Virus indexing for Sugarcane Yellow Leaf Virus (SCYLV) in field varieties and in vitro regenerated plantlets of sugarcane

Abstract

Yellow leaf (YL) of sugarcane caused by Sugarcane yellow leaf virus (SCYLV) is a serious disease affecting production and productivity in many ruling sugarcane varieties in India, especially in coastal region of Andhra Pradesh state, causing losses ranging from 60% in the first crop to 100% in the ratoon crop. During 2013–2015 seasons SCYLV indexation of meristem tip culture derived sugarcane plantlets as well as usual seed canes planted field varieties was carried out using DAS-ELISA and RT-PCR at RARS, Anakapalle, India. Both leaf extracts and stem sap samples were used. Sixteen samples out of 20 were positive to DAS-ELISA SCYLV diagnosis with OD 405 values of 0.707 to 1.788, while only 13 samples had the visible disease symptoms out of the 20 samples comprising 13 different varieties. This proved efficacy of DAS-ELISAfor indexing even asymptomatic YL infected sugarcane plants. RT-PCR test also detected the virus in both symptomatic and asymptomatic plants. The detection efficiency was considerably good with samples obtained from the same plant (both stem sap and leaf extract) either with colour change or with OD 405 values proving effective and quick indexing using DAS-ELISA. Further, RT-PCR can be used as a confirmatory test to determine the sensitivity of ELISA. In case of in vitro regenerated sugarcane plantlets, all the samples, both hardening stage plantlets and field grown meristem tip culture derived plants didn’t showed any positive reaction for the virus daignosed by DAS-ELISA with lower OD 405 values of 0.082 to 0.0321compared to disease free field varieties (OD 405 from 0.151 to 0.355) making it as best management option with proper indexing.