A COMPARISON OF STOMATAL BEHAVIOR BEFORE AND AFTER FLOWERING IN THE ARGENTEUM MUTANT OF PISUM SATIVUM

PNL Volume 15 1983

RESEARCH REPORTS 13

A COMPARISON OF STOMATAL BEHAVIOR BEFORE AND AFTER FLOWERING IN THE

ARGENTEUM MUTANT OF PISUM SATIVUM

Donkin, M. E., and E. S. Martin Plymouth Polytechnic

Plymouth, U. K.

Hull, T. Rumleigh Experiment Station, Bere Alston, U. K.

The recently described Argenteum (.Arg) mutant of Pisum (4,5) has

proved to be extremely useful for the investigation of stomatal physiol-

ogy in the pea plant. This mutant, which is characterized by a silvery

appearance of the leaves, has been shown to have extensive intercellular

air spaces between the epidermis and the mesophyll tissue (2) which

makes the epidermis easily removable for stomatal studies.

Some studies of the stomatal behavior of this mutant have been

carried out (1,3) but so far as we know no work has been done on the

stomatal response to flowering in Arg or indeed in any other variety of

pea. This may be an important omission since during the process of

flowering and pod production hormonal changes take place which may in-

fluence the behavior of the stomata and subsequently the overall

physiology of the plant.

We have therefore carried out a designed experiment (details in

legend to Fig. 1) in which the stomatal responses to light and CO₂ of

detached epidermis were investigated In non-flowering and flowering Arg.

plants. The results shown in Fig. 1 indicate that overall the stomatal

apertures are reduced in the flowering plants. It is also apparent that

the stomatal response to light is decreased in the flowering plants par-

ticularly in the absence of CO₂ but the response to CO₂ is similar in

both flowering and non-flowering Arg plants. These conclusions were

confirmed by subjecting the data to analysis of variance, which showed

that there were large significant effects (P=0.001, df=7) of light, C0₂

and flowering, with a significant interaction between light and flower-

ing (P=0.05, df=1,7), but no interaction between C0₂ and flowering.

Interpretation of these results is difficult since under these con-

ditions we cannot separate an. effect of age from an effect of flowering,

the flowering plants being several weeks older. However, the leaves

used for the flowering plants were not showing any signs of senescence.

The most interesting feature would seem to be that of the effect of

flowering on the light response of stomata without an effect on the CO₂

response. The explanation for these observations may lie in the sensi-

tive balance of key hormones at this stage of development, since the

ratio of the hormones IAA/ABA are known to affect stomatal opening.

1. Donkin, M. E., A. J. Travis, and E. S. Martin. 1982.

Z. Pflanzenphysiology 107:201-209.

2. Hoch, H. C, C. Pratt, and G. A. Marx. 1980. Amer. J. Bot. 67:905-

91 1.

3. Jewer, P. C. , L. D. Incoll, and J. Shaw. 1982. Planta 155:146-153-

4. Marx, G. A. 1978. PNL 10:34-37-

5. Marx, G. A. 1982. J. Heredity 73:413-420.

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RESEARCH REPORTS

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Fig. 1. Diagram to show the effects of light, C0₂ and flowering on

stomatal aperture in detached epidermis of Argenteum.

Lower epidermis was detached from leaves of non-flowering (140 cm

tall) plants or flowering plants (180 cm tall) of the Argenteum

mutant of Plsum sativum. The epidermal strips were floated on

25 mM KC1 in 10 mM MES buffer pH 6.15 in small Petri dishes which

were illuminated from the bottom through a water bath at 25°C. The

treatments applied in a randomized block design with two replicates

were +/- light, +/-C0₂ and flowering or not-flowering. The diagram

shows the mean apertures for each treatment and the bar represents

the Least Significant Difference (P=0.05, df=7).



14 PNL Volume 15 1983	RESEARCH REPORTS

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Fig. 1. Diagram to show the effects of light, C0₂ and flowering on stomatal aperture in detached epidermis of Argenteum. Lower epidermis was detached from leaves of non-flowering (140 cm tall) plants or flowering plants (180 cm tall) of the Argenteum mutant of Plsum sativum. The epidermal strips were floated on 25 mM KC1 in 10 mM MES buffer pH 6.15 in small Petri dishes which were illuminated from the bottom through a water bath at 25°C. The treatments applied in a randomized block design with two replicates were +/- light, +/-C0₂ and flowering or not-flowering. The diagram shows the mean apertures for each treatment and the bar represents the Least Significant Difference (P=0.05, df=7).