BIOLOGIA PLANTARUM (PRAt tA)

1 (2) : 113--122, 1959

A New Strain of Tobacco Mosaic Virus Caused by Influencin 9 the Metabolism of the Host

J A R M I L A SVOBODOV/(

Depar tmen t of P lant Pathology, Ins t i tu te of Biology, Czechoslovak Academy of Sciences, P raha

Received September 11, 1958

Souhrn

V prAci je popsfixl nov3~ kmen viru tabAkov~ mosaiky, kter3~ podle svI~ch charak- teristick:~ch pAskov:~ch p~iznakfl (,,Stripe", ,,Streifen") byl nazvAn S-kmenem VTM. Jako v3~choziho materiAlu bylo pou~ito Al-kmene viru tabAkov~ mosaiky.

Na rozdil od metod a~ dosud pou~ivan3~ch byl S-kmen zlskAn pHm3hn zAsahem do metabol ismu hostitelsk6 rostliny, p~ivod~n:~m zm~nou jejlho ~ivotnlho prost~edi. (SvoBoDov~_ 1954, 1958). Bylo pou~.ito obvykl:~ch hostitelfl viru tabAkov~ mosaiky, p~edev~im rostlin tabAku a rajSat. Tyro rostl iny byly vyp~stovAny za aseptick:~ch podminek na agarov:~ch pfldAch v Erlenmeyerov~ch bafikAch p~i sni~eni d&vek ~ivin, za zkrAcen6ho sv~teln6ho dne a p~i omezen~ v:~mi~nit vzduehu, tak~e za- krsly. Po pasA~i v~ehozlho kraene VTIV[ (Al-kmene) t6mito zakrsl3~mi rostl inami do~lo ke zmSnAm p~iznakfl, kter~ se projevily teprve v dal~ich pasA~ich na rostli- nAch vyp~stovan37ch za normAlnich podminek ve sklenlku v zahradnl pfld~, kde m~l virus zase normAlni mo~nost se mno~it. Z dosa~en~ch p~iznakfl byla dale sle- dovAna jen zm~na nejv:~razn~j~i (pAskov~ p~iznaky S-kmene). Timto st~idav~m pasA~ovAnlm Al-kmene VTM rostl inami normAlnlmi a zakrsl:~mi, p~stovan3~mi v um816m ~ivn6m prost~edi, tj. dvoj- nebo i trojnAsobnou nAhlou zm6nou ~ivot- niho prost~edl viru, byl zlskAn nov3~ kmen (S-kmen) celkem p6tkrht v rflzn3~eh roSnich dobhch. Po strAnce symptomatick8 nebyly zji~tSny mezi jednotliv3~mi reprodukcemi t~to zmSny rozdily. V3~sledky byly tak~ stejn6, poehAzel-li v~r- chozi material z rostl in raj6at nebo z tabAkfl odrfldy Samsun.

Na vznik nov6ho kmene nepflsobila jen zakrslost hostitelsk:~ch rostli~, jak ukA- zaly pasA~e viru zakrsl:~mi rostl inami na mikrozAhonu ve voln~m prost~edl, ale bylo t~eba ovlivn~ni metabol ismu abnormAlnim prost~edlm v Erlenmeyerov~ baflce jehti$ po o6kovAnL

Po zp~tn~eh pasA~ich S-kmene z rostli~, vyp~stovan3~ch b~n:~m zpflsobem ve skleniku, na rostl iny se zakrsl3hn rflstem v um~l~m ~ivn~m prost~edi k dalw zm~nAm nedo~lo. Tak8 pasA~e na deseti jir~3~ch hostitelich p~stovan3~ch b ~ n ~ m zpflsobem v zahradni pfld~ i v umSl~m ~ivn~m prost~edi ~Adzxou dalai zm~nu p~i- znaku nep~ivodfly. S-kmen je udr~ovAr~ stAl:~mi pasA~emi na Nicotiana tabacum Samsun po dobu ~esti let, p~i6em~ ka~doroSn8 dochAzl k hromadn~mu oSkovAnl na velk~ po6et rostlin. Pova~ujeme tedy dosa~enou zm~nu za trvalou.

