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Oil and protein content and fatty acid composition are quality traits in peanut. Elucidating the genetic mechanisms underlying these traits may help researchers to obtain improved cultivars by molecular breeding. Whole-genome resequencing of a recombinant inbred population of 318 lines was performed to construct a high-density linkage map and identify QTL for peanut quality. The map, containing 4561 bin markers, covered 2032 cM with a mean marker density of 0.45 cM. A total of 110 QTL for oil and protein content, and fatty acid composition were mapped on the 18 peanut chromosomes. The QTL qA05.1 was detected in four environments and showed a major phenotypic effect on the contents of oil, protein, and six fatty acids. The genomic region spanned by qA05.1, corresponding to a physical interval of approximately 1.5 Mb, contains two SNPs polymorphic between the parents that could cause missense mutations. The two SNP sites were employed as KASP markers and validated using lines with extremely high and low oil contents. These sites may be useful in the marker-assisted breeding of peanut cultivars with high oil contents.

Peanut shell plays key roles in protecting the seed from diseases and pest infestation but also in the processing of peanut and is an important byproduct of peanut production. Most studies on peanut shell have focused on the utilization of its chemical applications, but the genetic basis of shell-related traits is largely unknown. A panel of 320 peanut (Arachis hypogaea) accessions including var. hypogaea, var. vulgaris, var. fastigiata and var. hirsuta was used to study the genetic basis of two physical and five microstructure-related traits in peanut shell. Significant phenotypic differences were revealed among the accessions of var. hypogaea, var. hirsuta, var. vulgaris and var. fastigiata for mechanical strength, thickness, three sclerenchymatous layer projections and main cell shape of the sclerenchymatous layer. We identified 10 significant single nucleotide polymorphisms (SNPs) through genome-wide association study (P < 5.0 × 10−6) combining the shell-related traits and high-quality SNPs. In total, 192 genes were located in physical proximity to the significantly associated SNPs, and 11 candidate genes were predicted related to their potential contribution to the development and structure of the peanut shell. All SNPs were detected on the B genome demonstrating the biased contribution of the B genome for the phenotypical make-up of peanut. Exploring the newly identified candidate genes will provide insight into the molecular pathways that regulate peanut shell-related traits and provide valuable information for molecular marker-assisted breeding of an improved peanut shell.

Peanut (Arachis hypogaea L.) is one of the important oil crops worldwide. Revealing the molecular basis of seed oil synthesis and analyzing key candidate genes may have important implications for enhancing peanut production. In this study, we investigated the dynamic changes in the oil accumulation rate and gene expression levels in developing peanut seeds. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the up-regulated differentially expressed genes (DEGs) among three varieties at 25–35 days after flowering (DAF) were involved in fatty acid synthesis, carbon metabolism, and pyruvate metabolism. Between 25 and 35 DAF, the up-regulated DEGs in the high-oil varieties, but not in the low-oil variety, were related to acetyl-CoA synthesis. We examined the differences in the varieties at the same stages. We analyzed the lipid metabolism-related genes by protein–protein interaction (PPI), and finally identified 57 DEGs that may influence the peanut oil content. These candidate genes included three genes encoding acetyl-CoA carboxylase (ACCase), one gene encoding ketoacyl-ACP synthase III (KASIII), one gene encoding hydroxyacyl-ACP dehydrase (HAD), and one gene encoding enoyl-ACP reductase (EAR), which form the Type II fatty acid synthase complex. Additionally, we also found that 11 transcription factors may affect oil content. These identified candidate genes may help to further clarify the molecular basis of the oil accumulation in peanut seeds.

