Brassica napus is an important cash crop broadly grown for the vegetable and oil values. Yellow-seeded B. napus is preferred by breeders due to its improved oil and protein quality, less pigments and lignin compared with the black-seeded counterpart. This study compared the differences in flavonoid and fatty acid contents between yellow rapeseed from the progenies of B. napus–Sinapis alba somatic hybrids and the black-seeded counterpart using RNA-seq analysis. Through HPLC-PDA-ESI(−)/MS2 analysis, it was found that phenylpropanoids and flavonoids (i.e., isorhamnetin, epicatechin, kaempferol, and other derivatives) in yellow seed were significantly lower than those in black seed. The fatty acid (FA) content in yellow rapeseed was higher than that in black rapeseed due to the variation of C16:0, C18:0, C18:1, C18:2, and C18:3 contents. RNA-seq analysis of seeds at four and five weeks after flowering (WAF) indicated that differentially expressed genes (DEGs) between black and yellow rapeseeds were enriched in flavonoid and FA biosynthesis, including BnTT3, BnTT4, BnTT18, and BnFAD2. Also, genes related to FA biosynthesis, desaturation and elongation (FAD3, LEC1, FUS3, and LPAT2) in yellow seed were up-regulated compared to those in black seed, while genes involved in beta-oxidation cycle (AIM1 and KAT2) of yellow seed were down-regulated compared to those in black seed. The DEGs related to the variation of flavonoids, phenylpropanoids, and FAs would help improve the knowledge of yellow seed character in B. napus and promote rapeseed improvement.
Phenotypic screening of soybean germplasm suitable for high planting density is currently the most viable strategy to increase yield. Previous studies have shown that soybean varieties with dwarf features and a short petiole often exhibit a compact plant architecture which could improve yield through increased planting density, although previously reported short petiole accessions were ultimately not usable for breeding in practice. Here, we established a method to assess petiole length and identified an elite mutant line, M657, that exhibits high photosynthetic efficiency. The agronomic traits of M657 were evaluated under field conditions, and appeared to be stable for short petiole across seven locations in northern, Huang–Huai, and southern China from 2017 to 2018. Compared with the Jihuang 13 wild type, the mutant M657 was shorter in both petiole length and plant height, exhibited lower total area of leaf, seed weight per plant and 100-seed weight, but had an increased number of effective branches and the growth period was prolonged by 2–7 days. Using M657 as a parental line for crosses with four other elite lines, we obtained four lines with desirable plant architecture and yield traits, thus demonstrating the feasibility of adopting M657 in breeding programs for soybean cultivars of high density and high yield.
Insufficient available phosphorus in soil has become an important limiting factor for the improvement of yield and quality in soybean. The mining of QTLs and candidate genes controlling soybean phosphorus utilization related traits is a necessary strategy to solve this problem. In this study, 11 phosphorus utilization related traits of a natural population of 281 typical soybean germplasms and a recombinant inbred line (RIL) population of 270 lines were evaluated under different phosphorus conditions at two critical stages: the four-leaf stage as the seedling critical stage was designated as the T1 stage, and the six-leaf stage as the flowering critical stage was designated as the T2 stage. In total, 200 single nucleotide polymorphism (SNP) loci associated with phosphorus utilization related traits were identified in the natural population, including 91 detected at the T1 stage, and 109 detected at the T2 stage. Among these SNP loci, one SNP cluster (s715611375, ss715611377, ss715611379 and ss715611380) on Gm12 was shown to be significantly associated with plant height under the low phosphorus condition at the T1 stage, and the elite haplotype showed significantly greater plant height than the others. Meanwhile, one pleiotropic SNP cluster (ss715606501, ss715606506 and ss715606543) on Gm10 was found to be significantly associated with the ratio of root/shoot, root and total dry weights under the low phosphorus condition at the T2 stage, and the elite haplotype also presented significantly higher values for related characteristics under the phosphorus starvation condition. Furthermore, four co-associated SNP loci (ss715597964, ss715607012, ss715622173 and ss715602331) were identified under the low phosphorus condition at both the T1 and T2 stages, and 12 QTLs were found to be consistent with these genetic loci in the RIL population. More importantly, 14 candidate genes, including MYB transcription factor, purple acid phosphatase, sugar transporter and HSP20-like chaperones superfamily genes, etc., showed differential expression levels after low phosphorus treatment, and three of them were further verified by qRT-PCR. Thus, these genetic loci and candidate genes could be applied in marker-assisted selection or map-based gene cloning for the genetic improvement of soybean phosphorus utilization.
Salinity threatens soybean germination, growth and production. The germination stage is a key period in the life of soybean. Wild soybean contains many genes related to stress resistance that are valuable resources for the genetic improvement of soybean. To identify the genetic loci of wild soybean that are active during seed germination under salt stress, two populations, a soybean interspecific hybrid population comprising 142 lines and a natural population comprising 121 wild soybean accessions, were screened for three germination-related traits in this study. By using single-nucleotide polymorphism (SNP) markers with three salt tolerance indices, 25 quantitative trait loci (QTLs), 21 significant SNPs (–log10(P)≥4.0) and 24 potential SNPs (3.5<–log10(P)<4.0) were detected by linkage mapping and a genome-wide association study (GWAS) in two environments. The key genetic region was identified based on these SNPs and QTLs. According to the gene functional annotations of the W05 genome and salt-induced gene expression qRT-PCR analysis, GsAKR1 was selected as a candidate gene that responded to salt stress at the germination stage in the wild soybean. These results could contribute to determining the genetic networks of salt tolerance in wild soybean and will be helpful for molecular marker-assisted selection in the breeding of salt-tolerant soybean.