113

114 J. SVOBODOV~

Ko vzniku nov6ho kmene postaSilo nep~im6 ovlivn~nl viru prost~ednietvim pozm~rt~n6ho metabolismu hostitelsk6 rostliny. Zm~ina se projevila a~ po pash~i normhlnlmi, ni jak neovlivn~n~mi rostlinami, kdy reprodukeo v i m nebyla u~, ome- zov~na zpornalen3hn r f s tom hostitelsk6 rostliny. Jo ur6ith analogie vo vzniku S-kmene a TM 44, ziska~6ho PFA~CCHUCaEM a spol. (1940). TM 44 vznikl pfisobenim X-paprskfi; jeho v~ehozim materis byl v~ak oby6ojnp zelen~r kmen tabhkov6 mosaiky. Nenl ~ehena ot~zka, zda S-kmen vznikl selokel hobo mutael, i~utaei v~ak pova~ujerne za pravdifpodobn~jw

Zji~tt~nl biologiek~reh, chemiekpeh a dal~ieh vlastnosti S-kmene a jejich srovnhni s vlas tnostmi jeho kmene v22chozlho a obySejn6ho zelen6ho kmeno VTM bude publikov~no.

Summary

The paper describes a new strain of tobacco mosaic virus which has been named S-strain of TMV because of its characteristic stripe symptoms. The Al-strain of tobacco mosaic virus was used as the initial material.

In contrast to methods used hitherto the S-strain was obtained by interfering with the metabolism of the host plant by a change in the environment. ( S V O B O D O V ~ 1954, 1958). The usual hosts of tobacco mosaic virus were used, chiefly tobacco and tomato plants. These plants were cultivated under aseptic conditions on an agar medium in Erlenmeyer flasks with a reduced amount of nutrients, a shortened period of illumination and a limited air supply, so tha t they were stunted. Following the passage of the initial Al-strain of TMV through these dwarfed plants changes in symptoms appeared, which became apparent only after further passages through plar~ts grown under normal conditions in a glass house in garden soil, where the virus once again had normal conditions for reproduction. Of the new symptoms obtained, only the most striking were further studied (the symptoms of S-strain). By means of alternating of the passage of the Al-strain of TMV from normal to dwarfed--to normal plants grown under artificial nutrient conditions, i. e. a twice or thrice repeated sudden change of environment, the new strain (S-strain) was obtained five times in all and at different times of the year. From the symptomatic point of view no differences were found in the different repetitions of this change. The results were also the same for material from tomato plants and from tobacco of the Samsun variety.

The origin of the new strain was not caused only by the stuntedness of the host plants. I t was also necessary to influence its metabolism by an abnormal environment (particularly insufficient air) in the Erlenmeyer flask before and after inoculation.

Following the reverse passage of the S-strain from plants grown normally in a glass house to dwarfed plants in an artificial environment no further changes occurred. Neither did the passage to ten other hosts grown normally on garden soil and in artificial nutrient produce any further change in symp- toms. The S-strain has been maintained by a succession of continuous passages through Nicotiana tabacum Samsun for six years, and each year mass inocu- lation of a large number of plants is carried out. We therefore now consider the change to be permanent.

A N E W S T R A I N OF TOBACCO MOSAIC V I R U S 115

Indirect influencing of the virus through a change in the metabolism of the host plant sufficed for the induction of the new strain. I ts symptoms appeared only after passage through normal unaffected plants, where the virus repro- duction was not inhibited by the retarded growth of the host plant. There is a certain similarity in the emergence of the S-strain and the TM44-strain, obtained by PFANCHUCH et al., with X-ray irradiation. However, the initial material was the ordinary green strain of TMV.

The biological, chemical and other characteristics ascertained for S-strain and a comparison of these with the characteristics of the initial M-strain and the ordinary green strain of TMV will be published later.

