Spontaneous male sterility is an advantageous trait for both producing hybrids and understanding the developmental process of the male reproductive unit in many crops. Lu et al. use a map-based cloning strategy together with comparative mapping to study the triallelic genetic male-sterile locus BnMs5 in Brassica napus, and delimit it to a 21-kb fragment of the A8 chromosome. Sequence analysis suggests that BnMs5 originates from the B. rapa MF2 subgenome, and may reside in a hotspot region of chromosomal evolution. This work paves the way for further cloning of BnMs5, and presents a powerful method for mapping loci in plants with complex genomic architecture.
Low levels of phosphorous in soils seriously limit seed production of Brassica napus. Ding et al. investigate phenotypic variation of seed yield and yield-related traits in B. napus plants grown with contrasting supplies of P, and identify a total of 74 putative quantitative trait loci (QTLs). The results suggest that different genetic determinants are involved in controlling yield and yield-related traits under normal and low P conditions, and the QTLs detected under reduced P supply may prove useful in marker-assisted selection.