Protoplasts from plants are suitable experimental objects for investigations in which substances are taken up by cells, since chemicals can reach the cell surface directly. Therefore, it is convenient to use them for experiments concerned with effects of phytohormones on metabolism. So far, some work on the application of auxins 1-3 has been described, and recently we have made some investigations on the influence of zeatin on photosynthesis and respiration of isolated mesophyll protoplasts from Petunia.Inkubation mit Abscisinsäure verursacht bei Mesophyll-Protoplasten von Petunia hybrida einen Anstieg der Photosyntheserate

Hoffmann, Franz

Kull, Ulrich

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746 Specialia EXP>:lI.t'ENTI.-.30/7 
Effects of Abscisic Acid on Photosynthesis of Protoplasts from Petunia hybrida 
Protopiasts from plants are suitable experimental 
objects for investigations in which substances afC taken 
up by cells, since chemicals can reach the cell surface 
directly. Therefore, it is convenient to use them for 
e:<pcriments concerned with effects of phytohormone-<; on 
metabolism. So far, some work on the application of 
auxins!"" has bt!en described, and recently we have made 
some investigations on the influence of zeatin on photo-
synthesis and respiration of isolated mesophyU protoplasts 
from Petunia (KtJLL and HOFFMANN, in preparation). 
Application of abscisic acid (ABA) kads to a decrease of 
photosynthetic rate in treated leaves, very likely due to 
stomatal closure caused by the phytohormone~-I. Some 
observations' suggest that mesophyll photosynthesis.is 
not affected directly. RccenUy. it was found that in 
illuminated and unilluminated dark grown Avena seed-
lings and in otio-chloroplasts of the same species, ABA 
reduced the levels of r ibulosediphosphate carboxylase 
activityi-. We studied the effect of ABA on the photo-
synthesis of mesophyl1 protopiasts from Petunia. The 
influence of ABA on the respiration of these isolated 
protoplasts was briefly investigated in connection with 
our work on zeatin. 
, D. W. GREGORY and E. C. CoCIUNf., J. expo Bot. 17,68 (J966). 
I J. B. POW£I< and E. C. COC"'N(:, J. expo Bot. 21, 64 (2970). 
• M. H. B.wu, Plant Phyo;iol. 51, 898 (1973). 
• C. J. M,rrl1>LBKUSKR and R. F. M. V".!f STKIII!:N'NCK, Nature, l.<:Ind. 
221,281 (1%9); Plauta 97, 83 (J971). 
t W. R. CtlJIH'~S, H. I{~ND£ alld K. RASOII<£, Plantagg, 347 (1971) 
• J. POSKUT .. , R. A~T05~EWS1<J and M. FALTYl<OWIC;~, Photo-
~ynthetica 6, 370 (1972) . 
, R. J. JOII'£S and T. A. 1'11 ,,11'51"1\1,.1), Phy>;iok>gia plaut. 26, 32t 
12972). 
S F. A. ~j". WIiUBIiRN, A. R. WIIL.I,.BVBN, J. L. STODDART and 
K. J. TUH .. R>iU::, »lanta 111, 337 (1973). 
15,7. 19i4 Specialia 747 
Effect of abscisic acid on the photOl;ynthetie rate of isolated mesophyll protoplasts from Petllni4 kybrirta 
Time 
ABA acting (h) 
, 
2 
3 
Controls _ 100%. 
Concentration of ABA (racemate) 
1 ppm 5 ppm 
3.8fLU/1 
100 ± 4.5 
100 ± 4.5 
tOO ± 4.3 
19!J.M/l 
100 ± 4.5 
100 ± 4.5 
103 ± 4.5 
The mesophyl1 protoplasts from Pelu'lia lIybrida were 
produced by methods already described •. 10. 1n scintillator 
vials J 0' protopiasts in 1 ml medium (0.4 M mannitol! 
0.23 M NaHCOl , ratio 95: 5; with 0.22 M HCl brought to 
pH 7.2) were incubated with ABA (racemate) of different 
concentrations (Table) for different times (1 - 3 h ). Then 
2 v.Ci of NaIF'CO, in 100 v.1 0.4 M mannitol were added 
and the probes were illuminated for exactly 10 min in an 
illuminated therUlostate (8 x40 'IN Osram-L-Warmton 
lamps, ca_ 9000 lux, temperalure 24 QC). After this, hol 
ethanol was added and the vials boiJed for 2 min. After 
transferring into 50 ml graduated vessels and filling with 
60% ethanol, the Jiqnid was boiled again for 30 m in, then 
the vessels filled up with ethanol. The activity of an 
equivalent of this final solution was measured in the 
scintillation counter in dioxane cocktail (gain 83%). 
Since ABA must be brought in solution with a few 
droplets of ammonia, the concentration of the latter 