Introduetion

For the development of the large number of new strains obtained in the laboratory the effect of raised temperatures on the infected plant or insect vector (KuNKEL 1937), passage through the host plant on which the virus usually parasitises and the effect of radiation were all used. L ~ s o N et al. (1955) achieved mutat ion by the action of nitrogen mustard. Sux~ov (1955) describes new strains which developed following infection of the host plants by various strains and species of virus (Su•Rov and KAPITSA 1956). The greatest number of strains was isolated by mechanical separation from a mix- ture of strains, by selection of inoculum from different parts of the leaves and from different spots. There has been no success in obtaining new strains by influencing the virus itself outside the host cell, although various chemical reagents and other agents were tried. Only .the re-combination of nucleic acids and proteins of some strains of tobacco mosaic virus as carried out by FRAEN- KEL-CoN~AT and StaGER (1957) gave rise to something like "hybrids".

Even though it has not been possible to obtain new strains by influencing the virus in vitro, some authors assume (e.g. KAPITSA 1954) that changes in the properties of the virus occur not only because of the changed metabolism of the host, bu t also directly because of the affecting of the biochemical re- actions connected with the reproduction of the virus (e. g. raised tempera- tures). KAUSCHE et al. (1940) maintain, on the basis of their results with irra- diation of plants by X-rays, that the virus is influenced secondarily through the effect on the metabolism of the host and further that this takes place only if its growth is not halted.

The aim of our work has been to obtain a strain with new properties only by direct action on the metabolism of the plant which is the usual host for the virus concerned (SVOBODOV.A 1954).

Material and Methods

An effective way of influencing the metabol i sm of the host was shown to be the cul t ivat ion of dwar f plants, grown in an artificial nu t r i en t env i ronment and wi th a pe rmanen t ly limited air supply. The plants were grown aseptically on an agar medium in Er lenmeyer flasks wi th a reduc-

116 J . S V O B O D O V A

ed s u p p l y of n u t r i e n t , a n d in t he s u m m e r m o n t h s t he per iod o f i l l umina t ion was also res t r i c ted . These d w a r f p lan t s , t he m e t a b o l i s m of wh ich could be regarded as abno rma l , were in fec ted w i th t he v i rus so t h a t , a l t h o u g h p l a n t s o f t he s ame v a r i e t y were used , t he v i rus , b y be ing pa s sed t h r o u g h n o r m a l p l an t s a n d t h e n dwar f s a n d vice versa , was in t roduced in to p l an t s w i th a differ- e n t m e t a b o l i s m . The first e x p e r i m e n t a l p l an t s were Solanum lycopcrsicum var . I m u n , b u t l a te r 1Vicotiana tabacum SamsurL was f o u n d to be more su i tab le . A t t he s t a r t d w a r f p lan t s , w h i c h h a d r eached a he igh t of a b o u t 1 cm af te r five m o n t h s a n d fo rmed up to 10 sma l l leaves, were u sed (SvOBODOV~ 1954). Since in t he course of t he e x p e r i m e n t s it was f o u n d t h a t s imi la r r e su l t s could be ob t a ined w i t h less s t u n t e d p l an t s , p l a n t s were t h e n infec ted wh ich a f te r 3 - - 4 m o n t h s o f g r o w t h h a d a t t a i n e d a he igh t of a b o u t 2 - - 3 cm. (fig. 2), the i r n u t r i e n t s u p p l y be ing r educed to on ly two th i rds . Tobacco p l an t s g rown n o r m a l l y on g a r d e n soil in t he glass house were in- fec ted in a b o u t t he 6 th to 8 th week of g rowth .

