The Effect of Different Iron and Manganese Nutrient Levels on the Catalase and Cytochrome Oxidase Activities of Green and Albino Sunflower Leaf Tissues.

Abstract

PLANT PHYSIOLOGY ner (7). Theorell (23) reported that such a substitution eliminated all peroxidatic activity. It has been reported that activities of the enzymes catalase and peroxidase are related to the presence in plant tissues of photoreceptive pigments such as chlorophyll (6) and flavines (5). Catalase seems to be involved in photosynthesis (6) and peroxidase in the light-activated indoleacetic acid oxidase system in peas (5). To study the effect of different levels of iron and manganese nutrition on the activity of iron-containing enzymes of chlorophyll-deficient and chlorophyll-bearing tissues, albino as well as green plants were employed in the present studies. MATERIALS AND METHODS In order to continue the active growth of chlorophyll deficient leaf tissue during the experimental period albino scions were grafted into the stems of plants having green leaves. Green and albino seedlings of Russian sunflower (Helianthus annuus L.) seeds2 which originated as a result of mutations induced by ultrasonic vibrations (29, 30), were used in these experiments. Green seedlings used for stock plants to which green and albino scions were grafted were siblings from an earlier generation of the originally treated seeds. Seeds for the green stock plants were sown on September 30, 1952, and seeds for the albino seedlings were sown 20 days later in white quartz sand. The normal seasonal daily sunlight period was extended to 16 hours with incandescent light. A minimum intensity of about 6 fc was provided. Soon after the albino and green seedlings from the second sowing emerged from the sand, they were cleft-grafted, one per plant, into the apical portions of the stems of the older green sunflower stock plants. Both albino and green seedlings were grafted into the green stock plants in order to provide albino and green tissues which were produced under as similar conditions of growth as possible. During the period from No-vember 5th to 13th, 55 albino and 34 green seedlings 2Seeds were provided through the courtesy of Dr. were grafted. Twenty-seven albino and 24 green grafts united successfully. The grafted plants were placed in culture solutions on December 12th. The culture vessels were one-gallon wide-mouth glass jars, each containing two albino-grafted plants and one green-grafted plant. Composition of the nutrient solution used is given as follows: Macronutrient salts-0.001 M KH2PO4, 0.0045 M Ca(NO3)2 *4 H20, 0.002 M MgSO4-7 H20, 0.0015 M K2SO4, and 0.0013 M HNO3; micronutrient elements -0.10 ppm Zn, 0.10 ppm B, 0.01 ppm Cu, and 0.01 ppm Mo. During the eight-day period prior to the initiation of the different iron and manganese nutrient levels, the concentrations of iron and manganese supplied was 0.20 ppm and 0.05 ppm, respectively , in all cultures. When the different nutrient treatments were started, concentrations of 0.001 ppm, 0.25 ppm, and 10.0 ppm were chosen as the low, adequate , and high levels of each element, respectively. Plants grown with a level of 0.25 ppm of both elements will be referred to as control plants. These nutrient levels together with the nutrient ratios of iron to manganese are given in table I. All nutrient salts were of reagent grade. Stock solutions of macro-nutrient salts were purified by the alkaline adsorption method of Stout and Arnon (22), followed by further purification with dithizone and carbon tetrachloride (15). All nutrient solutions were prepared with de-ionized water which had a specific resistance immediately after deionization of from 11 to 15 megohms. Cultures receiving a nutrient level of either low iron, high manganese, or an adequate level of both elements were run in triplicate, and those receiving a nutrient level of high iron or of low manganese were run in duplicate. The nutrient solutions were renewed twice weekly by complete replacement. Albino and green leaf tissues for catalase and cyto-chrome oxidase activity determinations were removed from the grafted scions at desired times after distinct leaf symptoms associated with different nutrient levels of iron and manganese became apparent. Activity determinations were carried out over a period of about 30 days. A final harvest of grafted scions was made on February 3, 1953. Aliquots of leaf tissue were dried in a forced-draft oven at 700 C for the TABLE I