A novel combination of a new umbravirus, a new satellite RNA and potato leafroll virus causes tobacco bushy top disease in Ethiopia.

Etiological studies of a recently emerged bushy top disease of tobacco in Ethiopia indicated that a ~4.5-kb dsRNA from infected plants represents an umbravirus, whereas a smaller band (~0.5 kb) is that of a new satellite RNA. Potato leafroll virus was also consistently associated with the disease. The three agents, whose experimental host ranges are restricted to members of the family Solanaceae, always occurred together in field samples and are transmitted together by the aphid Myzus persicae nicotianae. The umbravirus, which represents a new species, is most closely related to groundnut rosette virus, and the name Ethiopian tobacco bushy top virus is proposed.

Genetic evaluation of recombinant inbred lines of rice (Oryza sativa L.) for grain zinc concentrations, yield related traits and identification of associated SSR markers.

The objectives of the present study were to evaluate genetic variability parameters, correlations that exist for grain Zn concentration and yield related traits and identification of SSR markers linked to these traits in rice. One hundred seventy six Recombinant Inbred Lines (RILs) of Azucena X Moromutant were grown at University of Agricultural Sciences, Bangalore in augmented experimental design during wet seasons of 2010 and 2011. The study revealed significant genetic variability for all the traits. Grain yield per plant and grain zinc concentration showed higher phenotypic and genotypic co-efficient of variation. Significant positive correlation was observed for grain yield per plant with number of productive tillers per plant (r = 0.5) and number of tillers per plant (r = 0.4). Grain zinc concentration showed negative correlation with grain yield per plant (r = - 0.27). The path-coefficient analysis indicated the positive direct effect of number of productive tillers per plant on grain yield per plant (0.514). Grain zinc concentration showed negative direct effect on grain yield per plant (-0.186). Single-marker analysis using 26 SSR markers on RILs mapping population showed that RM212, RM263, RM6832, RM152, RM21, RM234 and RM3331 had association with grain zinc concentration and other yield related traits. But validation of these markers on fifty two rice genotypes showed that only three markers RM263, RM152 and RM21 had association with grain zinc concentration. Therefore, the genetic information generated and molecular markers identified from this study could be used for zinc biofortification programmes in rice.