Abstract:
Citrus refers to a group of trees and shrubs belonging to the Rutaceae family, which is
rich in nutrients and bioactive compounds. Some economically important citrus
species are grown in various regions in Sri Lanka. Viral and viroid diseases are the
major challenges for citrus production in Sri Lanka. Information on citrus viruses and
viroids is scanty and outdated in Sri Lanka. No proper survey has been carried out to
identify the different viruses present. This study aims to identify the viral and viroid
diseases associated with citrus cultivations and chatacteize the viruses associated
with citrus cultivations in Kurunegala district, Sri Lanka. For the detection of viral
and viroid diseases, symptomatic leaf samples exhibiting symptoms of yellowing, leaf
curling, vein clearing and stunted growth were tested by serological and molecular
based techniques. Triple Antibody Sandwich ELISA (Compound ELISA) was
performed for the detection of Cinus tristeza virus (CTY) and 76 positive samples
were detected out of 100 samples in Kurunegala district. Furthermore, their identity
was confirmed by RT-PCR using specific primers (CTV -ARl8F and CTV -AR18R)
and expected band size at 51 1 bp. Molecular detection by RT- PCR was conducted for
detection of Citrus tristeza virus (CTY), Citrus vein enation virus (CVEV), Cinus
yellow mosaic virus (CYMY), Citrus yellow vein clearing virus (CWCV), Cinus
bent leaf viroid (CBLYd), Hop stunt viroid (HSVd), and Citrus viroid 1(CVd I LSS).
Presence of the CTV was confirmed and amplified PCR products of CBLVd, and
CVd I LSS were obtained for further confirmation. For the molecular charactertzation
of viral and viroid diseases, Citrus tristezs vlrzs sequence was confirmed with 99% of
sequence identity over 464 base pairs and phylogenetic analysis reveatred genetic
variations among the Citrus tristeza virus pIS gene sequences and Citrus vein enation
virus. These findings demonstrated the urgent need for continuous surveillance and
effective disease management strategies to mitigate the impact of viral and viroid
infections on citrus crops. Furthermore, the study offered crucial insight into the
molecular detection of citrus pathogens in Kurunegala district to contribute to the
development of sustainable disease control strategies for enhancing citrus
productivity.
