True seed transmission of Sugarcane bacilliform virus

Abstract

Sugarcane (Saccharum spp hybrids) is a major commercial crop grown in tropical and subtropical regions of the country. Like any other crop, biotic stresses are a major constraint to sugarcane production and of these; fungal and viral diseases are causing economically significant losses worldwide. Among various viral diseases causing major destruction, leaf fleck caused by Sugarcane bacilliform virus (SCBV) is one of the emerging threats which affects global exchange of sugarcane germplasm. In sugarcane varietal development, parents of interest are crossed and true seed or “fluff” are obtained to develop new varieties. SCBV occurs throughout the country in the new varieties and such widespread occurrence was suspected due to true seed transmission of SCBV. However, until now, no experimental evidence has corroborated these observations. In this study we have undertaken to establish possible transmission of the virus from sugarcane parents to their progenies. Eight and three month old progenies from 18 crosses and their parents were tested through PCR assays for the presence of the virus. All the tested parents were found to be positive to the virus infection. About 50 to 100% of the progenies were positive to SCBV in PCR assays. Real time PCR assays of three month old progenies along with their parents revealed that all the samples were positive to the virus. Fluff samples of the parents Co 0238 and Co 11015 commonly used in hybridization were also tested positive for the virus. Even though viral titre is comparatively low in the fluff samples it could be concluded that true seed acquires the virus from the parents and has a role in disease transmission. Probable seed transmission may be attributed to the rampant occurrence of the leaf fleck under field conditions in the country.