method of s )read, and some of the Jhysical Jro >erties. mosaic virus resulted from the nresence of a mixture
1 1 . 1 l 1
To Yet such information inoculations were made from of strains of virus, or from the Jresence of differently
k g p E 1 .
A more than a hundred representative naturally infected reacting plants within a population of a variety of red
-¢ v plants to several hosts, including beans, peas, tobacco, clover plants. Pied clover is cross pollinated, and in-
crimson clover, and red clover. On the basis of host diyidual Jlants are known to differ amon r themselves
vid 1
H ran re, s m atoms method of transmission and the with res Ject to susce Jtibilitv to some diseases, as well ‘
_< 1 3 ’ 1 1 . _
»*»‘ presence of characteristic crystalline bodies inside as in appearance. It was felt that inoculation of `
’ __ _; nuclei of some infected cells, it was concluded that clonally propagated plants might help to resolve this
. the virus isolated most commonl from naturally in- nroblem. Therefore, cuttin YS were made from selected
. 1
°·»" fected red clover is ellow bean mosaic. For instance healthy Jlants of Kenland red clover; then several
Y . 1
V in one series of isolations this virus was recovered plants of each clone were inoculated with one strain
from 113 of 136 naturally infected red clover plants of the virus. The results were quite striking: symptoms ,
* showing virus symptoms. In the same test yellow on all plants of any one clone were the same, but
_r v_ bean mosaic virus was also recovered from 32 of 35 symptoms on different clones were different. Of 126
naturally infected sweet clover nlants, and from 25 of clones tested 8 failed to develo > sym utoms; 95 showed
. 1 » 1 .
~`* 31 crimson clover plants. either vein yellowing or mosaic, some mild, some `
n . severe and some intermedi·1te· 1() showed both vein r
v‘* Several Hundred Seedlings lnoculcted ’_ ` . ,( ’ _
. _ . yellowmr and death of veins; and 13 were actually
. . . , Z;. .
After it was found that yellow bean mosaic virus is . . _
Y* _ _ . _ killed. Symptoms on selected representative clones
commonly present in naturally infected plants 1t .
__ _ , ‘ _ _ are shown lll the photographs.
c *1 seemed desirable to find out whether this virus would ~ . _ .
_ _ _ _ The results of these tests show quite cleanly that m
_ cause similar symptoms in inoculated plants. Ac- . . _ ._ _ -
·v* . _ Kentucky yellow bean mosaic virus is the cause of
cordingly, several hundred red clover seedlings were ~ . . ~ .
_ _ _ _ _ much of the virus infection on red clover, and that a
"’ inoculated by rubbing leaves with a typical strain of . · _ .
t ' , , wide range of symptoms such as occurs in naturally
· yellow bean IHOSEIIC V1l`llS that had been recovered . . . .
‘i*` 2 , infected red clover plants can be induced in a popula-
from red clover. As these inoculated plants became . ~ . .... .l
_ . _ _ . tion of plants, within a variety, by inoculation witi
Y 1llf€‘Ct€(l it was obvious that the range of symptoms (me Culture Of Veuow bein mosqic Virus
f was similar to the sym toms yresent in fields of ~ ' .. . -
* " ( . » ‘ P f _ The fact that such different symptoms, ranging from
· naturally infected red clover plants. But it was not . ~
{QQ. ‘ _ . mild mottle to death of plants, can be produced by
~. yet clear whether such different symptoms produced
_ f_ - by inoculation with one Held isolate of yellow bean ((;(,,,,;,,,,U([ ,,,, ;>(,_qy3)
iw `   ;; ;
- I J" . . . B c
 ls. ` , . 3 if V, ' ' " "
Ft, * .
RCS' 4 f 1 U ‘ l Fig. 2.- A healthy
1,: I3 V ‘ ‘ ' Q _ I? leal is shown in
R! f   V l . ' x I A. The range ol`
jh A __ - ‘ · ‘ symptoms pro-
  _ ·· _ V, ` duced by inocu-
· *···.._ 5 ‘ V ‘ . . Z .
4   ..___ ,`,,¢-; f ‘ " _ ” latmg different m·
_   · F tliutlual plants ol
,3e _ E · _ . p red clover with
V - . _ thc saznc culture
fl-   4 · ‘ V of yellow bean mo-
" _ tl   ‘ _ r saic virus is shown
c _, · - in li through l.
' , . ’ ‘ tl’|att· t·ottrtt·sy l’h)lo·
    . vv pntholot;) ) K
at `tf `· _ A _-p I   ` h _   ` W   fi 7  
~»: 1 ‘ ~, , _ , __,._ * ‘_ ‘ _ i _,,_,     `·   _ _