Pod shattering is an important domesticated trait which can cause great economic loss of crop yield in cultivated soybean. In this study, we utilized two recombinant inbred line populations (RILs, CY, Huachun 2×Wayao; GB, Guizao 1×B13) to identify quantitative trait loci (QTLs) associated with pod shattering in soybean across multiple environments. A total of 14 QTLs for pod shattering were identified in the two RIL populations, which had LOD scores ranging from 2.64 to 44.33 with phenotypic variance explanation (PVE) ranging from 1.33 to 50.85%. One QTL qPS16-1, located on chromosome 16, included a well-known functional gene Pod dehiscence 1 (Pdh1) that was reported previously. Ten new putative QTLs were validated in two RIL populations, and their LOD scores were between 2.55 and 4.24, explaining 1.33 to 2.60% of the phenotypic variation. Of which four novel QTLs (qPS01-1, qPS03-2, qPS05-1, and qPS07-1) could be detected in two environments where nine genes had specific changes in gene expression. Although the nine genes may have significant effects on pod shattering of soybean, their detailed functions still need to be further explored in the future. The results of this study will facilitate a better understanding of the genetic basis of the pod shattering-resistant trait and benefit soybean molecular breeding for improving pod shattering resistance
The leaf is the main photosynthetic organ of plants, and it plays a significant role in the yield of crop species. Identifying the causal mutations and candidate genes that underlie leaf phenotypic variation is an important breeding target in soybean grain yield improvement. An ethyl methyl sulfonate (EMS)-induced soybean mutant DWARFCRINKLEDLEAF1 (DCL1) with an aberrant crinkled leaf phenotype was identified in the background of the soybean cultivar Zhongpin 661 (Zp661). We constructed an F2 segregating population from a cross between Zp661 and DCL1 in order to investigate the genomic locus associated with the crinkled leaf trait. Using bulk segregant analysis (BSA) combined with the whole-genome resequencing method, the Euclidean distance (ED) correlation algorithm detected 12 candidate genomic regions with a total length of 20.32 Mb that were linked to the target trait. Following a comparative analysis of the sequence data for the wild-type and mutant pools, only one single nucleotide mutation (C:G>T:A) located on the first exon of Glyma.19G207100 was found to be associated with the trait. Candidate gene validation based on a CAPS marker derived from the detected single-nucleotide polymorphism (SNP) indicated a nucleotide polymorphism between the two parents. Therefore, our findings reveal that Glyma.19G207100, which is renamed as GLYCINE MAX DWARF CRINKLED LEAF 1 (GmDCL1), is a promising candidate gene involved in the morphogenesis of the crinkled leaf trait of the soybean mutant DCL1. This study provides a basis for the functional validation of this gene, with prospects for soybean breeding targeting grain yield enhancement.
Soybean yield has been increased through high planting density, but investigating plant height and petiole traits to select for compact architecture, lodging resistance, and high yield varieties is an underexplored avenue to improve yield. We compared the relationship between yield-related traits, lodging resistance, and petiole-associated phenotypes in the short petiole germplasm M657 with three control accessions over 2017-2018 in four locations of the Huang-Huai region. The results showed M657 exhibited stable and high tolerance to high planting density and resistance to lodging, especially at the highest density (8×105 plants ha-1). Regression analysis showed that shorter petiole length was significantly associated with increased lodging resistance. Yield analysis showed that M657 achieved higher yields under higher densities, especially in the north Huang-Huai region. There are markedly different responses to intra- and inter-row spacing designs among varieties in both lodging and yield related to location and density. Lodging was positively correlated with planting density, plant height, petiole length, and number of effective branches, and negatively correlated with stem diameter, seed number per plant, and seed weight per plant. The yield of soybean was increased by appropriately increasing planting density on the basis of current soybean varieties in the Huang-Huai region. This study provides a valuable new germplasm resource for introgression of compact architecture traits amenable to high yield in high density planting systems and establishes a high-yield model of soybean in the Huang-Huai region.
Cereal and legume intercropping has been widely adopted to increase crop productivity in sustainable farming systems worldwide. Among different intercropping combinations, millet and peanut intercropping can be adapted to most water-limited areas. However, there are few studies on the differences in yield characteristics and nitrogen use efficiency between millet/peanut intercropping and monocultures under different nitrogen (N) application rates. The objective of this study was to determine the yield advantages and economic benefits, as well as the appropriate N application rate, of millet/peanut intercropping. A two-year field experiment was conducted with three cropping patterns (monoculture millet, monoculture peanut and millet/peanut intercropping) and four N rates (0, 75, 150 and 225 kg ha−1). The results showed that the land equivalent ratio (LER) and net effect (NE) of the intercropping system reached their highest levels at the N input of 150 kg ha−1 in 2018 and 2019 (1.04 for LER, 0.347 Mg ha−1 for NE, averaged across two years). Millet was the dominant crop in the intercropping system (aggressivity of millet and peanut (Amp)>0, competitive ratio of millet and peanut (CRmp)>1), and millet yields achieved their highest values at N inputs of 225 kg ha−1 for monoculture and 150 kg ha−1 for intercropping. NUE reached its highest levels with N inputs of 150 kg ha−1 for all planting patterns over the two years. Intercropping combined with an N input of 150 kg ha−1 achieved the highest net income of 2 791 USD ha−1, with a benefit-cost ratio of 1.56, averaged over the two years. From the perspective of economics and agricultural sustainable development, millet/peanut intercropping at 150 kg N ha−1 seems to be a promising alternative to millet or peanut monoculture.
Copyright © Journal of Integrative Agriculture
Sponsored by Chinese Academy of Agricultural Sciences (CAAS)
Co-sponsored by China Association of Agricultural Science Societies (CAASS)
Publishing Service by Elsevier B.V.
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