As t h e ini t ia l m a t e r i a l for infec t ion we u sed t he Al - s t r a in o f toabcco mosa ic v i rus , because of all t h e s t r a i n s ava i lab le i t is s y m p t o m a t i c a l l y t he m o s t d is t inc t . Th i s s t r a i n deve loped in n a t u r e a n d was i so la ted b y BLATTN$ r in 1953 (BLATTN~ 1955). JAKUBOW5 et al. (1955) d e t e r m i n e d i ts s p e c t r u m in u l t r a -v io le t l ight , i t s e lec t rophore t ic mobi l i ty , i t s qua l i t a t ive a n d q u a n t i t a t i v e nuc lcporo te in a m i n o a c i d c o n t e n t a n d i ts morpho log ica l s t ruc tu re . I so la t ion f r o m lesions on Nicotiana glutinosa, r epea t ed m a n y t i m e s b y BLATT~:k, u s i n g ve ry d i lu ted sap, n e v e r led to t he s e p a r a t i o n o f d i f ferent forms. Nor d id th i s t ake place du r ing the m a s s inocu la t ions w h i c h h a v e been carr ied o u t each yea r for o the r pu rposes as well b y va r i ous m e m b e r s o f our s taf f s ince 1953, a t d i f ferent t i m e s o f the yea r a n d u n d e r differing t e m p e r a t u r e condi t ions on m a n y t h o u s a n d s o f tobacco p l a n t s a n d on o the r species. Accord ing to JAKUBOVIS, t he so lu t ion o f nuc leopro te in o f th i s v i rus t r ave l in t he electric field as comple t e ly h o m o g e n e o u s par t ic les .

On t he leaves of Physalis Franchetti a n d P. alkekengi, f r om which i t was isola ted, t h e Al - s t r a in g ives rise to d a r k green, whi t i sh , yellow to ye l lowish-green spots , b l is ters a n d d e f o r m a t i o n s . I t p roduces t he s ame s y m p t o m s on Nicotiana tabacum S a m s u n (fig. 1) a n d on Solanum lycopcrsi- cum. Y o u n g p l a n t s of tobacco a n d Capsicum annuum in n o r m a l e n v i r o n m e n t s are to a h igh degree kil led b y it a n d the g rowt h o f older p l an t s is inhibi ted .

The process of passing and results

Work was started in the spring of 1953. Dwarf tomato plants (in groups of ten), which had been grown under aseptic conditions on an agar medium in Erlenmeyer flasks, were inoculated with sap from tomato plants systemic- ally infected with Al-strain virus. The symptoms were very weak. The second passage was carried out on tomato plants which had been grown in the usual way on garden soil in the glass house, the third on tomatoes and on tobacco of the Samsun variety, also grown on garden soil in the glass house. The tomato plants showed atypical symptoms which were indistinct, tobacco reacted more sensitively. Two out of five tobacco plants exhibited signs of disease by a quite abnormal eolo uring of the tissues, never found before with the Al-strain. There were light "stripes" with a darker band within them, which followed veins of the Ist, IInd and partially IIIrd order (SvOBODOV), 1954), Further work was then directed to the following of these symptoms, since they were markedly distinct from all those previously observed. The other symptoms were not followed further and the changes obtained after the passage through plants grown on micro-beds (SvOBODOVA 1954) were also ignored. During the fourth passage, which was carried out again on plants grown on garden soil in the glass house, the Samsun plants showed very mild signs of disease; of five plants two were not diseased at all. In the case of three plants bulging of the intercostal areas was observed (inoculation took place in Sep-

A N E W S T R A I N OF TOBACCO MOSAIC V I R U S 117

tember 1953). This inoculation was therefore repeated on other plant species. The symptom of stripes along the veins was reproduced in three out of five plants of Nicotiana tabacum Virginian Gold. The other two remained without symptoms.

During the autumn and winter of 1953--1954 work was interrul~ted and the tobacco plants wintered in the glass house. The yellow stripes disappeared, the leaves on which they had occured died and the blades of further leaves showed yellow and green spots (SvoBoDovi 1954). Further passages were carried out in the spring of 1954. Plants grown under normal conditions in the glass house were infected with sap from the spotted leaves. The stripe symp- toms along the veins were reproduced regularly always in a certain proportion, the other infected plants remaining without symptoms. The general picture of the symptoms was as follows:

On evenly green leaves yellow stripes appear as the first symptom along the veins of the I - - I I I order, on further leaves green stripes follow and patterns of light lines and stripes, to which the original stripe gives place. With higher summer temperatures and stronger sunshine, occur later symptoms of rather yellow and green patches, similar to those with the Al-strain, Ring figuring is less frequent; the extent to which patterns occur around the spots on older leaves such as are shown in fig. 6 depends on the temperature and illumina- tion. Green stripes follow in the ontogenetical development of the plant after the yellow stripes. In milder cases of the disease, where the incubation period is longer, the yellow stripes may, however, be altogether lacking; in this case 1--2 leaves above the inoculated leaf remain without symptoms and on further leaves there appear green stripes and then spots and patterns.

