OXIDASE REACTION IN HEALTHY AND IN BLIGHTED 



SPINACH 



By H. H. BuNZELL, Formerly Chemical Biologist, Plant Physiological and Fermen- 

 tation Investigations, Bureau of Plant Industry 



A few years ago it was observed by Hasselbring and Alsberg (i8) that 

 spinach grown in the market gardens near Norfolk, Va., and affected 

 by a disease resembling the mosaic of tobacco, had a greater oxidase con- 

 tent than healthy spinach from the same region. This observation coin- 

 cided with the work by Woods (^o, 51) on the mosaic disease of tobacco. 

 Since that time the writer has developed a quantitative method for the 

 determination of oxidases, utilizing atmospheric oxygen (7). It was de- 

 cided therefore to extend the observations of Hasselbring and Alsberg 

 by comparing the oxidase activity of the leaves and roots of the diseased 

 plants with those of healthy plants. 



Three different collections of samples were made, designated as Set I, 

 II, and III, respectively. In each case typically diseased plants were 

 selected, as well as healthy control plants grown in the immediate vicinity 

 of the diseased spinach. In all instances, therefore, the healthy and the 

 diseased samples of the same set were grown under the same climatic 

 and soil conditions. The plants were carefully washed in the laboratory 

 to remove any adhering soil, and the surface water was removed by blot- 

 ting the plants between sheets of filter paper. The leaves, freed from 

 petioles and midribs, were dried over lime in a vacuum at room tempera- 

 ture. The roots were cut into pieces 2 to 3 mm. long and dried in a similar 

 way. The samples were dried to constant weight and then powdered 

 until the whole of the sample passed through a sieve of 100 meshes to the 

 inch, after which they were kept in a desiccator. 



The experiments were carried out according to the method formerly 

 described {10). The following reagents v/ere used: Pyrogallol, pyrocate- 

 chol, hydroquinone, phloroglucin, guaiacol, tyrosin, meta-cresol, para- 

 cresol, eugenol, and isoeugenol. The temperature at which the experi- 

 ments were carried out was 37.4° C, and the rate of shaking five com- 

 plete excursions in 3.4 seconds. 



In most of the experiments the quantity of dry material used was so 

 chosen as to give a reading of about 2 cm. In none of the experiments, 

 however, was more than o.io gm. of the powder used, so that the read- 

 ings were considerably below 2 cm. in the slightly active or inactive prepa- 

 rations. To make the results comparable, they were all calculated on the 

 basis of 0.10 gm. of powder. The reagents were used in quantities rang- 

 ing from o.oi to 0.02 gm., this being an excess of the reagent in all cases. 

 The results obtained are given in Table I. 



(377) 



