Herança genética e seleção em progênies de Rosa-do-deserto

Abstract

The ornamental plant market thrives on novelty and, to meet demand, breeders seek new cultivars with floral attributes of color and shape that increase ornamental value. Adenium obesum, popularly known as desert rose, is a prominent plant in the recent floricultural scene. Understanding the genetic mechanism of development of morphological characters can contribute to screening parents and selection of descendants in future breeding programs. In order to understand the genetic bases for the development of new cultivars, the objective of this study was to conduct studies of genetic inheritance of color and petal arrangement in full-sib families in desert rose and select superior genotypes. Controlled manual pollination was performed between three parents with distinct floral attributes that constituted the segregating populations used for inheritance studies and evaluation of morpho ornamental characteristics. The experimental progenies (F1 and F2) constituted the families of A. obesum, namely: RB (purple and simple corolla ♀ X white and compound corolla ♂), BR (white and compound corolla ♀ X purple and simple corolla ♂), BRo (white and compound corolla ♀ X pink and simple corolla ♂) and RoB (pink and simple corolla ♀ X white and compound corolla ♂). The chi-square test (χ²) was applied to analyze the segregation of color and petal arrangement traits. The frequency distribution of the F1 progenies in phenotypic classes of morpho ornamental traits was evaluated. The presence of anthocyanins was dominant in all crosses and double dominant epistasis was associated with the inheritance of this trait. The results indicated a digenic nature and epistatic interactions in the control of color and petal arrangement. The hypotheses of dominant (RB, BRo and RoB) and dominant by recessive (BR) epistasis were not rejected and appear to explain the reason for phenotypic segregation in these progenies. The hypotheses of dominant by recessive epistasis (RB F2) and double recessive epistasis (BR, BRo and RoB) explained the petal arrangement phenotypes in the progenies of the present study. The difference between the types of epistasis in each progeny was attributed to the magnitude of the genetic effects and the genotypic composition of the parents. Through the analysis of distribution, as well as genetic dissimilarity, it was possible to identify and designate candidate genotypes to continue the breeding program.