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Synergistic Effect of IAA and Kinetin in Niacin Induced Root Inhibition During Early Seedling Growth
Biochem. Physiol. Pflanzen (BPP), Bd. 164, S. 629-631 (1973) Botany Department, University of J odphur, India
Short Communication
Synergistic Effect of IAA and Kinetin in Niacin Induced Root Inhibition During Early Seedling Growth By
PRAKASH MULLICK
(Received March 26, 1973)
Summary Niacin (nicotinic acid) was found to inhibit root-growth of the seedlings of Lactuca sativa var. Cabbage, Amaranthus oleracea and Lycopersicum esculentum var. S-120. The combined action of niacin and kinetin and niacin and indole acetic acid (IAA) were studied. It was found that kinetin and IAA both in presence of niacin (500 ppm) greatly enhenced the root-growth inhibition. Thus niacin showed a marked synergism with kinetin or IAA.
The seeds of lettuce (Laduca sativa var. Cabbage), tomato (Lycopersicum esculentum var. S-120) and Amaranthus (A. oleracea) obtained from seed stores, were used in the present study. The seeds were germinated in glass petri dishes lined with filter paper and moistened with various chemical solutions alone or in combination as described below. Aqueous niacin solution of 500 ppm concentration was used in combination with 2, 5, 10 and 20 ppm of kinetin solution and 10, 25, and 50 ppm of indole acetic acid (IAA) solution. Equal amounts of combined solutions with desired concentration of each chemical were taken in petri dishes. For controls separate petri dishes were used containing either chemical solutions or distilled water alone. The mean results out of each experimental set has been recorded in the tables. All the experiments in duplicate were conducted in dark, in temperature controled chamber at 25 ± 2 C. The results in the tables (1 and 2) clearly indicate that niacin has strong inhibitory effect on the seedling-roots of the plants treated with the chemical. The seedlings grown in aquous solution of 500 ppm niacin exhibited a marked difference in their radicle length over those grown in distilled water alone. The seedling-root thus inhibited by the chemical did not show any growth in thickness and the root turns brown. However, the seedling-hypocotyl and cotyledonery leaves remain more or less unaffected by the chemical action. It would be observed from the table that the root growth inhibition by niacin in tomato was much less as compared to lettuce and 42*
630 Table 1
P.
MULLICK
Combined effect of niacin and kinetin on growth of seedling-root in dark (4 days growth, mean reading out of 5 seedlings)
Treatment
Length in mm Plant Species
L. sativa Distilled water control 35 ± 3 9± 2 Niacin (500 ppm) Niacin + Kinetin 8 ± 1 (32 ± 2) 500 + 2 ppm 7 ± 2 (25 ± 2) 500 + 5ppm 8 ± 3 (26 ± 3) 500 + 10 ppm 7 ± 2 (17 ± 2) 500 + 20 ppm
A.oleracea
L. esculentum
31 ± 2 11 ± 1.5
55 ± 3 43 ± 2
9 ± 2 (30 ± 2) 10±2(22±1) 8 ± 1 (25 ± 3) 6 ± 2 (21 ± 2)
44 42 45 43
± ± ± ±
3 (56 2 (52 4 (53 2 (51
± ± ± ±
3) 2) 3) 2)
(Result in bracket indicate kinetin control) Table 2
Combined effect of niacin and IAA on the growth of seedling-root in dark (4 days growth, mean reading out of 5 seedlings)
Treatment
Length in mm Plant Species
L. sativa Distilled water control 35 ± 3 9 ± 2 Niacin (500 ppm) Niacin + IAA 8 ± 2 (31 ± 1) 500 + 10 ppm 5 ± 2 (18 ± 2) 500 + 25 ppm 5 ± 1 (16 ± 2) 500 ± 50 ppm
A.oleracea
L. esculentum
31 ± 2 11 ± 1.5
55 ± 3 43 ± 2
5 ± 1.5 (28 ± 3) 3 ± 1 (21 ± 2) 4 ± 1 (14 ± 2)
4 ± 1 (40 ± 2) 6 ± 2 (19 ± 3) 5 ± 1 (17 ± 2)
(Result in bracket indicate IAA control)
Amaranthus. The effect of niacin on seed germination and seedling growth under various physiological conditions remain in confirmatory to our previous report (1, 2). Kinetin depresses the longitudinal growth of seedlinghypocotyl and root (7) was also observed in the present case (table 1). If kinetin was present along with niacin, greater inhibition of seedling-root over kinetin or niacin controls ",as clearly marked (table 1). The inhibition of hypocotyl part by the combined chemical activity was significantly lower in the treated seedlings. The synergistic eUed of kinetin and niacin observed in case of tomato was not so apparent as also in the seedlings treated with kinetin alone. It was interesting to note that even very low concentration of kinetin (2 ppm) present in the niacin solution (500 ppm) produced greater synergistic ,effect.