The development of new symptoms was reproducible. Since it was found that the tomato is not very suitable as material, at tention was again directed to the effect of other host plants. In October 1953 tobacco and tomato plants were simultaneously infected. The plants were grown aseptically on agar. The original material used in this case, as distinct from the first experiment, was sap from Nicotiana tabacum Samsun (fig. 1) systemically diseased with the Al-strain. In the first series it was always passed through Nicotiana tabacum Samsun plants on an agar medium. The plants showed indistinct symptoms until in further infections (from the 3rd to 4th) they showed none at all even when transplanted into garden soil in Petri dishes 4 cm. in diameter, where nutrients were restricted but they were in a free environment. Only after repeated infection of plants in Erlenmeyer flasks by sap from plants systemically diseased with Al-strain and grown under normal conditions in the glass house, the symptom of yellow stripes along the veins again occur- ed in further passages. This occurred in the following cases:

a) Following inoculation to plants in garden soil in the glass house immedi- ately at the next passage in June 1954, but to a rather weaker degree. Clear symptoms were found only in one out of five Samsun plants, where they appeared later and as green stripes.

b) Following inoculation to plants grown on agar medium, where symptoms appeared only after the second further passage in November of the same year.

118 J. SVOBODOVA

Two of the Nicotiana tabacum Samsun plants on an agar medium, which have been mentioned above as showing no symptoms after the third passage were transplanted into garden soil in flower pots and left in the laboratory next to plants on an agar medium. After transplantation spots appeared on these plants, in contrast to those transplanted into Petri dishes; in the further passage (the fourth), however, yellow stripes appeared, both on plants in garden soil in the glass house, where they developed in May 1954, and on plants on agar, where they developed in April of the same year.

In further passages the stripes along the veins were reproduced without change, both in winter and summer (in artificial culture on agar). Sap from plants, which exhibited stripe symptoms in August 1953, in April 1954, in June and November 1954 was used in separate passages up to twenty times and the symptoms were maintained without change. Nor was there any difference between plants of different experimental series. The results were also the same whether the original material was taken from tomatoes or tobacco var. Samsun.

The general picture of the symptoms remained unchanged whether the inoculation material was taken from individual leaves or different parts of them with yellow or green stripes, with spots and light green patterns. Also when

~the passages were repeated several times from Samsun plants grown in normal glass house environment to Samsun plants on agar, sap being selected for the purpose from tissues with different symptoms, the same symptom picture developed; in the first passage they were rather weak and often were seen for the first time at the green stripe stage; however, in further passages through tobacco plants on agar the yellow stripes regularly appeared as the first symp- tom. Following passage of the sap from normal plants back to dwarf plants in artificial nutrient there were also no further changes, only in the first passage a certain weakening of the symptoms was observed. The symptoms described became permanent on tobacco.

In order to confirm the fixation of these symptoms, sap from Nicotiana tabacum Samsun plants evincing these symptoms was passed to the following plants: !Vicotiana sylvestris, Nicotiana glutinosa, N. a//inis, iV. tabacum White Burley, N. t. Virginia Golden, Solanum lycopersicum, S. tuberosum, Physalis alkekengi, P. Franchetti, Capsicum anuum.

Although individual host plants reacted differently, after passing back to Nicotiana tabacum Samsun the original symptom, a stripe along the veins, appeared again without change. This, together with the fact that these symp- toms have been maintained without change for six years through annual mass inoculation, permits the conclusion that the change is permanent and has de- veloped independently of the species of host and is not changed by passage through the host plants named.

