The new inspections RE SEARCH As two analyses are possible from one slice of seed potato, and the staff in the ‘cutting room’ also take a sample for brown and ring rot at the same time, fewer people are needed than before. All the cutting can now take place in one locality, whereas previously two localities were necessary. Because of the combined brown and ring rot testing, this now also complies with the necessary quarantine requirements. The new space also has much more lighting for better visibility when at work. Despite all these measures, concentration can sometimes flag. And that is why there is always a follow-up check of the cuttings. These checks - by a specially-appointed inspector - include confirming whether the slices have been neatly removed around the navel end and whether the removal of the samples for brown and ring rot was satisfactory. 5 7 With a pipette, a laboratory technician then puts the juice from the blenders manually into a well plate with 96 wells. A single well is filled with fluid from each blender, consequently four wells are filled from each sample. Each well plate therefore contains the sample fluid from 24 samples. The laboratory technician not only fills the wells in the well plate, but also those of a digital version with 96 coloured rounds. Red means full, green means empty. Each filled red round is also linked to all the relevant data of the sample, so that this is now digitally stored for any further steps in the test. The juice for the Erwinia test is put in temperature-controlled storage for three days. Any existing bacteria can then continue to develop, which is necessary for a more reliable DNA result. The potato tops intended only for virus testing can go straight to the RNA isolation. 6 All the cuttings are subsequently sent to the laboratory. The tops, which are necessary for the virus test (and possibly for the Erwinia test) are first deep frozen. They are then ground in a blender. To be able to process each complete sample from a seed potato grower at the same time, there are four blenders. There are 50 slices in each blender, the total contents of each plastic bag, making a total of two hundred, the number of tubers of a complete sample. Potato World 2014 • number 1 19 Pagina 18
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