Synergistic Effect of IAA and ,Kinetin in Niacin Induced Root etc.
631
IAA is known to cause root growth inhibition (8). In the seedlings of L. sativa, A. oleracea and L. esculentum grown in 10, 25 and 50 ppm solution of IAA, the root growth inhibition was also evident (table 2). The inhibitory effect increased with the increasing concentration of IAA. When niacin was used in combination of IAA solutions, the root growth inhibition was greatly marked over those of IAA controls. Thus, niacin-IAA combination indicated a marked synergism as evidenced during the seed germination and seedling growth of lettuce, Amarantus and tomato. However percentage and germination time of the seeds treated with the combined chemical remain unaffected. The mode of action of niacin inhibition of root growth is not yet known. The possibility that niacin might disrupt the endogenous auxin levels by competing for tryptophan in the substrate induced biosynthesis has been suggested (9, 10). Here, in the present case, it might as well be postulated that niacin play some important role in regulating the endogenous auxin levels in the plants and this inhibition did not appear to be due to toxic effect of the chemical. Further, gibberellic acid is found to reverse the niacin induced root growth inhibition in lettuce (5) which goes in favour of the view postulated above. The enhanced activity of niacin inhibition of root growth in presence of kinetin or IAA might be deduced due to their common site of action. This, however, needs to be throughly investigated. Further work is in progress. Acknowledgment I am grateful to Dr. U. N. CHATTER-II for his guidance.
Literature 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
~IULLICK, P., and CHATTERJI, U. N., Curro Sci. 38, 023 (1969). - - Curr. Sci. 40, 40 (1971). - Unpublished data. SANKHLA, N., Curr. Sci. 38, 522 (1969). ~IuLLICK, P., and CHATTERJI, U. N., Experientia 27, 1163 (1971). SKOOG, F., and THIMANN, K. V., Amer. J. Bot. 04, 136 (1967). BANERJI, D., and LALORY, M. M., Plant Physiol. 42, 623 (1967). CCHADWICK, A. V., and S. BURG, S. P., Plant Physiol. 42, 415 (1967). NASON, A., Amer. J. Bot. 37, 612 (1950). HASSE, K., Encyclopedia of Plant Physiology (Ed. W. RUHLAND, Berlin 1908) Vol. 9, 177.
Auth or's address: Dr. PRAKASH MULLICK, Botany Department, University of Jodhpur, Jodhpur (India).
Short Communication
Synergistic Effect of IAA and Kinetin in Niacin Induced Root Inhibition During Early Seedling Growth By
PRAKASH MULLICK
(Received March 26, 1973)
Summary Niacin (nicotinic acid) was found to inhibit root-growth of the seedlings of Lactuca sativa var. Cabbage, Amaranthus oleracea and Lycopersicum esculentum var. S-120. The combined action of niacin and kinetin and niacin and indole acetic acid (IAA) were studied. It was found that kinetin and IAA both in presence of niacin (500 ppm) greatly enhenced the root-growth inhibition. Thus niacin showed a marked synergism with kinetin or IAA.
The seeds of lettuce (Laduca sativa var. Cabbage), tomato (Lycopersicum esculentum var. S-120) and Amaranthus (A. oleracea) obtained from seed stores, were used in the present study. The seeds were germinated in glass petri dishes lined with filter paper and moistened with various chemical solutions alone or in combination as described below. Aqueous niacin solution of 500 ppm concentration was used in combination with 2, 5, 10 and 20 ppm of kinetin solution and 10, 25, and 50 ppm of indole acetic acid (IAA) solution. Equal amounts of combined solutions with desired concentration of each chemical were taken in petri dishes. For controls separate petri dishes were used containing either chemical solutions or distilled water alone. The mean results out of each experimental set has been recorded in the tables. All the experiments in duplicate were conducted in dark, in temperature controled chamber at 25 ± 2 C. The results in the tables (1 and 2) clearly indicate that niacin has strong inhibitory effect on the seedling-roots of the plants treated with the chemical. The seedlings grown in aquous solution of 500 ppm niacin exhibited a marked difference in their radicle length over those grown in distilled water alone. The seedling-root thus inhibited by the chemical did not show any growth in thickness and the root turns brown. However, the seedling-hypocotyl and cotyledonery leaves remain more or less unaffected by the chemical action. It would be observed from the table that the root growth inhibition by niacin in tomato was much less as compared to lettuce and 42*
630 Table 1
P.
