HISTOCHEMICAL STUDIES 

 OF THE ENZYMES OF THE ROOT EPIDERMIS 



CHARLOTTE J. AVERS 



Dept. of Biology, Douglass Collège, Rutgers — The State University, 

 New Brunswick, New Jersey, U.S. A. 



Enzyme activities in Phleum hâve been correlated with development of 

 hair and hairless cells of the tissue. The apical meristem initiais were 

 diffère ntiall y active for succinic dehydrogenase and adenosine mono- 

 phosphatase, but were equally active for other enzymes studied. Once the 

 cells had left the meristera and entered the zone of elongation, both cell 

 types showed no activity for thèse two enzymes, but were differentially 

 active for acid phosphatase and cytochrome oxidase. Peroxidase activity 

 differentiated thèse cells later as they prepared to mature morphologically. 

 Only a few of the most apical cells showed glucose-6-phosphatase activ- 

 ity, and this enzyme did not appear to be active in mitotic or rapidly 

 elongating cells of Phleum, whereas there was activity in other grasses 

 studied. Thèse enzyme activities apparently characterized the two kinds 

 of epidermal cells at various stages of their development, and appeared 

 long before morphological maturation and the end of elongation. The 

 intracellular localizations were particulate or non-particulate in agreement 

 with localizations obtained by other techniques. Enzyme localizations 

 in meristem cells were also obtained for adenosine triphosphatase, dehydro- 

 genases, and an esterase, in addition to those studied for their distribution 

 in the several developmental zones of the root epidermis. 



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