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Morphactin-induced negative geotropism of adventitious roots of Zea mays L.
Biochem. Physiol. Pflanzen (BPP), Bd. 164, S. 191-194 (1973) University Gardens, University of Delhi, India
Short Communication
Morphactin-induced negative geotropism of adventitious roots of Zea mays L. By M. IL Y AS, B. BARMA and K. K. MAGGON (Received September 19, 1972)
Summary Morphactin (Chlorflurenol) induced adventitious roots of maize to grow upwards out of the soil, the number of such roots increased with the concentration. The effect was temporary and roots could grow downwards. The amount of Indole-3-acetic acid was not altered but that of 5-hydroxyindolyl acetic acid and Indole-3-acetonitrile decreased while that of Tryptophan increased slightly.
Introduction
Morphactins are reported to interfere with geo- and photo-tropic responses of the radicle, hypocotyl and coleoptile of certain plants (KHAN 1967; HARADA 1967; KRELLE and LIEBERT 1968; B6PP 1969). Such phenomenon could be explained on the presumption that morphactin interferes with polar transport of auxin, auxin synthesis or enzymatically controlled IAA metabolism (ScHNEIDER 1970). The present work was conducted to study the effect of morphactin (Chlorflurenol IT 3456), on th.e roots of maize in field conditions and also to study its effect on the indole compounds contained in the roots from the treated and untreated plants. Materials and methods Four week old (8-10 leaves stage) Zea mays L. var. Deccan plants raised 45 em apart in field were sprayed with an aqueous 'solution' of the morphactin. The concentrations used were 25, 50, 1:00, 250, 500 and 1000 ppm ( +0.02% Tween 80 - as surfactant). The controls - one set received only the surfactant while another set remained without spray. Fifteen plants were used for each treatment. The plants were sprayed once again after ten days. The resulting negatively geotropic roots from treated plants (500 and 1000 ppm) and pqsitively geotropic roots from the controls were collected a week after the second spray and washed with distilled water. 5 g roots from each sample were crushed and extracted with Ether and the indole compounds separated by two dimensional thin layer chromatography according to STAHL and KALDEWEY (1961). The indole compounds were ob~erved by their fluorescence in ultra violet light after spraying with formaldehyde-hydrochloric acid reagent. The indole compounds were identified by co-chromatography and ultra violet _spectra with standard indoles obtained from Sigma
192
M. ILYAS, B. BARMA and K. K. MAGGON
Fig. 1. Basal portion of a plant showing negatively geotropic roots at node six. gatively geotropic roots. PGR = Positively geotropic roots.
NGR
=
Ne-
Chern. Co., St. Louis, USA. A visual comparison of the fluorescence intensity of the spots with standards of known concentrations gave an idea of the amount of the indole compounds present in each sample as done by GoPAL et al. (1971).
Results and Discussion
Four days after the second spray the ~ntrols and plants treated with 25 ppm morphactin showed normal growth of roots, but plants treated with 50 ppm and above showed roots growing up out of the soil. The number of negatively geotropic roots increased with concentration (table 1). The crimson, thick roots continued to grow upward as long as 11 em for a week after which they started growing down forming knee like structure and often re-entered the soil, while some failed to do so because of drying up of the root tip. Two plants from each group were removed from
::VIorphactin-induced negative geotropism of adventitious roots of Zea mays L.
193
the soil and the root zone washed clear of the soil showed that in treated plants roots at node 1-4/5 were positively geotropic while those at node 5-6/6-7 were negatively geotropic and very often not all roots at the same node were affected. (The coleoptile arises at node 1). The roots that grew from the root primordia after the treatment was given were affected while those that grew later at the upper nodes travelled downwards. The indole compounds that were detected in roots of both - the normal and the treated plants are: -Indole, Indole-3-acetic acid, Indole-3-butyric acid, Indole-3aldehyde, Indole-3-acetaldchyde, 3-hydroxymethyl indole, Indole-3-acetonitrile, 5-hydroxyindolyl-3-acetic acid and Tryptophan, and 5 hydroxy-tryptophan. Visual comparison of chromatoplates revealed that the amounts of six indole derivatives including IAA remained unaltered on Morphactin treatment. However, there was a marked decrease in the amount of 5-hydroxy indolyl-3-acetic acid and a slight decrease in Indole-3-acetonitrile in treated roots. On the other hand a slight increase was observed in the amount of tryptophan. VoGT (1968) working with gravity-excited root tipes of Pisum sativum after pre-treatment with chlorflurenol found a smaller absolute IAA content perhaps because of inhibition of auxin synthesis and a consequent drop in auxin level resulting without any alteration of IAA gradient. The IAA optimum and sub-optimum for the bottom and top side respectively related to cell extension growth results in a reversal of the normal growth reaction i. e. in a negatively geotropic curving of the root. We present here our finding without comment and hope to give a detailed account of biochemical studies made on the various components at a later stage. It is interesting to note that morphactin was found active on the roots of at least two plants that we have studied. In cauliflower the treatment with morphactin resulted in shoot formation on the roots and the findings could be explained on the presumption that morphactin simulated the effect of cytokininjs (ILYAS 1973). Table 1
Responses of adventitious roots of maize to morphactin treatment Morphactin concentration used (ppm) Control Control unsprayed sprayed 0 0 25
Number of ageotropic roots per plant1 ) Number of above roots becoming geotropic later
50
100
250
500
1000
0
0
0
2.0
3.0
5.0
8.0
13.0
0
0
0
1.6
2.4
4.0
6.0
11.0
1) Average of fifteen plants.
