INHERITANCE AND GENETIC-MAPPING OF SELF-INCOMPATIBILITY IN COFFEA-CANEPHORA PIERRE

Cross-compatibility behaviour of doubled haploid (DH) and hybrid genot ypes of Coffea canephora was established using both phenotypic bioassa y and in situ seed-set examination. The availability of DHs provided t he opportunity of working with genetically homogenous pollen and femal e parents. The aniline blue fluorescence (ABF) method was applied to d etect callose accumulation in pollen and pistil. Clear cross-compatibi lity/incompatibility situations were observed and confirmed by in situ seed-set analysis. Cross-compatibility analysis of hybrid combination s involving different DHs corroborated the crossing behaviour observed at the DH level. Expression of the self-incompatibility system did no t appear to be affected by the low vigour of the DH. The crossing-beha viour distribution observed within DHs derived from clone IF200 confir med that self-incompatibility in C. canephora is a gametophytic self-i ncompatibility system controlled by a single locus (S-locus). Reduced seed-set developments following incompatible crosses may indicate the occurrence of pseudo-incompatibility. Molecular marker linkage analysi s showed that the S-locus is associated with an RFLP marker on linkage group 9. The availability of a linked DNA marker should facilitate th e genetic analysis of self-incompatibility in relation to coffee breed ing programmes.