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

Rapeseed (<i>Brassica napus</i> L.) isamajor global oilseed crop and exhibits significant heterosis. The discovery and characterisation ofnovel male-sterile accessions remain fundamental for harnessing heterosis inrapeseed breeding. Previously, wedeveloped amale sterile two-type line system 19F08AB in<i>B. napus</i>. Inthis study, anther abortion in19F08A was characterised using the squash method. The inheritance ofmale sterility in19F08A and its genetic relationship toreported male sterile accessions inrapeseed was investigated using classical genetic analysis and male-sterility-gene-specific molecular markers. Results indicated that male sterile flowers of19F08A exhibit flat petals, reduced floral organs, short filaments, and completely degenerated stamens devoid ofpollen. Pollen mother cells in19F08A degenerated atthe pre-meiotic stage and aborted completely atthe tetrad stage, with nodyad ortetrad formation observed. This suggested that 19F08A represents ameiosis abnormality-type male sterility. Classical genetic and molecular marker analysis revealed that male-sterile plants 19F08A carry the genotype of<i>pol</i> (<i>RfpRfpMsms</i>), whereas fertile plants 19F08B possess <i>pol</i> (<i>RfpRfpmsms</i>). The effect ofthe <i>pol</i> cytoplasm was masked bythe <i>Rfp</i> gene. Therefore, fertility in19F08AB iscontrolled byapair ofnuclear genes (<i>Ms</i>/<i>ms</i>), with male sterility exhibiting dominance over fertility. The application prospects ofthis male-sterile accession are also discussed. These findings expand the pool ofmale-sterile resources available for <i>B. napus</i> hybrid breeding and contribute to plant male sterility theory.