rises with increasing concentration of the hormone. 
Therefore the respective concentrations of N H3 were 
established in the controls. Always after addition of ABA 
or - in the controls - of NHs alone, the pH was adjusted 
again to 7.2. Due to the riSing quantities of NHs, the 
absolute rates of photosynthesis, measured as amount of 
14CO~ fixed, are not comparable; in the controls they 
decline. (In t set of control experiments without any 
.:-.rH3 added, the "fate is 2.98 !J.M COt/mg chlorophyll ill 
10 min; this is in good agreement with our earlier find-
ings). Therefore the results arc given as percentage of the 
photosynthetic rate of the respective controls. Each 
experiment was done 3 times together with 3 controls. 
The results are shown in the Table. A rise of the 
photosynthetic rate caused by ABA can be seen. A 
marked effect needs relatively llighconcentrntions of ABA 
with respect to naked protoplasts. With 1.9 X 10- ' Mil 
ABA after 3 h the increase of the photosynthesis reaches 
nearly 100%; with 7.6xlO-' Mil the effect is consider-
ably lower, probably due to all inhibitory effect of very 
high concentrations of the phytohormone_ 
To a certain e.xtcnt the results arc surprising, con-
sidering that ABA is a scnescence-prOllloting hormone ll. It. 
The concentrations of ABA whjch cause a rise of the 
photosynihetic rate of mesophyU protoplasts arc a 
grea t deal higber than those needed for closure of stomata 
and the subsequent inbibition of photosynthesis of 
10 ppm sO ppm 200 ppm 
38;.tM/1 190;.tM/1 n O!J.M/1 
100 ± 4.S 
104 ± 4.5 131 ± 3.0 
123 ± 3.0 198 ± 3.0 116±3.0 
leaves ' . Therefore an unspecific ellect of ABA cannot be 
fully e.xcluded. The results show the effects of a phyto-
hormone on isolated cells in this case to be different from 
those on the whole leaf as a target. Under normal physio-
logical conditions ABA is effective in whole tissues, 50 in 
evolution the function of the phytohormone was determin-
ed by selection in respect to the whole system and not to 
single cells. 'Ve think the results arc explained best, in 
agreement wi th the findings of some other authors, as an 
effect of ABA on roembtanc permeability" l~, or the 
activity of ion uplake'.u- u . The reported' reduction of 
the activity of ribulosediphosphate carboxylase activity 
is dtle to an inhibition of plastid development and is not 
contrary to our findings with 'adult' cells I? 
Zusa'ltmenfassung. [nkubation mit Abscisinsaure ver-
ursacbt bei Mcsophyli-Protoplasten von Petunia kybrida 
eincn Anstieg der Photosyntheserate. 
F . HOHMANNI8 and U. KULL 
Lehrstuhljiir Botanische EntwickluJigsPhysiologie, 
Universittit llohenheim, EmiHVoltt-Slrusse, 
D- 7000 Stuttgart 70, and Biologisthes fnstitut del' Uni-
versitiit Stuttgart. Ulmer Strasse 227, 
D- 7000 Stuttgart 60 (rederal Republic of Germany) . 
11 February 1974. 
• 1. Porl/YI/vs and ]. DURASD, Nature New BioI. 237, Z86 (1972). 
10 F. HOFF)lA"II, Z. Pflam:enphysjol. 69, 249 (1973). 
11 F. T. ADDlce,.,. and J. L. Lyos, A. Rev. Plant Pbysio!. 20, 139 
(1969). 
.. B. V. flhLBOllROW, Sci. Prog., Lond . 57, 533 (1969). 
,. Z. G'.ISK" and L. RIliNHO!.D, Plant Physio!. 48, 103 (197t). _ 
Z. GUSKA, Plallt Physiol. 51, 217 (1973). 
If T. A. M""SI'I£LD aud R. J. Jos£s, Plauta 101, 147 (1971). 
11 R. F. i'of. VAS STF.V>:I<ISCK, Z. PflanzcnphysioJ. 67, 282 (1972). 
1& G. N. BROWN and C. Y. Su~·, Physio1ogia plant. 28. 412 (l97J). 
" This work was supported by the German BllndcsrniDisier;lllfl fiir 
Wisscnschaft und Forschung and by the Deutsche Forscbungsge-
meinschaft. We thank Prof. Dr. D. HESS for a hclpful discussion, 
Mrs. A. KR"tlS for te<:hnlcal a5Sisl:mce and Mr. P. C!.£ARY for 
conttlion of the Euglish text. 
IS New address: ;\lax-Planck-Institut fiir Pflanlcngcnetik, Rosenhof, 
1)..(5802 J.adenburg. 


Effects of abscisic acid on photosynthesis of protoplasts from Petunia hybrida

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Effects of abscisic acid on photosynthesis of protoplasts from Petunia hybrida

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