Cambial Isoperoxidases Related to Graft Compatibility in Pear-Quince Graft Combinations


Abstract: This study was initiated to survey the graft compatibility characteristics of some selected quince clones known as "S.Ö." with regard to isoperoxidase markers. Compatible (Beurre Hardy = BH) and incompatible (Bartlett = BT) pear cultivars were grafted on quince A (QA) and 13 S.Ö. quince clones by T budding. Bark tissues were collected from the union (4, 8 and 12 weeks after grafting) and from unbudded rootstocks in addition to current-year shoots of 2 pear scions to investigate 2 anodal isoperoxidase bands. Isoperoxidase profiles of the samples were visualized by native polyacrylamide gel electrophoresis and no marked difference was detected among the isoperoxidase profiles of the samples collected 4, 8 and 12 weeks after budding. Many isozyme bands were observed in common in the 2 scions. However, one anodal peroxidase (A, Rf = 0.88) was detected in BH but not in BT samples. This isoperoxidase was also detected in QA and 5 of the S.Ö. quince clones. Isoperoxidase B (Rf = 0.68) was detected in BH but not in BT or any of the rootstocks. Considering the graft union samples, all the combinations with BH contained bands A and B whereas incompatible graft union tissues (BT/QA) lacked both. Graft union samples involving BT and 5 S.Ö. quince clones (35-160, 54-298, 40-214, 58-316 and 58-315) had both isoperoxidases. The data indicated that these 5 S.Ö. quince clones might form compatible graft unions with BT.

Keywords: Quince (Cydonia oblanga), grafting, incompatibility, peroxidase, pear (Pyrus communis).

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