194
M. lLYAS, B. BARMA and K. K. MAGGON, Morphactin-induced negative geotropism etc.
Acknowledgements The authors are grateful to Mfs E. MERCK, Darmstadt for the sample of Morphactin, and Dr. VrRENDRA KuMAR, Dept. of Botany, Delhi College, Dr. V. P. SINGH, Secy., Univ., Garden Comm., and Prof. H. Y. MoHAN RAM, Dept. of Botany, University of Delhi for facilities and interest.
Literature BoPP, M., Ber. Deut. Bot. Ges., Vortr. Gesamtgeb. Bot., N. F. 3, 69 (1969). GopAL, S., MAGGON, K. K., VENKATASUBRAMANIAN, T. A., and MuKERJI, K. G., Bioi. Plant. 13, 396 (1971). HARADA, H., Naturwiss. 54, 95 (1967). h YAS, M., Experientia. In press (1973). KHAN, A. A., Physiol. Plant. 20, 306 (1967). KRELLE, E., and LrBBERT, E., Experientia 24, 293 (1968). ScHNEIDER, G., Ann. Rev. Plant Physiol. 21, 499 (1970). STAHL, E., KALDEWEY, H., Hoppe-Seyler's Z. physiol. chem. 3:!3, 182 (1961). 1 ) VoGT, I., Dissertation, Naturwiss. Fakultat, TH Darmstadt 1968.
1)
I) Not seen in original.
Authors' address: M. hYAS, 1250 Ballimaran, Delhi-6, B. BARMA, Biology Division, Ramjas School-1, Delhi- 6, and K. K. MAGGON, Department of Biochemistry, V. P. C. Institute, University of Delhi (India).
Short Communication
Morphactin-induced negative geotropism of adventitious roots of Zea mays L. By M. IL Y AS, B. BARMA and K. K. MAGGON (Received September 19, 1972)
Summary Morphactin (Chlorflurenol) induced adventitious roots of maize to grow upwards out of the soil, the number of such roots increased with the concentration. The effect was temporary and roots could grow downwards. The amount of Indole-3-acetic acid was not altered but that of 5-hydroxyindolyl acetic acid and Indole-3-acetonitrile decreased while that of Tryptophan increased slightly.
Introduction
Morphactins are reported to interfere with geo- and photo-tropic responses of the radicle, hypocotyl and coleoptile of certain plants (KHAN 1967; HARADA 1967; KRELLE and LIEBERT 1968; B6PP 1969). Such phenomenon could be explained on the presumption that morphactin interferes with polar transport of auxin, auxin synthesis or enzymatically controlled IAA metabolism (ScHNEIDER 1970). The present work was conducted to study the effect of morphactin (Chlorflurenol IT 3456), on th.e roots of maize in field conditions and also to study its effect on the indole compounds contained in the roots from the treated and untreated plants. Materials and methods Four week old (8-10 leaves stage) Zea mays L. var. Deccan plants raised 45 em apart in field were sprayed with an aqueous 'solution' of the morphactin. The concentrations used were 25, 50, 1:00, 250, 500 and 1000 ppm ( +0.02% Tween 80 - as surfactant). The controls - one set received only the surfactant while another set remained without spray. Fifteen plants were used for each treatment. The plants were sprayed once again after ten days. The resulting negatively geotropic roots from treated plants (500 and 1000 ppm) and pqsitively geotropic roots from the controls were collected a week after the second spray and washed with distilled water. 5 g roots from each sample were crushed and extracted with Ether and the indole compounds separated by two dimensional thin layer chromatography according to STAHL and KALDEWEY (1961). The indole compounds were ob~erved by their fluorescence in ultra violet light after spraying with formaldehyde-hydrochloric acid reagent. The indole compounds were identified by co-chromatography and ultra violet _spectra with standard indoles obtained from Sigma
192
M. ILYAS, B. BARMA and K. K. MAGGON
Fig. 1. Basal portion of a plant showing negatively geotropic roots at node six. gatively geotropic roots. PGR = Positively geotropic roots.
