Expression analysis of MADS-box genes in phenotypically distinct carrot cytoplasmic male sterile lines and their maintainers

Abstract

The utilization of maternally inherited loss of male fertility has facilitated the development of hybrid seeds for commercial production of carrots. The loss of male sterility is due to alterations in floral organs that render the male reproductive organs unfunctional or may cause the complete elimination of a specific floral organ. Although organ alterations have previously been studied in carrot cytoplasmic male sterile lines to characterize them on phenotypic and molecular basis, the role of MADS-box genes in the development of different floral organs has not been emphasized. In this study, the analogous use of stereo microscopy and qRT-PCR enabled the characterization of the role MADS-box genes play during carrot floral organ development. A total of 25 CMS lines were screened to determine the floral organ alterations. Out of which, four phenotypically distinct floral morphotypes were identified in the CMS germplasm, i.e., sepaloid type, brown anther type, miniature leaf type and lance type. Further, these four phenotypically distinct CMS lines were subjected to quantitative expression analysis of eight floral identity MADS-Box genes. The gene expression results confirmed that variation in the expression of floral identity genes is responsible for organ alteration in male sterile flowers of carrot.