Agronomie 10 (1990) 525-532
DOI: 10.1051/agro:19900702

L'incompatibilité pollinique chez le clémentinier : observation in vivo de la croissance des tubes polliniques

D. Tisne-Agostini and A. Orsini

INRA, station de recherche agronomique, San Giuliano, 20230 San Nicolao, France

Résumé - L'étude comparative du processus de la fécondation chez 3 clones aspermes de clémentinier (Citrus reticulata Blanco) par l'observation de la croissance des tubes polliniques in vivo, a permis de confirmer l'existence d'anomalies, non pas au niveau des relations stigmate-pollen, mais au niveau des relations style-tubes polliniques, laissant supposer la présence d'un système d'auto-incompatibilité pollinique de type gamétophytique. L'arrêt des tubes polliniques, rendus visibles par la microscopie en fluoresence, intervient généralement dès le premier tiers du style, bien que certains d'entre eux parviennent jusque dans les tissus ovariens. Ceci permet d'attribuer un caractère partiel au phénomène mis en cause. De plus l'appréciation, par le biais d'un indice, de la compatibilité intra- et intervariétale des quelques cultivars étudiés laisse apparaître des degrés variables d'affinités.

Abstract - Studies on the fertilization process in the clementine: observations on pollen tube growth in the styles. Since seedless clementine (Citrus reticulata Blanco) is supposed not to have a normal fertilization process 3 varieties were studied in regard to the type of incompatibility and their ability in intercrosses. A comparison was first made between seedless SRA 85 clementine and seeded Wilking mandarin: pollen germination on stigmata (fig 1), rate of pollen tube growth and tube evolution in the styles (fig 2) were studied using fluorescent microscopy. It was shown clearly for autofertilized SRA 85 that pollen tubes were stopped by callose in the first third of style (fig 3). Crosses between 3 varieties, Corsica 2, Oroval, SRA 85 were then examined and very limited affinity for each other (fig 8). Estimation of affinity was made by a calculated index (IPC) for each cross. Main IPC values were under a quarter of the optimal index reached for a simulated total compatible cross. It was concluded that the normal fertilization process cannot take place in the seedless clementine because of a gametophytic incompatibility. Nevertheless, it is only partial; some flowers can be fertilized with success at a certain stage, to be defined by further studies.

Key words: Citrus reticulata Blanco / fluorescent microscopy / self-fertilization / callose / gametophytic incompatibility

Mots clés : Citrus reticulata Blanco / autofécondation / microscopie en fluorescence / callose / auto-incompatibilité gamétophytique