Carrots irradiation

Increased Concentration of Myristicin and 6-Methoxymellein in Carrot Root upon Irradiation... 

In the following experiments carrot roots were exposed to various sources of ultraviolet light in the laboratory and set aside to allow time for enzyme synthesis. Following this period, changes in myristicin and phytoalexin levels were measured. All of these components of carrot root are measured in one assay. Myristicin and 6-methoxymellein concentrations increased in some samples after irradiation with ultraviolet light falcarinol and falcarindiol concentration changes did not appear to be related to the ultraviolet light used in this study. 

Preliminary experiments, using a container with reflective surfaces, employed light from eight fluorescent bulbs that produced a preponderance of radiation at 310 nm. Myristicin increased in samples that were irradiated 1 h and then kept for a 24-h induction period. However, heat produced by this system and the resulting dehydration of carrot roots may have affected results. Later experiments, employing a Chromato-Vue box used for ultraviolet examination of TLC plates, avoided these problems. One-hour light... 

Table I. ( Changes in Carrot Root Myristicin Irradiated One Hour with Ultraviolet Light and 6-Methoxymellein ...

Figure 3. Oxygen consumption and carbon dioxide evolution from carrots during 18-hour irradiation...

A number of studies concerned with the effect of irradiation upon intermediary metabolism in carrots have been conducted. One such study utilizing the methods of Ap Rees and Beevers (1,2) involved measuring the relative radiation susceptibility of the pentose phosphate (PP) and the Embden-Meyerhof (EM) systems in the postirradiation period. 

Table II. Influence of Metabolic Inhibitors on Rate of Oxygen Consumption of Irradiated and Nonirradiated Carrot Disks with and without Preincubation with Glucose...

Intermediary metabolism of irradiated tissues was examined to attempt to explain the increased respiration on the basis of biochemical mechanics. In these experiments carrot disks 0.5 mm. thick were prepared as before and subjected to substrate utilization studies (9). This involved incubating the slices with the appropriately labeled substrate in 0.03M phospate buffer at 25°C. The incubation involves shaking with gentle aeration and trapping the respired CO2 in alkali. Following incubation the slices were removed, washed, ground with 80% ethanol, and filtered, and both the filtrate and residue were assayed for radioactivity. Thus, a measure of substrate absorption and utilization was determined. 

Yates, S. G., Increased concentration of myristicin and 6-me-thoxymellein in carrot root upon irradiation with UV light, in Allelochemicals Role in Agriculture and Forestry (G. R. Waller, ed.), ACS Symposium Series 330, 295-299, American Chemical Society, Washington, DC, (1987). 

After testing at the NRC, the mobile irradiator was exhibited at agricultural events around Ontario. A story that has circulated in CPD told of a farmer who stopped to watch it just after carrots had been substituted for potatoes in the machines produce bins. The potatoes were still coming out as the carrots went in. He told the CPD staff... 

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