Evolutionary Relationships between the Diploid Turners grandiflora and the Octoploid T. fernandezii (Turneraceae)

Abstract

Aiming to analyze the evolutionary relationships between the diploid species Turnera grandiflora (2n = 2x = 10) and the octoploid T. fernandezii (2n = 8x = 40), inter-specific hybrids were recovered by in vitro embryo rescue methods. The full-grown plants obtained were all pentaploids (2n = 5x = 25) confirming their hybrid nature. The chromosome associations observed in the hybrids during meiosis were indicative for an autopentaploid, suggesting that T. fernandezii carries the genome of T. grandiflora (CgCg) but at the octoploid level (CgCg CgCg CgCg CgCg). This fact confirms a close evolutionary relationship between the species and supports the hypothesis that T. grandiflora is the progenitor of T. fernandezii. A tentative hypothesis regarding the autopolyploid origin of T. fernandezii is finally formulated