A new,efficient method using 8-hydroxy-quinolinol-sulfate for the initiation and establishment of tissue cultures of apple from adult material

Applying the new method for culture initiation 16 different cultivars of Malus domestica could be established in vitro from shoot tips of adult orchard trees. Actively growing shoot tips were cleaned and surface disinfested, dissected to 2–3 mm and placed on a modified MS-medium with 4.4 M BA. Explants were covered for 24 h with 200 l of a 0.1% solution of 8-hydroxy-quinolinol-sulfate (8-HQS) and transferred to a medium containging both auxin and cytokinin after 2 weeks. The application of 8-HQS induced a strong reduction of the infection rate and inhibited the browning of the explants and the media. After 7 days yields of 50–90% sterile explants could be obtained in comparison to 100% losses of untreated shoot tips. After 60 days variable rates of actively growing shoots could be observed, depending on the genotypes. The described method allows a successful establishment of fruit trees from adult orchard material on one hand by strongly reducing the browning, caused by the oxidation of polyphenolic compounds by polyphenoloxidases, and on the other hand 8-HQS can strongly increase the yield of explants without contamination, independently from the vegetation period and the phytosanitary state of the donor material.Abbreviations BA 6-benzyladenine - IBA indolebutyric acid - 8-HQS 8-hydroxy-quinolinol-sulfate