A recessive epistatic genic male sterility (REGMS) two-type line, 9012AB, has been used for rapeseed hybrid seed production in China. The male sterility of 9012AB is controlled by two recessive duplicate sterile genes (ms1 and ms2) interacting with one recessive epistatic suppressor gene (esp). Homozygosity at the esp locus (espesp) suppresses the expression of the recessive male sterility trait in homozygous ms1ms1ms2 ms2 plants. In this study, we used a combination of bulked segregant analyses and amplified fragment length polymorphism (AFLP) to identify markers linked to the suppressor gene in a BC 1 population. From the survey of 1024 AFLP primer combinations, eight markers tightly linked to the target gene were identified. The two closest markers flanking both sides of Esp, P9M5 370 and S16M14 780 , had a genetic distance of 1.4 cM and 2.1 cM, respectively. The AFLP fragment from P4M8 190 , which co-segregated with the target gene was converted into a sequence characterized amplified region marker. The availability of linked molecular markers will facilitate the utilization of REGMS in hybrid breeding in Brassica napus.

Breeding low phytic acid (lpa) crops is a strategy that has potential to both improve the nutritional quality of food and feed and contribute to the sustainability of agriculture. Here, we review the lipid-independent and -dependent pathways of phytate synthesis and their regulatory mechanisms in plants. We compare the genetic variation of the phytate concentration and distribution in seeds between dicot and monocot species as well as the associated temporal and spatial expression patterns of the genes involved in phytate synthesis and transport. Quantitative trait loci or significant single nucleotide polymorphisms for the seed phytate concentration have been identified in different plant species by linkage and association mapping, and some genes have been cloned from lpa mutants. We summarize the effects of various lpa mutations on important agronomic traits in crop plants and propose SULTR3;3 and SULTR3;4 as optimal target genes for lpa crop breeding.

Background and Aims Brassica napus is one of the most important oilseed crops worldwide. Seed yield of B. napus significantly correlates with the primary root length (PRL). The aims of this study were to identify quantitative trait loci (QTLs) for PRL in B. napus. Methods QTL-seq and conventional QTL mapping were jointly used to detect QTLs associated with PRL in a B. napus double haploid (DH) population derived from a cross between cultivar Tapidor and Ningyou 7. The identified major locus was confirmed and resolved by an association panel of B. napus and an advanced backcross population. RNA-seq analysis of two long-PRL lines (Tapidor and TN20) and two short-PRL lines (Ningyou 7 and TN77) was performed to identify differentially expressed genes in primary root underlying the target QTLs. Key Results A total of 20 QTLs impacting PRL in B. napus grown at a low phosphorus (P) supply were found by QTL-seq. Eight out of ten QTLs affecting PRL at a low P supply discovered by conventional QTL mapping could be detected by QTL-seq. The locus qPRL-C06 identified by QTL-seq was repeatedly detected at both an optimal P supply and a low P supply by conventional QTL mapping. This major constitutive QTL was further confirmed by regional association mapping. qPRL-C06 was delimited to a 0.77-Mb genomic region on chromosome C06 using an advanced backcross population. A total of 36 candidate genes within qPRL-C06 were identified that showed variations in coding sequences and/or exhibited significant differences in mRNA abundances in primary root between the long-PRL and short-PRL lines, including five genes involved in phytohormone biosynthesis and signaling. Conclusions These results both demonstrate the power of the QTL-seq in rapid QTL detection for root traits and will contribute to marker-assisted selective breeding of B. napus cultivars with increased PRL.