264 PYRIDOXINE AND RELATED COMPOUNDS 



X. Effects of Deficiency 

 A. IN PLANTS 



HENRY SHERMAN 



The intact green plant is generally able to synthesize adequate amounts 

 of the B vitamins so that it is independent of any external source for these 

 vitamins.^ Most species of the higher plants can grow in the light in media 

 containing only inorganic salts. At times, however, an external source of 

 the B vitamins, especially thiamine, niacin, and pyridoxine, may accelerate 

 growth. 



Individual parts of the plant, however, differ widely in their ability to 

 synthesize these \'itamins; those plant tissues which do not synthesize the 

 vitamins at an adequate rate usually obtain their supply from those parts 

 that do. Thiamine, niacin, and pyridoxine function as hormones in plants; 

 they are synthesized in one part of the plant — the leaf — and are trans- 

 ported, usually in the phloem, to those sections where they are needed.^' ^ 



Isolated roots of higher plants require thiamine, niacin, and pyridoxine 

 for growth.^ Tomato root tips have been maintained on a solution of min- 

 eral salts, cane sugar, thiamine, and pyridoxine through twenty-five suc- 

 cessive passages.^ They have also been transferred from liquid media to 

 agar cultures but only in the presence of pyridoxine.^ Isolated roots from 

 carrot, sunflower, acacia, and Jimson weed also require pyridoxine for 

 growth.' 



In the intact plant these essential vitamins are synthesized in the leaves 

 and translocated to the roots. When isolated roots are cultured in media 

 which are deficient in the above B vitamins, there is evidence of reduced 

 growth in length. Pyridoxine and thiamine deficiency also result in lowered 

 cell division activity in the root meristem.' 



There is also evidence that thiamine and pyridoxine are also involved in 

 the process of root growth in cuttings.' 



Fries^ investigated the role of pyridoxine, thiamine, and biotin in pro- 

 moting the growth of certain ascomycetes. Pyridoxine was the only vitamin 

 that was rec[uired by all the species investigated. In fact, one species, 

 Ophiostoma multiannulatum, was used with some success in determining 

 the pyridoxine content of various malt extracts. 



' J. Bonner and H. Bonner, Vitainins and Hormones 6, 225 (1948). 



2 J. Bonner, Am. J. Botany 29, 136 (1942). 



3 F. W. Went, Am. Scientist 31, 189 (1943). 



4 W. J.Rohbins and M. B. Schmidt, Proc. Natl. Acad. Sci. (U. S.) 25, 1 (1939). 

 6D. Day, Science 94, 468 (1941). 



8 N. Fries, Symlwlae Botan. Up.'ialiensis 7, 73 (1943). 



