Vitamin B6 and Growth of Excised Tomato Roots in Agar Culture

Further Evidence on the Significance of Glycine, Pyridoxine and Nicotinic Acid in the Nutrition of Excised Tomato Roots

“…Robbins and Schmidt (1939b, see also 1939a, 1939cRobbins, 1942) concluded that "Pyridoxine is the second growth requirement of excised tomato roots" (in addition to thiamin) in a nutrient salt-carbohydrate medium. Day (1941) and Bonner and Devirian (1939) support this conclusion, and Bonner (1940) has presented evidence that glycine is without bene-1 Received for publication September 18,194'2. ficial effect on several clones of tomato roots, but that nicotinic acid is an additional growth requirement for normal development of certain clones. Robbins andSchmidt (1939a, 1939c) found no beneficial effect from nicotinamide or nicotinic acid on one clone of tomato roots, but Robbins (1941) later demonstrated such an effect of nicotinamide on three other clones of tomato roots.…”

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

“…All glassware was pyrex glass which, except for the Petri dishes, was cleaned with chromic acid 1 Received for publication October 16, 1949. A preliminary note on these experiments has been published (Day, 1941).…”

“…1, table 1). The relatively good growth of the earlier roots in the basal medium without added thiamine was unexpected and became the starting point for a series of assays with Phycomyce,v which showed that this agar contained appreciable amounts of thiamine (Day, 1942). When similar agar purified with pyridine was substituted in media of the same composition, roots in the basal medium elongated 1.0 millimeter or less after the third passage (27 days) and not at all after the sixth passage (55 days).…”

“… White (1940) has called attention to errors which may be caused by carelessness in methods of cleaning glassware.S The inoculum for experiments reported here was from roots grown for 57, 61 or more passages, not 47 as previously stated(Day, 1941).…”