Red - Far Red Light Effects On the Adenylil Cyclase and Guanylil Cyclase Activity of Sorghum bicolor Seedlings. Kerim G.Gasumov, Chizuko Shichijo*, Tohru Hashimoto* Institute of Botany, Azerbaijan Academy of Sciences, Patamdar Shosse 40, Baku 370073, Azerbaijan Republic, *Department of Biology, Faculty of Science, Kobe University, Rokkodai, Nada-ku, Kobe 657, Japan, Abstract - Using monochromatic and dichromatic radiation we have shown that reaction of adenylil cyclase (AC) and guanylil cyclase (GC) of Sorghum bicolor seedlings are differently at the different period of year. The activity of AC mainly very high in summer period and strongly reacted on the action of R light. At the early autumn it disappeared and it was appeared again in middle of winter. But the higher GC activity was registered at autumn period and it decreased at the winter when increased AC activity. Probably both of these cNMPs participate in the phytochrome photosignaling and during of year one may substitute for another, although there is possibility participation both of these cNMP in photosignal transduction processes in the same time. INTRODUCTION MATERIALS AND METHODS. In experiments Sorghum bicolor as a plant material was used. Seeds of Sorghum bicolor Moench, cv. Acme Broomcorn 1995 crop from Kobe University Farm at Kasai, were soaked for 24 h in water bath of 24oC, in which temperature-adjusted tap water being supplemented circulated. From sowing to irradiation seedlings were grown in the dark at 20oC for 5 days. Irradiation of seedlings and light source Nucleotide cyclase preparation. Adenilil and Guanilil cyclases assay. RESULTS We have isolated membrane fraction of protein riched by cyclase activity from 5 days etiolated Sorghum bicolor seedlings and this fraction was subjected to adenylil cyclase (AC) and guanylil cyclase (GC) activities assay. We have found the higher cyclases activity in membrane fraction of seedlings and optimal enzyme activity was occurred in moderately alkaline medium - pH 7.8. We determined that, the higher AC activity appeared in summer and early autumn period. But in the middle of autumn the activity of AC disappeared, and it was again appeared only in the middle of winter. On the contrary of AC the activity of GC in summer and all period of autumn was very higher. And beginning with middle of winter it was getting down the GC activity when starts of increasing of the AC activity. Red and far red light effects on AC and GC. Before isolation of enzyme fractions we irradiated seedlings separately by red (R) and far red (FR) lights and by their combination - irradiation of seedlings by far red light just after red illumination (RFR). Immediately after illumination of seedlings they subjected for isolation membrane fraction of cyclases activity. Irradiation of seedlings by R and FR lights led to significantly alteration of AC and GC activities. We determined that the alteration of AC and GC activity, caused by monochromatic lights was differently in the summer and winter season. Beginning with of summer AC of the etiolated Sorghum seedlings grown in 20o was activated by FR strongly (July -early September) and this activation was observed by irradiation of seedlings with RFR too. Irradiation of seedlings by R in this period did not show any effect on AC activity (Fig.1A). But in the middle of winter when appeared AC activity again we determined activation of AC by all versions of irradiation - R, FR and RFR (Fig.1B). As compared with AC, the GC isolated from etiolated seedlings significantly activated by R and FR lights which behavior of GC may be predictable, based on current knowledge of the actions of phytochrome A and phytochrome B (Smith et al., 1997). The activation of GC by R and FR lights we observed repeatedly in all autumn experiments (Fig.2A). Moreover in this period D and FR irradiated activity of GC in compare of summer period was much higher, and higher activity of GC has been continued until of winter. But beginning with of January it became decreasing, where in this period we determined increasing of AC activity of D and irradiated seedlings. Although the total activity of GC in middle of winter was decreased but its reaction to monochromatic lights effect was determined (Fig.2B). DISCUSSION. Alteration of activity of the AC and GC enzymes caused by
monochromatic lights testifies the red and far red light
fotoreceptors' - phytochromes participation in this regulation
processes. Activation of AC in etiolated seedlings by FR light
appeared more strongly in summer and early autumn. It is
obviously that the same feel of AC to light treatment duration of
Summer and Autumn is a result interaction of this enzyme with
phytochrome A. With coming late of winter and early spring the
sensitiveness AC was increased to R and FR light too. It seems to
be AC this period responsible to the action of phytocromes A and
B i.e. activated phytochromes absorbing R and FR lights cause
some photoinversion of AC, although there is a possibility
participation of multiform of AC which differed by responsiblity
to light effects. And also there is probability of the GC
participation in the transduction of photosignal from
phytochromes. Higher GC activity in the autumn, when there is
absent AC activity, and reaction of GC to red and far red light
effects testifies that cGMP system also as a cAMP may become
secondary messanger of photosignal transduction. Probably both of
these cNMPs participate in the phytochrome photosignaling and
during of year one may substitute for another, although it is
possible both of these cNMP in the same time participate in
photosignal transduction processes. At the end of winter and
early spring observed activation of GC by red light, although
total activity of enzyme was lower than autumn season testify
that, GC like as a AC can be interacted with different forms of
phytochromes and two cNMP systems differ in the relation with
phytochromes in different period of year. Acknowledgements -The authors gratefully acknowledge
Japan Society for the Promotion of Science for the funding of
this work and the Experimental Farm, Kobe University, Kasai for
seeds. LITERATURE CITED Bowler, C., Neuhaus, G., Yamagata, H., and Chua, N.-H. (1994a), Cyclic GMP and calcium mediate phytochrome phototransduction. Cell, 77, 73-81. Fedenko, E.P., Ivanova, M.A., Doman, N.G. (1983) Adenylatecyclase and Phyto- chrome. Doklady Academiya Nauk of SSSR, V.269, No 5, p.1267. Fedenko E.P., Kasumov K.K., Doman N.G., (1988) Cyclic AMP phosphodiesterase and phytochrome. Izvestiya Akad. Nauk of SSSR, seriya biologicheskaya, No 5: 740-745. Mohr, H. (1972) Lectures on Photomorphogenesis. Berlin , Springer, p.113. Ohmori M., (1989) cAMP in Anabaena cylindrica: Rapid changes in cellular levels in response to changes in extracellular environments. Plant Cell Physiol., 30: 911-914. Ohmori M., Katayama M., Kasahara M. and Sasaki S., Adenylate cyclase of cyanobacteria and photosignal transduction. NIBB International Symposium "New Prospects of Photobiology...", 12-14 Nov. 1996, Okazaky, Japan, <V-4>. Rast, D., Skrivanova, R., Bachofen, R. (1973) Replacement of light by dibutyryl- cAMP and cAMP in betacyanin synthesis. Phytochemistry , V.12, p. 2669 Shichijo Ch., Hamada T., Hiraoka M., Jonson C.B., Hashimoto T., (1993), Enhancement of red-light-induced anthocyanin synthesis in sorghum first internodes by moderate low temperature given in the pre-irradiation culture period. Planta, 191, 238-245. Smith H., Xu Y. and Quail P.H., (1997) Antagonistic but complementary actions of phytochromes A and B allow optimum seedling de-etiolation. Plant Physiol. 114: 637-641. |