Development of gene-based markers from functional Arabidopsis thaliana genes involved in phosphorus homeostasis and mapping in Brassica napus

Brassica napus is an important oilseed and fodder crop grown throughout the world. Although it is widely grown, little is known about the molecular basis of phosphorus (P) homeostasis for this species. In this research, a population of 124 recombinant inbred lines (RILs) (designated as BE-RIL) derived from a cross between P-inefficient cv. 'B104-2' and P-efficient cv. 'Eyou Changjia' was used to construct a genetic map of P homeostasis genes. A set of gene-based markers (GBMs) was developed from functional genes involved in Arabidopsis thaliana P homeostasis. In total, 46 GBMs corresponding to 26 genes, assigned to eight functional categories, were integrated into the BE-RIL map. A total of 243 simple sequence repeat (SSR) markers were developed from 171 bacterial artificial chromosome (BAC) end sequences and/or B. rapa seed BAC sequences. Of these SSR markers, 74 were added to the BE-RIL map. Based on the newly constructed genetic map, comparative genetic analysis between A. thaliana and B. napus was performed. A total of 90 conserved genomic blocks were aligned between A. thaliana pseudochromosomes and the BE-RIL linkage groups. According to physical positions on the Arabidopsis genome, 1223 orthologs of 356 genes involved in Arabidopsis P homeostasis were mapped onto syntenic blocks and insertion segments. This high-density genetic map will be useful for identifying quantitative trait loci (QTL) that control P homeostasis and putative candidate genes for the efficient use of P in B. napus.