The resistance of lettuce to the aphid Nasonovia ribisnigri

摘要: The resistance of lettuce to the aphid Nasonovia ribisnigri is based on a single, dominant gene, Nr-gene. On resistant plant aphids died within few days, without any honeydew production. Transfer-experiments with short stay followed by relocation susceptible showed that no weight increase occurred plant, but gain immediately resumed (Chapter 2). So intoxication seemed occur plant. Behavioral observations (tethered) using Electrical Penetration Graphs (EPG) 3) and comparison free living 4) aphid's stylets did penetrate phloem sieve elements. plants hardly E2 pattern (phloem sap ingestion) finally malnutrition, or left 4). It was concluded factor in phloem. This can be either chemical like feeding deterrent mechanical which obstructs ingestion. Experiments concentrated differences (isogenic apart from gene) lines. Amputation (stylectomy) during yield small pure samples. However, isogenic lines samples could collected because outflow stylet stump stopped after seconds. Larger were obtained EDTA chelation collection 5). Chemical analysis composition sugars, amino acids, proteins UV absorbing compounds 6). Exhaustive not feasible, only number possible compounds, also sample size quantity limited. In bioassay offered choice between plants, added complete artificial diet (chapter 7). Aphids clear aversion extract suggests presence deterrents Hopefully, these substances isolated identified help bioassay.