MULLICK
Combined effect of niacin and kinetin on growth of seedling-root in dark (4 days growth, mean reading out of 5 seedlings)
Treatment
Length in mm Plant Species
L. sativa Distilled water control 35 ± 3 9± 2 Niacin (500 ppm) Niacin + Kinetin 8 ± 1 (32 ± 2) 500 + 2 ppm 7 ± 2 (25 ± 2) 500 + 5ppm 8 ± 3 (26 ± 3) 500 + 10 ppm 7 ± 2 (17 ± 2) 500 + 20 ppm
A.oleracea
L. esculentum
31 ± 2 11 ± 1.5
55 ± 3 43 ± 2
9 ± 2 (30 ± 2) 10±2(22±1) 8 ± 1 (25 ± 3) 6 ± 2 (21 ± 2)
44 42 45 43
± ± ± ±
3 (56 2 (52 4 (53 2 (51
± ± ± ±
3) 2) 3) 2)
(Result in bracket indicate kinetin control) Table 2
Combined effect of niacin and IAA on the growth of seedling-root in dark (4 days growth, mean reading out of 5 seedlings)
Treatment
Length in mm Plant Species
L. sativa Distilled water control 35 ± 3 9 ± 2 Niacin (500 ppm) Niacin + IAA 8 ± 2 (31 ± 1) 500 + 10 ppm 5 ± 2 (18 ± 2) 500 + 25 ppm 5 ± 1 (16 ± 2) 500 ± 50 ppm
A.oleracea
L. esculentum
31 ± 2 11 ± 1.5
55 ± 3 43 ± 2
5 ± 1.5 (28 ± 3) 3 ± 1 (21 ± 2) 4 ± 1 (14 ± 2)
4 ± 1 (40 ± 2) 6 ± 2 (19 ± 3) 5 ± 1 (17 ± 2)
(Result in bracket indicate IAA control)
Amaranthus. The effect of niacin on seed germination and seedling growth under various physiological conditions remain in confirmatory to our previous report (1, 2). Kinetin depresses the longitudinal growth of seedlinghypocotyl and root (7) was also observed in the present case (table 1). If kinetin was present along with niacin, greater inhibition of seedling-root over kinetin or niacin controls ",as clearly marked (table 1). The inhibition of hypocotyl part by the combined chemical activity was significantly lower in the treated seedlings. The synergistic eUed of kinetin and niacin observed in case of tomato was not so apparent as also in the seedlings treated with kinetin alone. It was interesting to note that even very low concentration of kinetin (2 ppm) present in the niacin solution (500 ppm) produced greater synergistic ,effect.
Synergistic Effect of IAA and ,Kinetin in Niacin Induced Root etc.
631
IAA is known to cause root growth inhibition (8). In the seedlings of L. sativa, A. oleracea and L. esculentum grown in 10, 25 and 50 ppm solution of IAA, the root growth inhibition was also evident (table 2). The inhibitory effect increased with the increasing concentration of IAA. When niacin was used in combination of IAA solutions, the root growth inhibition was greatly marked over those of IAA controls. Thus, niacin-IAA combination indicated a marked synergism as evidenced during the seed germination and seedling growth of lettuce, Amarantus and tomato. However percentage and germination time of the seeds treated with the combined chemical remain unaffected. The mode of action of niacin inhibition of root growth is not yet known. The possibility that niacin might disrupt the endogenous auxin levels by competing for tryptophan in the substrate induced biosynthesis has been suggested (9, 10). Here, in the present case, it might as well be postulated that niacin play some important role in regulating the endogenous auxin levels in the plants and this inhibition did not appear to be due to toxic effect of the chemical. Further, gibberellic acid is found to reverse the niacin induced root growth inhibition in lettuce (5) which goes in favour of the view postulated above. The enhanced activity of niacin inhibition of root growth in presence of kinetin or IAA might be deduced due to their common site of action. This, however, needs to be throughly investigated. Further work is in progress. Acknowledgment I am grateful to Dr. U. N. CHATTER-II for his guidance.
Literature 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
~IULLICK, P., and CHATTERJI, U. N., Curro Sci. 38, 023 (1969). - - Curr. Sci. 40, 40 (1971). - Unpublished data. SANKHLA, N., Curr. Sci. 38, 522 (1969). ~IuLLICK, P., and CHATTERJI, U. N., Experientia 27, 1163 (1971). SKOOG, F., and THIMANN, K. V., Amer. J. Bot. 04, 136 (1967). BANERJI, D., and LALORY, M. M., Plant Physiol. 42, 623 (1967). CCHADWICK, A. V., and S. BURG, S. P., Plant Physiol. 42, 415 (1967). NASON, A., Amer. J. Bot. 37, 612 (1950). HASSE, K., Encyclopedia of Plant Physiology (Ed. W. RUHLAND, Berlin 1908) Vol. 9, 177.
Auth or's address: Dr. PRAKASH MULLICK, Botany Department, University of Jodhpur, Jodhpur (India).