Paternal inheritance of chloroplast DNA in interspecific hybrids in the genus Larrea (Zygophyllaceae)

The mode of chloroplast DNA (cpDNA) inheritance was investigated in the gen us Larrea (Zygophyllaceae) by polymerase chain reaction (PCR) amplification of cpDNA fragments using three pairs of chloroplast universal primers. A t otal of 20 F(1)s from interspecific crosses among five different taxa in th e section Bifolium was examined. Twelve F(1)s were from six crosses between L. cuneifolia (4x) and L. divaricata (2x) (Peru or Argentina) or L trident ata (2x or 4x). Eight F(1)s were from two sets of reciprocal crosses betwee n L. divaricata (2x) (Argentina) and L tridentata (2x). Length polymorphism was observed in all three regions of cpDNA that separated L. cuneifolia pa rents from L divaricata and L. tridentata parents and in one of the three c pDNA regions that differentiated L. divaricata (Argentina) parents from L. tridentata (2x) parents. In each case, it was the paternal cpDNA marker tha t appeared in the F-1 individuals. This was further confirmed by restrictio n fragment length polymorphism (RFLP) analysis of the amplified cpDNA fragm ents. Larrea may be the fifth genus reported in angiosperms with a paternal bias in cpDNA transmission possible mechanisms that may result in paternal cpDNA inheritance were briefly reviewed. Based on the observed uniparental paternal inheritance of cpDNA, restriction analysis of the three cpDNA reg ions and previous cytogenetic studies, L. divaricata was probably the mater nal progenitor of L, cuneifolia.