Genetic analysis of main flower characteristics in the F1 generation derived from intraspecific hybridization between Plumbago auriculata and Plumbago auriculata f. alba

Abstract

The ornamental characteristics of Plumbago auriculata are mainly reflected in the floral organ. Exploring the genetic inheritance of flower characteristics is important for breeding new varieties. In this study, F1 segregating populations were obtained by using artificial hybridization (direct cross and reciprocal cross) between P. auriculata and its variant P. auriculata f. alba. A heterosis analysis and mixed major gene plus polygene inheritance model were used to investigate the inheritance of eight flower characteristics in the F1 generation: inflorescence length (IL), inflorescence diameter (ID), number of flowers per inflorescence (NFI), beginning of the blooming period (BBP), inflorescence number (IN), flower diameter (FD), flower length (FL) and corolla color value (CCV). In addition to the CCV, the other flower characteristics showed continuous unimodal and skewed distributions, which indicated that these characteristics were quantitative and controlled by polygenes. Although transgressive heterosis was observed only for BBP in both combinations, transgressive segregation was commonly observed, except for CCV in the F1 generation; these findings could facilitate the selection of beneficial individuals for breeding. Genetic analysis revealed that NFI could be described by a B-3 genetic model via two pairs of additive major genes; BBP could be followed by a B-2 genetic model via two pairs of additive-dominance major genes; both FL and FD could be described by a B-6 genetic model via two pairs of major genes that were equally dominant; IN was best fit by the A-1 model, which was controlled by a pair of additive-dominant-epistatic major genes; and IL and ID were best fit by the A-0 model, indicating that both characteristics were controlled by only polygenes. The heritability of the major genes controlling the NFI, BBP, FD, FL and IN traits were 92.58 %, 94.40 %, 63.42 %, 54.23 % and 65.67 %, respectively, indicating that these five characteristics were less affected by the environment. These results can provide some reference for quantitative trait locus (QTL) mapping and molecular marker-assisted breeding of the main flower characteristics in P. auriculata.