THE CHEMICAL INDUCTION OF GROWTH 

 IN PLANT TISSUE CULTURES! 



F. C. Steward and E. M. Shantz 

 Department of Botany, Cornell University 



Part I: Methods of Tissue Culture and the Analysis of Growth 



introduction: normal proliferative growth in the plant body 

 Before taking note of various chemical substances and extracts that are 

 capable of inducing rapid, proliferated growth in otherwise mature plant 

 tissues, it is well to take note of a few salient examples in which this occurs 

 normally in the plant body. 



The classical example, noted by Fitting (1910), in which pollination in 

 the orchid stimulates the growth of the pistil or ovai-y wall, is well known. 

 In the development of the coco-nut fruit the embryo is usually immature 

 when the fruit falls to the ground. When the embryo eventually germinates 

 it sends out into the central cavity containing liquid endosperm a cotyledon 

 which acts as an absorbing organ and rapidly produces a cellular tissue 

 capable of filling the entire cavity of the fruit. 



The stimulation which pollination and fertilization gives to the development 

 of the fleshy tissue of pome fruits is well known. There are also cases, e.g. 

 the edible banana, in which, under certain genetical situations, a fleshy layer 

 develops without this stimulus and grows parthenocarpically by cell division 

 and proliferation from a well-defined loculus in the fruit. The numerous cases 

 now known of parthenocarpically induced development of fruits give point 

 to the chemical basis of this stimulus to growth. 



While the formation of tubers and tuberization and the development of 

 other storage organs, whether roots or bulbs, is often a response to length of 

 day, this stimulus must be communicated to the cells in question by some as 

 yet unknown chemical means. 



Galls, whether activated by bacteria, by insects, or by viruses, again 

 induce in otherwise mature cells a return to active growth and proliferation. 

 The formation of nodules, which grow on legumes, is yet another familiar 

 example of chemically induced growth in the tissues of the host. 



In other words, although the following account will concentrate upon 

 certain phenomena in which this general type of process may be studied in 

 plant tissue cultures, there are many examples that can be cited in which 

 similar phenomena occur normally in the development of plants. 



The roison d'etre of the investigations to be described was, however, not 

 wholly the attempt to understand the chemical basis for growth induction. 

 It was rather to use the chemical means by which growth may be so induced 

 to contrast the behaviour of rapidly growing and non-growing or resting 

 cells. For this reason attention was turned to the use of tissue culture methods 



t This paper was read at the Conference by F. C. Steward. 



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