During the winter of 1953--54 the new virus was preserved in live plants, in 1954/55 and subsequent years it was kept in dry leaves. After carrying out the appropriate tests, which will be published, the new virus was identified as a new strain of the tobacco mosaic virus. I t was called S-strain of tobacco mosaic virus from the stripe symptoms which it forms on tobacco leaves.

A m E W S T R A I N OF T OB AC C O MOSAIC V I R U S 119

Diseussion

The symptoms of yellow and green spots on leaves of the medium level cannot be regarded as a sign of a reversal to the original Al-strain, because:

1. I~einoculation with sap from the tissues of these parts always produced the typical symptom picture for the S-strain and isolation from individual spots and from lesions did not lead to the selecting out of the Al-strain.

2. The only common symptoms with the Al-strain are these patches and they sometimes appear only temporarily. With the S-strain, however, deforma- tion of the blade and albinism is completely lacking (as distinct from the A1- strain). With the Al-strain the youngest leaves are commonly very strongly affected, while the opposite is the case for the S-strain, the youngest leaves usually remain unaffected.

The symptoms are also reproduced without change in passages through plants from a normal glass house environment followed by passages through plants on agar if it is carried out by selection of sap from tissues with different symptoms (with yellow or green stripes, with yellow or green spots and rings); thus not even this method produced a new form. The stylisation used by Svo- bodovs in 1954, when the occurrence of these spots gave rise to uncertainty as to whether a permanent change is involved, is now therefore made precise. The permanency of these symptoms is further confirmed by the fact that in four reproductions of the origin of the S-strain no symptomatic differences were observed, although the different reproductions were carried out at differ- ent times of the year. The results were also the same whether sap from toma- toes or from tobacco was used as the original material.

As shown by the passage of the virus through dwarf plants on micro-beds in a free environment (SvOBODOV~ 1954), the changed metabolism of the dwarfs did not suffice to produce the change from Al-strain to S-strain; it was necessary to influence the metabolism by an abnormal environment in Erich- meyer flasks after inoculation. The reduced metabolism of the dwarfs inhibited the development of the virus, but did not change it qualitatively.

I t was also found that neither the passage of the virus to dwarf plants on micro-beds nor on agar sufficed in itself to produce the change. Here also there was only a weakening amounting almost to disappearance of the symptoms. A twofold change in the environment of the virus was necessary to achieve the symptoms described: first of all passage from normal plants to dwarfs and then from dwarfs back to normal, where the virus once again had normal conditions for reproduction. In the subsequent (third) passage to normal plants the change became apparent. The ease was similar when a plant infected with Al-strain and grown on agar was transplanted and grown further in normal conditions. In the subsequent passage (again the third) through plants grown on agar, the same change occurred. The symptoms of S-strain appeared in the third passage without regard to whether the plants used were grown in garden soil in the normal way, or were dwarfed plants; but before this the virus had to undergo at least twice the change of host environment described.

In the work of PFA~C~UC~ et al. (1940) the strain T~44 is described, which

120 J. SVOBODOVA

according to the symptoms is in some respects similar to the S-strain. I t was developed from an ordinary green strain of tobacco mosaic through X-ray irradiation of the host plant. The lighter colouring of the tissues along the veins is, however, described in the case of TM44 as a secondary symptom; with the S-strain it appears as the first symptom on the inoculated leaves. The remain- ing symptoms are quite different. The incubation period for the TM44 type disease is, similarly to tha t for the S-strain, longer than for ordinary tobacco mosaic virus. The pathogenity of TM44 was, however, increased as compared with the initial ordinary strain, while that of S-strain was lower as compared with both the Al-strain and the ordinary green strain. An increased variability in the expression of the symptoms in relation to conditions of illumination was also observed in both cases. I t would seem that the influence of the X-rays on the metabolism of the host produced a similar reaction to that of a brief period of cultivation of the virus in dwarfed plants in which the reproduction of the virus over a certain period was limited.

