ISHS Acta Horticulturae 227: International Symposium on Vegetative Propagation of Woody Species
PEACH/PLUM GRAFT INCOMPATIBILITY: STRUCTURAL, PHYSIOLOGICAL AND GENETIC ASPECTS |
| Authors: | A. Moing, G. Salesses |
| Abstract:
Graft incompatibility is frequently revealed in combinations such as nectarines grafted on 'Damas GF 1869' plum, or peaches grafted on most of the myrobolan clones. These cases, described as "translocated" graft incompatibilities, have been studied for several years at the Fruit Breeding Station of Bordeaux. Although no definitive conclusions can be established at present, an assessment of the research undertaken at Bordeaux is presented. As far as peach/'Damas GF 1869' combination is concerned, a histological study was realized on the phloem of grafts, failing to reveal the presence of any necrosis, and a genetic study among peach genotypes demonstrated a digenic determinism for incompatibility. As far as peach/myrobolan plum combinations are concerned, a more precise structural study was undertaken on the stem bark of scions and rootstocks, revealing an early stop of cambial activity and a relative reduction of the number of sieve tubes localized in the rootstock of incompatible combinations. The physiological aspects studied mainly concerned the carbohydrate composition of phloem, and phloem functioning estimated with labelled deoxyglucose. A slowing-down of the assimilate transport in the phloem was shown, without any blockage at the union point. The genetic determinism of incompatibility within myrobolan genotypes is still being studied. The study of hybrids between different myrobolan clones revealed some variability of compatibility behaviour with different peach genotypes, in accordance with the involvement of more than two incompatibility genes in myrobolan genotypes. The relations between structural and physiological aspects, the physiological basis of the determinism and the relations between gene products and physiological modifications are discussed. | |
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