Detection of Citrus Bent Leaf Viroid in Citrus Orchards of Sargodha, Pakistan

Abstract

A study was conducted to monitor the Citrus bent leaf viroid (CBLVd) in citrus growing areas of district Sargodha, Pakistan during 2017-2018. Collected samples were tested by RT-PCR using specific primers. PCR positive samples were used to confirm the CBLVd incidence and severity on different citrus varieties grown at different regions of Sargodha. Maximum disease incidence was recorded in Kot Momin with the mean value of 24%, with severe symptoms of bark cracking, backward leaf bent and stunting. Minimum disease incidence was recorded in in Sillanwali region with the mean value of 3.33%. The symptoms in Sillanwali were only yellowing and slight leaf bent. Maximum severity was observed in Kot momin (0.60%). Molecular detection of CBLVd by RT-PCR confirmed the diagnosis of the viroid. This survey was carried out for the first time in Sargodha district to monitor the occurrence of citrus bent leaf viroid following the first report of its detection in Pakistan in 2009. Since many declining citrus trees were found negative to CBLVd testing, other causal agents can be involved, and extensive surveys are still required in the near future. Keywords: Citrus, RT-PCR, CBLVd, Disease incidence, viroid, Sargodha, Pakistan