Specificity of Nicotinic Acid as a Growth Factor For Isolated Pea Roots1

Abstract

It is known that nicotinic acid is essential to the growth of numerous species of isolated roots (ADDICOTT and BONNER, 1, BONNER and DEVIRIAN, 4). The present paper is concerned with the chemical specificity of nicotinic acid as a root growth factor. Methods The pea roots (variety Perfection) which were used exclusively in the present experiments were cultured according to the methods outlined in earlier papers (BONNER and ADDICOTT,3; BONNER and DEVIRIAN, 4). Fourmm. tips were cut from the roots of aseptic pea seedlings and transferred to nutrient medium containing per liter of redistilled water 236 mg.Ca (NO3)2 4H20; 36 mg. MgSO4 7H20; 81 mg. KNO3; 65 mg. KCl; 20 mg. KH2P04; 1.5 mg. ferric tartrate; and 40 gm. of sucrose. After the tips had remained in the medium for one week at 250 C., and had grown into roots several cm. long, they were subcultured by tranferring 1-cm. tips to fresh nutrient solution. This process of subculture was repeated weekly. Vitamin B1, which is essential to the continued growth of isolated pea roots, was added at the rate of 0.1 mg. per liter to all of the nutrient solution for transfers later than the first. Nicotinic acid, or related substance to be tested for ability to replace nicotinic acid, was added at the rate of 0.5 mg. per liter, sinee this concentration has been found to be approximately optimal for pea roots (ADDICOTT and DEVIRIAN, 2).A rigid selection for uniformity in root growth rate was carried out at the end of the first week of culture in order to assure the greatest possible uniformity in the roots actually used in each experiment. In a single experiment 400-500 roots were cultured and 20-50 roots were used for testing the activity of each substance reported below. In each experiment the roots were maintained through 5 or more weekly transfers. ExperimentationThe ability of decreasing concentrations of nicotinic acid to support the continued growth of isolated pea roots is shown in figure 1. Although 0.5 y nicotinic acid per liter of nutrient solution supports modest growth, a ten times higher concentration is needed to support growth at a significant level. Still ten times higher concentration (50 y per liter) supports growth

Growth of Excised Tomato Roots in Agar with Thiamine Plus Pyridoxine, Nicotinamide or Glycine

“…The observation of no further response of these tomato roots to nicotinamide in agar with pyridoxine and thiamine confirmed the earlier evidence of Robbins and Schmidt (1939b) for the same strain of tomato grown in liquid culture with the same three substances. These results were also similar to those of Bonner (1940b) for carrot and to those of White (19,10) who found nicotinic acid of no benefit to tomato when it was used with thiamine. On the other hand nicotinic acid or nicotinamide has been found to be an effective supplement to thiamine or to thiamine and pyridoxine for the growth of excised roots of pea, radish, tomato (Bonner and Devirian, 1939), pea (Bonner, 1940a), alfalfa, clover, cotton, tomato, Datura, sunflower (Bonner, 191Ob) and Acacia (Bonner, 1942).…”

“…The comparatively luxuriant growth of these tomato roots when pyridoxine was added as a further supplement to thiamine in the mineral-sugar-agar medium agreed with the earlier work of Robbins andSchmidt (1939a, 1939b), of Bonner and Devirian (1939), of Bonner (1940bBonner ( , 1942, and of Robbins (1941Robbins ( , 1942. White (1940) failed to obtain any benefit in the growth of excised tomato roots when he used pyridoxine with or without thiamine.…”

“…The growth of excised roots in synthetic media with or without known growth substances has been reviewed by White (1912). Most of the experiments with excised roots have made use of a liquid culture medium, but Robbins (1922a), Bonner and Addicott (1937), Bonner (1938), McClary (19 W) and others have employed agar to solidify the nutrient solution. It was hoped that this study on growth of excised tomato roots on agar might check some of the earlier work and that it might answer some of the questions unsolved by growth of roots in solution cultures.…”

Rhizobium sp. strain ORS571 grows synergistically on N2 and nicotinate as N sources

“…Nicotinate or its derivatives would play this dual metabolic role. The P. sativum vascular nicotinate supply has been estimated at 3 ,uM at steady state (2). Were this available in S. rostrata, ORS571 growth requirements would be satisfied.…”

“…Nicotinate is a legume root growth factor; it is synthesized in Pisum sativum leaves and is systemically transported (2). Because the S. rostrata vascular tissue impinges on developing nodules, transported nicotinate is, in theory, available for nodular processes.…”