Studies on the Indicator Plants for Citrus Viruses

V. Retransmission of the causal virus of Satsuma dwarf from herbaceous host to citrus

Abstract

The virus which transmitted mechanically from Satsuma dwarf tree to herbaceous plants was used for retransmission. Inoculation was made by injection. The retransmission occurred from infected kidney bean to the four of the five seedlings of Satsuma mandarin and three of the eight of Natsudaidai. When the RNA specimen of this virus prepared from sap of infected kidney bean by the treatment of phenol was used for retransmission, four of the thirty seedlings of rough lemon were infected.
In the seedlings retransmitted with this virus, the flecking and line pattern were produced on the new growth of Satsuma mandarin made following infection, chlorotic ring or spot on rough lemon and flecking and mottle on Poncirus trifoliata. The warping of young leaves and downward boat or spoon shape of mature leaves which are typical symptoms of Satsuma dwarf appeared on the shoots of Satsuma mandarin grown secondary after cutting. On the basis of these evidence, it was confirmed that this mechanically transmissible virus is the causal virus of Satsuma dwarf.
In Satsuma seedlings inoculated with Satsuma dwarf virus, characteristic flecking and line pattern developed on the several shoots which sprouted on the same side of stem as inoculated points and from these shoots the causal virus was detected. All of the shoots grown secondary after cutting of first growth showed symptoms and positive reaction on detecting test of causal virus.