Genetic characterisation of a novel male sterile two-type line system 19F08AB in Brassica napus L

Rapeseed (Brassica napus L.) is a major global oilseed crop and exhibits significant heterosis. The discovery and characterisation of novel male-sterile accessions remain fundamental for harnessing heterosis in rapeseed breeding. Previously, we developed a male sterile two-type line system 19F08AB in B. napus. In this study, anther abortion in 19F08A was characterised using the squash method. The inheritance of male sterility in 19F08A and its genetic relationship to reported male sterile accessions in rapeseed was investigated using classical genetic analysis and male-sterility-gene-specific molecular markers. Results indicated that male sterile flowers of 19F08A exhibit flat petals, reduced floral organs, short filaments, and completely degenerated stamens devoid of pollen. Pollen mother cells in 19F08A degenerated at the pre-meiotic stage and aborted completely at the tetrad stage, with no dyad or tetrad formation observed. This suggested that 19F08A represents a meiosis abnormality-type male sterility. Classical genetic and molecular marker analysis revealed that male-sterile plants 19F08A carry the genotype of pol (RfpRfpMsms), whereas fertile plants 19F08B possess pol (RfpRfpmsms). The effect of the pol cytoplasm was masked by the Rfp gene. Therefore, fertility in 19F08AB is controlled by a pair of nuclear genes (Ms/ms), with male sterility exhibiting dominance over fertility. The application prospects of this male-sterile accession are also discussed. These findings expand the pool of male-sterile resources available for B. napus hybrid breeding and contribute to plant male sterility theory.