Recent results in vine improvement regarding its resistance to downy and powdery mildews

  • M. P. Coutinho
  • A. Martins
Keywords: Plasmopara, oidium, biotype, variety of vine, clone, resistance, mutagenesis, irradiation, bioassay, geography, Portugal


Resistance to mildew remains very important under Portuguese conditions and induced mutations present a great interest to obtain it.
γ -rays irradiation was applied to woody material and X-ray was used on in vitro cultures of stem apexes and leaf explants. After doses up to 2000 rad, two resistant mutants were selected: with γ -rays, the resistance being expressed as surrounding necrotic patches; with X-rays, the plant coming out from in vitro culture presented small necrotic patches.
Concerning powdery mildew, we are developing new techniques for laboratorial inoculation, including a technique for sowing isolated spores. By using these, we can conduct studies on morphology and biology of the isolated colony, variability of the resistance within the rids varieties and genetic variability of the parasite. Some results concerning these areas are presented.
Section 3: Resistance/tolerance to pests and diseases