Y.W. Khoo, Y. Iftikhar, T. Murugan, N.A. Roslin, R. Adawiyah, L.L. Kong, G. Vadamalai
doi: 10.4454/jpp.v99i1.3848
Citrus are among eight major fruits crops grown in Malaysia, with a total production of 36,450 tons in 2013. Citrus bent leaf viroid (CBLVd, genus Apscaviroid, family Pospiviroidae), is widely distributed in citrus with no specific symptoms associated with its infection but responsible for leaf bending on Etrog citron. Leaf samples of citrus species such as calamondin [Citrofortunella microcarpa (Bunge) Wijnands], kaffir lime (Citrus hystrix DC.), key lime [C. aurantifolia (Cristm.) Swingle], mandarin orange (C. reticulata Blanco), pomelo (C. maxima Merr.), sweet orange [C. sinensis (L.) Osbeck] with stunting, leaf yellowing and epinasty were collected from different states in Malaysia. The rootstocks of these samples were not known. Total nucleic acids were extracted from leaves around the tree canopy and tested by RT-PCR with two sets of primers, CBLV-CM/CBLV-CP (Ashulin et al., 1991) and the newly designed YI4F/YI4R (5’-CGGAGACTTCTTGTGGTTCC-3’ and 5’-CTTGGAAGTCCGCTCGACTA-3’, respectively). Altogether 21 of 133 citrus samples were positive for CBLVd. The resulting amplicons of 328 bp and 234 bp in size were cloned. Sequence analysis revealed 95-99% identity with CBLVd isolate Jp (accession No. AB006734), confirming the presence of CBLVd (KU194472, KX823338-KX823343) in the tested samples. No particular symptoms were observed in the test samples correlated with the presence of CBLVd, thus the observed symptoms may not be induced by this viroid. To the best of our knowledge, this is the first report of CBLVd in Malaysia. Additional investigations on geographical distribution, epidemiology and economic impact are essential to formulate CBLVd management strategies in Malaysia.