Selection of Castanea sativa Mill. for Resistance to Phytophthora cinnamomi: Micropropagation and Testing of Selected Clones

TRAGSA conducted an exhaustive prospecting of Castanea sativa trees resistant to ink disease in Galicia. These clones were established for in vitro propagation as well as tested for resistance. From the 206 selected trees, 199 were established in vitro with variable results. 69 clones were lost after establishment, 119 clones are already in stable culture and 88 are producing acclimated vitroplants regularly. Multiplication rate is low (between 0.4 and 1.5) but rooting rate varies from 34.4 to 100% with 67% of the clones showing rooting rates higher than 70%. Acclimation reaches 97% and acclimated plants are being used for the conduction of resistance tests and the establishment of field trials. As the adult excised stem test was not repetitive, acclimated vitroplants were root inoculated and the excised shoot test was conducted on rejuvenated vitroplant stems, to find out about the influence of the ontogenical age of the material. An in vitro test was also carried out and correlation between tests was determined. Clones P011, P013, P014, P042, C004, C005, C006 and C017 are classified as resistant by the substrate inoculation test, which we consider as the most reliable. However, only P014 and C004 showed resistance in the three different tests, while clones C006, C017 and P011, were considered resistant by two of the three tests. Resistant clones will be proposed to the National Catalogue of Base Materials.