Incidence, geographical distribution and genetic diversity of sugarcane striate virus in Saccharum species in China.

Abstract

A novel virus of the genus Mastrevirus, family Geminivirdae, was recently reported in sugarcane germplasm collections in Florida, Guadeloupe and Réunion, and was named sugarcane striate virus (SStrV). Although the full-length sequence of a SStrV isolate from China was obtained in 2015, the incidence, geographical distribution, and genetic diversity of this virus remained unclear. A single leaf sample from 2,368 sugarcane plants from main sugarcane producing regions of China and germplasm collections were tested for SStrV by polymerase chain reaction (PCR). Average virus incidence was 25.1% for field collected samples and SStrV was detected in most Saccharum species and two sugarcane-related species with the highest incidence in S. officinarum (44.1%) followed by Saccharum spp. local varieties (33.3%) grown for chewing cane for a long time. The virus incidence was much lower (6.8%) in modern commercial cultivars (Saccharum spp. hybrids). Phylogenetic trees based on full-length genomes of 157 SStrV isolates revealed that Chinese isolates comprised strains A and B, but not C and D that were reported in Florida, USA. SStrV strain A was the most prominent (98.7%) and widespread strain in China and was further divided into eight sub-groups. Almost half (45.6%) of the SStrV-positive samples from S. officinarum and Saccharum spp. local varieties were co-infected with sugarcane mosaic disease viruses or sugarcane yellow leaf virus. Interestingly, most of the plants infected by strain A of SStrV were asymptomatic. SStrV appears to be widespread in China, and its influence on chewing cane deserves further investigation.