NGR
=
Ne-
Chern. Co., St. Louis, USA. A visual comparison of the fluorescence intensity of the spots with standards of known concentrations gave an idea of the amount of the indole compounds present in each sample as done by GoPAL et al. (1971).
Results and Discussion
Four days after the second spray the ~ntrols and plants treated with 25 ppm morphactin showed normal growth of roots, but plants treated with 50 ppm and above showed roots growing up out of the soil. The number of negatively geotropic roots increased with concentration (table 1). The crimson, thick roots continued to grow upward as long as 11 em for a week after which they started growing down forming knee like structure and often re-entered the soil, while some failed to do so because of drying up of the root tip. Two plants from each group were removed from
::VIorphactin-induced negative geotropism of adventitious roots of Zea mays L.
193
the soil and the root zone washed clear of the soil showed that in treated plants roots at node 1-4/5 were positively geotropic while those at node 5-6/6-7 were negatively geotropic and very often not all roots at the same node were affected. (The coleoptile arises at node 1). The roots that grew from the root primordia after the treatment was given were affected while those that grew later at the upper nodes travelled downwards. The indole compounds that were detected in roots of both - the normal and the treated plants are: -Indole, Indole-3-acetic acid, Indole-3-butyric acid, Indole-3aldehyde, Indole-3-acetaldchyde, 3-hydroxymethyl indole, Indole-3-acetonitrile, 5-hydroxyindolyl-3-acetic acid and Tryptophan, and 5 hydroxy-tryptophan. Visual comparison of chromatoplates revealed that the amounts of six indole derivatives including IAA remained unaltered on Morphactin treatment. However, there was a marked decrease in the amount of 5-hydroxy indolyl-3-acetic acid and a slight decrease in Indole-3-acetonitrile in treated roots. On the other hand a slight increase was observed in the amount of tryptophan. VoGT (1968) working with gravity-excited root tipes of Pisum sativum after pre-treatment with chlorflurenol found a smaller absolute IAA content perhaps because of inhibition of auxin synthesis and a consequent drop in auxin level resulting without any alteration of IAA gradient. The IAA optimum and sub-optimum for the bottom and top side respectively related to cell extension growth results in a reversal of the normal growth reaction i. e. in a negatively geotropic curving of the root. We present here our finding without comment and hope to give a detailed account of biochemical studies made on the various components at a later stage. It is interesting to note that morphactin was found active on the roots of at least two plants that we have studied. In cauliflower the treatment with morphactin resulted in shoot formation on the roots and the findings could be explained on the presumption that morphactin simulated the effect of cytokininjs (ILYAS 1973). Table 1
Responses of adventitious roots of maize to morphactin treatment Morphactin concentration used (ppm) Control Control unsprayed sprayed 0 0 25
Number of ageotropic roots per plant1 ) Number of above roots becoming geotropic later
50
100
250
500
1000
0
0
0
2.0
3.0
5.0
8.0
13.0
0
0
0
1.6
2.4
4.0
6.0
11.0
1) Average of fifteen plants.
194
M. lLYAS, B. BARMA and K. K. MAGGON, Morphactin-induced negative geotropism etc.
Acknowledgements The authors are grateful to Mfs E. MERCK, Darmstadt for the sample of Morphactin, and Dr. VrRENDRA KuMAR, Dept. of Botany, Delhi College, Dr. V. P. SINGH, Secy., Univ., Garden Comm., and Prof. H. Y. MoHAN RAM, Dept. of Botany, University of Delhi for facilities and interest.
Literature BoPP, M., Ber. Deut. Bot. Ges., Vortr. Gesamtgeb. Bot., N. F. 3, 69 (1969). GopAL, S., MAGGON, K. K., VENKATASUBRAMANIAN, T. A., and MuKERJI, K. G., Bioi. Plant. 13, 396 (1971). HARADA, H., Naturwiss. 54, 95 (1967). h YAS, M., Experientia. In press (1973). KHAN, A. A., Physiol. Plant. 20, 306 (1967). KRELLE, E., and LrBBERT, E., Experientia 24, 293 (1968). ScHNEIDER, G., Ann. Rev. Plant Physiol. 21, 499 (1970). STAHL, E., KALDEWEY, H., Hoppe-Seyler's Z. physiol. chem. 3:!3, 182 (1961). 1 ) VoGT, I., Dissertation, Naturwiss. Fakultat, TH Darmstadt 1968.
1)
I) Not seen in original.
Authors' address: M. hYAS, 1250 Ballimaran, Delhi-6, B. BARMA, Biology Division, Ramjas School-1, Delhi- 6, and K. K. MAGGON, Department of Biochemistry, V. P. C. Institute, University of Delhi (India).