According to the opinion of KACSC~E et al. (1940), mutation is not to be regarded as a direct change of virus molecule induced by an influencing factor (a changed substratum) but it appears in the course of the reproduction of the virus molecule in a changed substratum, provided that the synthesis of proteins in an irradiated organism is not inhibited by the stoppage in the total growth. Similarly, no change occurred in our work either in the dwarfed plants in which growth was not completely stopped, (as by X-ray irradiation), but greatly inhibited. The change in symptoms did not occur until after passage into normal plants, that is, as with KAUSCHE, when the reproduction of the virus was not being inhibited by the arrested growth of the host plant. These plants, in contrast to irradiated plants, were absolutely unaffected.

In most of the work on the origin of new strains a dominant question is whether the new strain has arisen by mutation or by selection (e. g. KASSANm 1957). Recently an increasing number of authors have been producing evidence of the bringing about of mutation. For example, MUNDI~Y (1957), after ob- serving all possible precautions in his work, comes to the conclusion that in the change from green to yellow strains and the reverse, achieved under the influence of changed temperatures of the leaves, it is not a matter of selection but of true mutation. The TM44, above mentioned, is also a result of a mutation. The aim of this work was to establish whether a change in the metabolism of a host plant of the same species and variety through a change in its environ- ment is sufficient to call forth an alteration in the properties of the virus. The question whether this change in properties is due to mutat ion or selection has been left aside, although for a number of reasons we consider the possi- bility of selection to be less probable in our case. The strong dependence of the virus on the metabolism of the host, the evidence for which becomes clearer and clearer, is in our opinion a reason for the tendency to variability of the properties of the virus.

J. SVOBODOV.~

A NEW STRAIN OF TOBACCO MOSAIC VIRUS

Fig. 1. Fig. 2.

Fig. 1. N i c o t i a n a tabacum Samsun , s y s t e m i c a l l y di~.eased w i t h Al-st l .a in. The sap from th is p l a n t was the or ig inal m a t e r i a l for pass ing , which led ta the d e v e l o p m e n t of the new s t r a in (S-strain).

Fig. 2. Dwar fed p'~rLt of N i c o t i a n a tabacum Samsun, 3*/2 monf, hs old ( ( l l 8 days) , before infect ion. The p la t ~ is fo rming aer ia l roots.

F ig . 3. Fig. 4.

Fig. 3. N i c o t i a n a t a b a c u m Samsut~ p l a n t d iseased w i t h the S s t r a in of TMV. Yel low s t r ipes a long the veins of the leaf n e x t above the inocu la ted leaf.

Ficr ~ ~J4en#4n~rt trlhrteaJ~ ~flmqlln nlnnt.~a cli~r wlt,h ~hr R.~acrnin ~c TMV V~ll~x~ o§

J. SVOBODOV•

A NEW STRAIN OF TOBACCO MOSAIC VIRUS

Fig. 5. F~g. 6.

Fig. 5. Nicot iana tabacum SamsmL I n the fm.bher course of the S-strain disease spots, which under favourable conditions of i l lumination and tempera ture are bordered by bands, are formed beside the green stripes along the veins.

Fig. 6. Stripe pa t t e rns on older leaves of fully grown Nicot iana tabacum Samsun plants diseased with the S-strain of TMV.

Fig. 7. Fig. 8. Fig. 7. Yellow str ipes along the veins of a Nicot iana tabacum Samsun plant on agar medium in

an Er lenmeyer flask (S-strain TMV). Fig. 8. Green stripes along the veins of a Nicot iana tabacum Samsun plant on agar medium (S-strain

TMV).

A N E W STRAIN OF TOBACCO MOSAIC VIRUS 121

References

BAWDEN, F. C.: Reversible, host induced, changes in a strain of tobacco mosaic virus. Nature 177 : 302--304, 1956.

BLATTN~, C.: Alke-kmen viru oby6ejn~ tabAkov6 mosaiky (VTM 1). (The Al-strain of tobacco mosaic virus.) - - Sb. prAe o t abaku SAV, 231--264, 1955.

FRAENKEL-CONRAD, H., SINGER, B., Virus reconst i tut ion II. Combination of protein and nucleic acid from different strains. Biochem. biophys. Acta 24 : 540--548, 1957.

