Mol Gen Genet (1995) 247:693-697 @ Springer-Verlag 1995 Guido Cipriani • Raffaele Testolin • Michele Morgante Paternal inheritance of plastids in interspecific hybrids of the genus Actinidia revealed by PCR-amplification of chloroplast DNA fragments Received: 11 October 1994 / Accepted: 27 January 1995 Abstract RFLPs (restriction fragment length polymor- phisms) of PCR (polymerase chain reaction) -amplified fragments were used to trace the pattern of plastid DNA inheritance in the genus Actinidia. A total of 51 progeny originating from interspecific crosses between three A. arguta cultivars and A. deliciosa, the kiwifruit, and 12 progeny originating from the cross between A. kolomikta and A. chinensis were analysed together with their par- ents. No reciprocal crosses could be tested since they all failed to set viable seeds. Attempts to rescue immature embryos failed in all cases as well. The A. argutaXA. deliciosa crosses were checked for the RFLP patterns of a sequence encoding part of the Rubisco large subunit (rbcL), using either AluI or MseI, and for a sequence encoding part of the photosystem II D1 protein (psbA), using Hinfl. The A. kolomikta×A, chinensis cross was checked for the RFLP patterns of sequences encoding the spacers between trnT and the 5'-trnL exon (a-b spacer DNA) and the trnL 3' exon and trnF (e-f spacer DNA), respectively. The first spacer revealed a natural polymor- phism between the two parent species due to a large dele- tion occurring in A. kolomikta detectable without further restriction enzyme treatment. The e-f spacer DNA was digested with HinfI. The comparison of the RFLP pat- terns in the parents and their progeny showed a strictly paternal inheritance of chloroplast DNA in Actinidia, with no exception found in any of the crosses examined. As the reciprocal crosses were not available, we do not know whether paternal inheritance of plastids is restrict- ed to the crosses we analysed or if this is the general rule for plastid inheritance in the genus Actinidia. Actinidia is dioecious and is the first purely outbreeding species for which a paternal plastid inheritance has so far been documented. Communicated by R. Hagemann G. Cipriani (~) • R. Testolin • M. Morgante Dipartimento di Produzione vegetale e tecnologie agrarie, University of Udine, Via delle scienze 208, 33100 Udine, Italy Key words Kiwifruit • Chloroplast inheritance • Organelle inheritance • PCR-amplified fragments • Chloroplast RFLPs Introduction Plastids are maternally inherited in most angiosperms (Corriveau and Coleman 1988), whereas among gym- nosperms they are known to be derived largely from the paternal parent (Stine et al. 1989; Wagner et al. 1992). The most common mechanisms leading to the maternal inheritance of plastids among angiosperms are based on the exclusion/degeneration of plastids during pollen de- velopment (Hagemann 1992). Such mechanisms account for maternal inheritance of plastids into 73 % (Harris and Ingram 1991) to 86% (Corriveau and Coleman 1988) of angiosperm species. There are many exceptions in both angiosperms and gymnosperms, as can be seen from the substantial body of literature on the topic. Among angiosperms, for instance, a biparental inher- itance of plastids has been documented in many species (reviewed in Kirk and Tilney-Bassett 1978; Sears 1980), although it seems in many cases to be a rare or transient event occurring in the early phases after fertilisation (re- viewed in Reboud and Zeyl 1994). In Medicago sativa plastid inheritance has been demonstrated to be either strongly maternal or paternal depending on the geno- types involved in the cross (Schumann and Hancock 1989; Forsthoefel et al. 1992; Zhu et al. 1993). Plastid inheritance that depends on the genotypes involved in the cross, with differences even between reciprocal crosses, has been described for Zantedeschia (Yao et al. 1994) and the Stellaria longipes complex (Chong et al. 1994). There is also evidence for uniparental paternal inheritance of plastids in interspecific hybrids within the genus Daucus (Boblenz et al. 1990). Exceptions have also been reported for gymno- sperms, where a biparental inheritance of plastids has been reported for Cryptomeria japonica (Ohba et al.