Phenotypic segregation and selection of transgressive ideotypes in Adenium obesum

Abstract Corolla pigmentation and petal arrangement are the main breeding targets in Adenium obesum , and the efficiency of a breeding programme depends on knowing how these phenotypes are transmitted to the progeny and how much variation each cross makes available for selection. In this study, we described the phenotypic segregation of these traits in genetically defined full-sib families of A. obesum and identified transgressive individuals and ideotypes in the progeny. Reciprocal crosses among three contrasting parents generated four F 1 families comprising 351 plants, and controlled pollinations among full-sib F 1 plants generated an F 2 population of 91 plants derived from seven F 1 × F 1 combinations involving eleven identified F 1 parents. The presence of anthocyanin behaved as a dominant character in all crosses, and every F 1 plant produced a pigmented corolla; non-pigmented, white-flowered plants were recovered only in the F 2 generation. Petal arrangement segregated homogeneously in the four F 1 families. Positive transgressive individuals occurred in every family and for every morpho-ornamental trait. The RB and BR reciprocal crosses are recommended as the primary source populations for improving flower longevity, given the exceptionally high frequency of positive transgressive individuals (> 89%). Fifteen F 1 genotypes and sixteen F 2 genotypes met the ideotypes defined for the programme, covering red, magenta, purple and white corollas with compound arrangement and contrasting variegation patterns, and constitute the working collection for the next breeding cycle.