (genetics) , diaphorina citri , veterinary medicine , plant virus , botany , gene , virus , virology , agronomy , genetics , medicine , hemiptera
Citrus, mainly mandarin (Citrus reticulata Blanco), is an economically important fruit crop in Bhutan. Despite having favorable agroclimatic conditions for citrus cultivation, the early decline of fruit-bearing orchards coupled with low crop productivity is a major concern among citrus growers. During a recent survey, an association of ‘Candidatus Liberibacter asiaticus’ (citrus greening) and citrus tristeza virus (CTV), either singly or as mixed infections in declined citrus trees, was recorded in all four major citrus-growing districts (Tsirang, Dagana, Zhemgang, and Sarpang). Using PCR-based diagnosis, a higher incidence of citrus greening (27.45%) and tristeza (70.58%) was observed in symptomatic field samples. Detection and characterization of ‘Ca. L. asiaticus’ was performed based on the 16S ribosomal DNA, prophage gene, 50S ribosomal rplA-rplJ gene, and tandem repeats of the CLIBASIA_01645 locus. Similarly, the coat protein, p23, and p18 genes were used as genetic markers for the detection and characterization of Bhutanese CTV. The ‘Ca. L. asiaticus’ isolates from Bhutan segregated into classes II and III based on the CLIBASIA_01645 locus, analogous to Indian isolates from the northeast region and Term-A based on the CLIBASIA_05610 locus. CTV isolates of Bhutan were observed as closely related to the VT strain, which is considered to be the most devastating. To the best of our knowledge, this is the first study on molecular characterization of ‘Ca. L. asiaticus’ and CTV isolates and their association with citrus decline in Bhutan.