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Alfin-like proteins (ALs) form a plant-specific transcription factor (TF) gene family involved in the regulation of plant growth and development, and abiotic stress response. In this study, 30 ALs were identified in Brassica napus ecotype 'Zhongshuang 11' genome (BnaALs), and unevenly distributed on 15 chromosomes. Structural characteristic analysis showed that all of the BnaALs contained two highly conserved domains: the N terminal DUF3594 domain and the C-terminal PHD-finger domain. The BnaALs were classified into four groups (Group I-IV), supported by conserved intron–exon and protein motif structures in each group. The allopolyploid event between B. oleracea and B. rapa ancestors and the small-scale duplication events in B. napus both contributed to the large BnaALs expansion. The promoter regions of BnaALs contained multiple abiotic stress cis-elements. The BnaALs in I-IV groups were mainly expressed in cotyledon, petal, root, silique, and seed tissues, and the duplicated gene pairs shared highly similar expression patterns. RNA-seq and RT-qPCR analysis showed that BnaALs were obviously induced by low nitrogen (LN) and low phosphorus (LP) treatments in roots. Overexpressing BnaAL02 and BnaAL28 in Arabidopsis demonstrated their functions in response to LN and LP stresses. BnaAL28 enhanced primary roots' (PRs) length and lateral roots' (LRs) number under LP and LN conditions, where BnaAL02 can inhibit LR numbers under the two conditions. They can promote root hair (RH) elongation under LP conditions; however, they suppressed RH elongation under LN conditions. Our result provides new insight into the functional dissection of this family in response to nutrient stresses in plants. [ABSTRACT FROM AUTHOR]

In crops there are quantitative trait loci (QTLs) in which some of the causal quantitative trait genes (QTGs) have not been functionally characterized even in the model plant Arabidopsis. We propose an approach to delineate QTGs in rapeseed by coordinating expression of genes located within QTLs and known orthologs related to traits from Arabidopsis. Using this method in developing siliques 15 d after pollination in 71 lines of rapeseed, we established an acyl-lipid metabolism co-expression network with 21 modules composed of 270 known acyl-lipid genes and 3503 new genes. The core module harbored 76 known genes involved in fatty acid and triacylglycerol biosynthesis and 671 new genes involved in sucrose transport, carbon metabolism, amino acid metabolism, seed storage protein processes, seed maturation, and phytohormone metabolism. Moreover, the core module closely associated with the modules of photosynthesis and carbon metabolism. From the co-expression network, we selected 12 hub genes to identify their putative Arabidopsis orthologs. These putative orthologs were functionally analysed using Arabidopsis knockout and overexpression lines. Four knockout mutants exhibited lower seed oil content, while the seed oil content in 10 overexpression lines was significantly increased. Therefore, combining gene co-expression network analysis and QTL mapping, this study provides new insights into the detection of QTGs and into acyl-lipid metabolism in rapeseed. [ABSTRACT FROM AUTHOR]

Seed weight (SW) is one of three determinants of seed yield, which positively correlates with silique length (SL) in Brassica napus (rapeseed). However, the genetic mechanism underlying the relationship between seed weight (SW) and silique length (SL) is largely unknown at present. A natural population comprising 157 inbred lines in rapeseed was genotyped by whole-genome re-sequencing and investigated for SW and SL over four years. The genome-wide association study identified 20 SNPs in significant association with SW on A01, A04, A09, C02, and C06 chromosomes and the phenotypic variation explained by a single locus ranged from 11.85% to 34.58% with an average of 25.43%. Meanwhile, 742 SNPs significantly associated with SL on A02, A03, A04, A07, A08, A09, C01, C03, C04, C06, C07, and C08 chromosomes were also detected and the phenotypic variation explained by a single locus ranged from 4.01 to 48.02% with an average of 33.33%, out of which, more than half of the loci had not been reported in the previous studies. There were 320 overlapping or linked SNPs for both SW and SL on A04, A09, and C06 chromosomes. It indicated that both overlapping and independent genetic loci controlled both SW and SL in B. napus. On the haplotype block on A09 chromosome, the allele variants of a known gene BnaA.ARF18.a controlling both SW and SL were identified in the natural population by developing derived cleaved amplified polymorphic sequence (dCAPS) markers. These findings are valuable for understanding the genetic mechanism of SW and SL and also for rapeseed molecular breeding programs. [ABSTRACT FROM AUTHOR]