Background: TIFY is a plant-specific protein family with a diversity of functions in plant development and responses to stress and hormones, which contains JASMONATE ZIM-domain (JAZ), TIFY, PPD and ZML subfamilies. Despite extensive studies of TIFY family in many other species, TIFY has not yet been characterized in Brassica napus. Results: In this study, we identified 77, 36 and 39 TIFY family genes in the genome of B. napus, B. rapa and B. oleracea, respectively. Results of the phylogenetic analysis indicated the 170 TIFY proteins from Arabidopsis, B. napus, B. rapa and B. oleracea could be divided into 11 groups: seven JAZ groups, one PPD group, one TIFY group, and two ZIM/ZML groups. The molecular evolutionary analysis showed that TIFY genes were conserved in Brassicaceae species. Gene expression profiling and qRT-PCR revealed that different groups of BnaTIFY members have distinct spatiotemporal expression patterns in normal conditions or following treatment with different abiotic/biotic stresses and hormones. The BnaJAZ subfamily genes were predominantly expressed in roots and up-regulated by NaCl, PEG, freezing, methyl jasmonate (MeJA), salicylic acid (SA) and Sclerotinia sclerotiorum in leaves, suggesting that they have a vital role in hormone signaling to regulate multiple stress tolerance in B. napus. Conclusions: The extensive annotation and expression analysis of the BnaTIFY genes contributes to our understanding of the functions of these genes in multiple stress responses and phytohormone crosstalk in B. napus.

Annexins (ANN) are a multigene, evolutionarily conserved family of calcium-dependent and phospholipid-binding proteins that play important roles in plant development and stress resistance. However, a systematic comprehensive analysis of ANN genes of Brassicaceae species (Brassica rapa, Brassica oleracea, and Brassica napus) has not yet been reported. In this study, we identified 13, 12, and 26 ANN genes in B. rapa, B. oleracea, and B. napus, respectively. About half of these genes were clustered on various chromosomes. Molecular evolutionary analysis showed that the ANN genes were highly conserved in Brassicaceae species. Transcriptome analysis showed that different group ANN members exhibited varied expression patterns in different tissues and under different (abiotic stress and hormones) treatments. Meanwhile, same group members from Arabidopsis thaliana, B. rapa, B. oleracea, and B. napus demonstrated conserved expression patterns in different tissues. The weighted gene coexpression network analysis (WGCNA) showed that BnaANN genes were induced by methyl jasmonate (MeJA) treatment and played important roles in jasmonate (JA) signaling and multiple stress response in B. napus.

Strong artificial and natural selection causes the formation of highly conserved haplotypes that harbor agronomically important genes. GWAS combination with haplotype analysis has evolved as an effective method to dissect the genetic architecture of complex traits in crop species. We used the 60 K Brassica Infinium SNP array to perform a genome-wide analysis of haplotype blocks associated with oleic acid (C18:1) in rapeseed. Six haplotype regions were identified as significantly associated with oleic acid (C18:1) that mapped to chromosomes A02, A07, A08, C01, C02, and C03. Additionally, whole-genome sequencing of 50 rapeseed accessions revealed three genes (BnmtACP2-A02, BnABCI13-A02 and BnECI1-A02) in the A02 chromosome haplotype region and two genes (BnFAD8-C02 and BnSDP1-C02) in the C02 chromosome haplotype region that were closely linked to oleic acid content phenotypic variation. Moreover, the co-expression network analysis uncovered candidate genes from these two different haplotype regions with potential regulatory interrelationships with oleic acid content accumulation. Our results suggest that several candidate genes are closely linked, which provides us with an opportunity to develop functional haplotype markers for the improvement of the oleic acid content in rapeseed.