JAKUBOVI0, A., ~LECItTA, L., KEIL, B., ~ORM, F.: SrovnAvaci studie dvou kmenfl tabhkov6 mosaiky. (Comparative s tudy of two strains of tobacco mosaic virus.) - - Chem listy 49 : 1561--1564, 1955.

KAPITSA, O. C.: Adekva tnaya izmenchivost v i rusa tabactmoy mozaiky pri vozdeystvii po- vyshennych tempera tur . (Adequate variabil i ty of tobacco mosaic virus under the influence of increased temperatures.) - - Tr. inst. genetiki AN SSSI~ 22 : 181--207, 1954.

KAUSCHE, G. A., RUSKA, H., STUBBE, H.: Zur Frage der En t s t ehung r6ntgenstrahleninduzierter Mutat ion beim Tabakmosaikvirusprotein. - - Naturwissenschaf ten 28 : 824, 1940.

KASSA~IS, B. : Some effect of varying tempera ture on the quality and quant i ty of tobacco mosaic virus in infected plants. Virology 4 : 187--199, 1957.

KV~KEL, L. O.: Effect of hea t on ability of Cicadula sexnota ta (Fall.) to t ransmi t aster yellow. - - Amer. J. Bet . 24 : 316--327, 1937.

LARSOI~, R. H., STAHMANN, M. A., WALKEI~, J. C.." The induction of m u t a n t s in potato virus X by nitrogen mustard . Proc. 2rid Conf. on potato virus diseases. Wageningen, It. Veenman et Zonen 1955.

MELCHERS, G., MUNDRu W.: , ,Mutat ion" und , ,Ri ickmutat ion" beim Tabakmosaikvirus in Abh/i~gigkeit yon dcr Ku l tu r t empera tu r der WirtspflarLzen. Proc. 9th Internat . Congr. Ge- netics 1953. Caryologia (Pisa) Suppl. 1106, 1954.

MUNDRY, K. W.: ]Die Abh/~ngigkeit des Auftretens neuer Virusst~mme yon der Kul tur tempe- ra tur der WirtspflarLzcn. Z. Vererbungslehre 88 : 407--426, 1957.

PFANCHUCH, E., KATJSCHE, G. A., STUBBE, H.: Uber die Ents tehung , die biologische trod physi- kalisch-chemische Charakterisierung yon R6ntgen trod y-Strahlen induzierten , ,Mutat ionen" des Tabakmosaikvirusproteins. Biochem. Ztschr., 304 : 238--258, 1940.

SUKHOV, K. S.: Izmenchivos t virusov pri smeshannych infekciyach. (Variability of viruses in- duced in mixed infections.) - - Izv. AN SSSR ser. biol. 7 : 80--88, 1955.

SvK~OV, K. S., KAPITSA, O. C. : Naprav lennaya izmenchivost X-virusa kartofelya pri smeshan- noy infekcii s v i rusom tabachnoy mozaiky. (The variabili ty of the potato X virus induced in mixed infection with tobacco mosaic virus.) - - Izv. AN SSSR : 53--64, 1956.

SVOBODOV~, J . : P~stovhni rostlin na mikroz~honu a aseptieky na agaru jako p~isp~vek k mete- dice zm~ny virfl. (Cultivation of plants on micro-beds and aseptically on agar as a contri- but ion to methods of changing properties of viruses.) ~s. Biologie (Praha) 3 : 370--375, 1954.

SVOBODOV-~, J.: O vlas tnostech nov/$ vznikl~ho kmene VTM (S-kmene). (On the properties of a newly developed s t ra in of VTM (S-strain). Preslia 30 : 359, 1958.

Address: In~. Ja rmi la SvobodovA-~ajnerovA, Ins t i tu te of Biology of the Czechoslovak Academy of Sciences, Depar tment of P lan t Pathology, Na Karlovce 1, P raha 6, Dejvice.

122 A N E W S T R A I N OF TOBACCO MOSAIC V I R U S

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