The Occurrence and Genetic Variability of Tea Plant Necrotic Ring Blotch Virus in Fujian Province, China

Abstract

Tea plant necrotic ring blotch virus (TPNRBV) is a kitavirus that poses a serious threat to the cultivation of tea, one of the most economically important plants in many Asian countries. However, the occurrence and genetic variability of this virus remain poorly understood. This study investigated the occurrence of TPNRBV in Fujian Province, China, one of the largest tea producers in the country, and determined the complete genome of 10 new TPNRBV isolates. The results revealed that TPNRBV is widespread in Fujian. The nucleotide diversity values for the RNA1-4 segments of TPNRBV were found to be 0.027, 0.016, 0.027, and 0.014, respectively. Among the seven proteins of TPNRBV, P22 was the least conserved, while MP was the most conserved. The 5′ termini of the genomic segments of TPNRBV commonly possessed a sequence of 5′-AATTACGA-3′ (RNA1-3) or 5′-ATTAACGA-3′ (RNA4). Furthermore, the 3′ non-coding region of TPNRBV RNA4 exhibited significant length variation due to frequent deletion/insertion mutations. Recombination and purifying selection likely played important roles in shaping the genetic structure of TPNRBV. These findings provide a snapshot of the epidemiology and genetic structure of TPNRBV, offering valuable information for the development of targeted strategies to control and manage TPNRBV in tea cultivation.