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As an important factor affecting the edible quality of peanut kernels, sucrose content is a complex quantitative trait regulated by multiple factors. In this study, an F2 segregating population and a recombinant inbred line (RIL) population, derived from a cross between the high sucrose content variety Jihuatian 1 and the low sucrose content line PI478819, were used as materials to map a quantitative trait locus (QTL) associated with sucrose content in peanut kernels. Four QTLs were initially located on chromosomes A03 and A06 based on BSA-seq technology, and multiple kompetitive allele-specific PCR markers were developed based on single-nucleotide polymorphisms (SNPs) in the intervals. The markers were genotyped in the RIL population and finely mapped to a stable QTL, qSUCA06, located on chromosome A06 within a 0.29-Mb physical genomic interval (112367085–112662675 bp), which accounted for 31.95%–41.05% of the phenotypic variance explained. SNP and insertion/deletion annotations were performed on genes in the candidate interval, and having screened out those genes with mutations in exons, candidate genes were verified by qRT-PCR. The results revealed that Arahy.Y2LWD9 may be the main gene regulating sucrose content. The QTL identified in this study will not only contribute to marker-assisted breeding for improvement of peanut sucrose content but also paves the way for identifying gene function.

To understand the performance of ecological pervious concrete prepared with mixed sandstone/limestone aggregates, limestone and sandstone were used as two aggregates. The sandstone-to-limestone volume ratio was calculated in 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0 in coarse aggregate to prepare ecological pervious concrete specimens. The compressive test, water permeability test, cooling test, evaporation test, alkaline test, and scanning electron microscope (SEM) tests were carried out with qualified compressive strength as the indicator to determine the optimum sandstone-to-limestone volume ratio for the ecological pervious concrete. The results show that the water permeability, cooling property, and evaporation property of the ecological pervious concrete increase with the sandstone content. When the sandstone-to-limestone volume ratio is less than 0.32 : 0.68 (the substitution rate of sandstone for limestone in ecological pervious concrete is 32%), the strength of ecological pervious concrete meets the requirements of 5 MPa and achieves the best permeability coefficient of 9 mm/s. This realizes the full use of net water storage and cooling capacity of the ecological pervious concrete and makes the ecological pervious concrete meet the construction requirement of slope protection in sponge cities in the south.

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.

Background Chromosomal variants play important roles in crop breeding and genetic research. The development of single-stranded oligonucleotide (oligo) probes simplifies the process of fluorescence in situ hybridization (FISH) and facilitates chromosomal identification in many species. Genome sequencing provides rich resources for the development of oligo probes. However, little progress has been made in peanut due to the lack of efficient chromosomal markers. Until now, the identification of chromosomal variants in peanut has remained a challenge. Results A total of 114 new oligo probes were developed based on the genome-wide tandem repeats (TRs) identified from the reference sequences of the peanut variety Tifrunner (AABB, 2n = 4x = 40) and the diploid species Arachis ipaensis (BB, 2n = 2x = 20). These oligo probes were classified into 28 types based on their positions and overlapping signals in chromosomes. For each type, a representative oligo was selected and modified with green fluorescein 6-carboxyfluorescein (FAM) or red fluorescein 6-carboxytetramethylrhodamine (TAMRA). Two cocktails, Multiplex #3 and Multiplex #4, were developed by pooling the fluorophore conjugated probes. Multiplex #3 included FAM-modified oligo TIF-439, oligo TIF-185-1, oligo TIF-134-3 and oligo TIF-165. Multiplex #4 included TAMRA-modified oligo Ipa-1162, oligo Ipa-1137, oligo DP-1 and oligo DP-5. Each cocktail enabled the establishment of a genome map-based karyotype after sequential FISH/genomic in situ hybridization (GISH) and in silico mapping. Furthermore, we identified 14 chromosomal variants of the peanut induced by radiation exposure. A total of 28 representative probes were further chromosomally mapped onto the new karyotype. Among the probes, eight were mapped in the secondary constrictions, intercalary and terminal regions; four were B genome-specific; one was chromosome-specific; and the remaining 15 were extensively mapped in the pericentric regions of the chromosomes. Conclusions The development of new oligo probes provides an effective set of tools which can be used to distinguish the various chromosomes of the peanut. Physical mapping by FISH reveals the genomic organization of repetitive oligos in peanut chromosomes. A genome map-based karyotype was established and used for the identification of chromosome variations in peanut following comparisons with their reference sequence positions.