Background: Oil and protein content, as well as fatty acid composition, are important quality traits in peanut. Elucidating the genetic mechanisms underlying these traits may help researchers to obtain improved cultivars through molecular breeding techniques.Results: Whole-genome resequencing of an RIL population of 318 lines was performed to construct a high-density linkage map and identify QTLs for peanut quality. The map, containing 4561 bin markers, covered a length of 2032.39 cM with an average marker density of 0.45 cM. A total of 109 QTLs for oil content, protein content, and fatty acid compositions were mapped on the 18 peanut chromosomes. The QTL qA05.1 was detected in four different environments and exhibited a major phenotypic effect on the content of oil, proteins, and six fatty acids. The genomic region spanned by qA05.1, corresponding to a physical interval of approximately 1.50 Mb, contains two polymorphic SNPs between two parents that could cause missense mutations. The two SNP sites were employed as KASP markers and validated using lines with extremely high and low oil contents; these sites may be useful in the marker-assisted breeding of peanut varieties with high oil contents.Conclusions: A high-density genetic map with 4561 bin markers was constructed, and a major and pleiotropic QTL located on LG05 was stably detected for oil, protein and fatty acids across four different environments.

Background Web blotch is one of the most important foliar diseases worldwide in peanut (Arachis hypogaea L.). The identification of quantitative trait loci (QTLs) for peanut web blotch resistance represents the basis for gene mining and the application of molecular breeding technologies. Results In this study, a peanut recombinant inbred line (RIL) population was used to map QTLs for web blotch resistance based on high-throughput genome-wide sequencing. Frequency distributions of disease grade and disease index in five environments indicated wide phenotypic variations in response to web blotch among RILs. A high-density genetic map was constructed, containing 3634 bin markers distributed on 20 peanut linkage groups (LGs) with an average genetic distance of 0.5 cM. In total, eight QTLs were detected for peanut web blotch resistance in at least two environments, explaining from 2.8 to 15.1% of phenotypic variance. Two major QTLs qWBRA04 and qWBRA14 were detected in all five environments and were linked to 40 candidate genes encoding nucleotide-binding site leucine-rich repeat (NBS-LRR) or other proteins related to disease resistances. Conclusions The results of this study provide a basis for breeding peanut cultivars with web blotch resistance.

Using cotyledons as explants a new method of peanut regeneration was established via somatic embryogenesis (SE), involving a kind of first-observed SE structure that was shaped like bulbil and therefore named bulbil-like body (BLB). On Murashige and Skoog (MS) media containing a higher concentration of 2,4-D (20.0 mg/L) and incubated in the dark, all the inoculated cotyledon explants formed BLBs with a high frequency of average 26 BLBs per cotyledon explant, and 100.00 % of the formed BLBs spontaneously developed into multiple shoots (3–5 shoots per BLB) without changing induction and incubation conditions. On average, about 103 shoots can be induced from an individual cotyledon explant. On MS media supplemented with 1.0 mg/L NAA all the separated shoots formed normal roots to develop into plantlets. The morphological and histological analyses of BLBs at different development stages revealed that BLB was a special kind of SE structure originated from cortex cells of peanut cotyledon explants, and each individual BLB was composed of multiple embryoids further developing into multiple shoots. To our knowledge, BLB is a novel type of SE structure in peanut different from the known SE structures because of its special shape, induction conditions, somatic embryogenic nature, and multiple-embryoid characteristics.

Due to the low flow rate measurement demand for battery-powered electromagnetic water meter, shrunk measurement tubes (such as circular section transition to square section) are often used to enhance flow velocity and measurement performance at small flow rate. However, this will also result in an increase in sensor pressure loss, even exceeding the pressure loss limit. Therefore, it is necessary to study a flow tube structure design method based on pressure loss-flow restriction, and design a flow tube structure which can not only maximize the induced voltage, but also meet the actual pressure loss requirement. Because there are many unknown variables in the formula of pressure loss mechanism, it cannot be directly used in structural design. Therefore, taking DN100 sensor as an example, based on finite element software, the variation of pressure loss with the length, width and height of rectangular section is obtained by orthogonal test method, and the numerical model of pressure loss is established. According to the requirements of industry and induced voltage enhancement, the optimal rectangular section size is found with the established pressure loss numerical model, and the structure of flow tube transition section is further optimized to reduce pressure loss. Finally, the prototype is made according to the optimized structure. Pressure loss experiment shows that the error between simulated value and measured value is within ±2.68% (±0.4 KPa). It means the pressure loss-flow restriction based design method for flow tube structure of electromagnetic water meter with shrunk measurement tube is effective and reliable.