Background Long noncoding RNAs (lncRNAs) have several known functions involving various biological regulatory processes in plant. However, the possible roles of lncRNAs during peanut seed development have not been fully explored. Results In this study, two peanut recombinant inbred lines (RIL8) that differ in seed size were used to investigate comprehensive lncRNA profiles derived from the seed development at 15 and 35 days after flowering (DAF). We identified a total of 9388 known and 4037 novel lncRNAs, from which 1437 were differentially expressed lncRNAs. Interestingly, the expression patterns of a number of lncRNAs can be very different between two closely related inbred lines and these lncRNAs were expressed predominantly in only one RIL at 35 DAF. Some differentially expressed lncRNAs were found related to putative cis-acting target genes and predicted to be involved in transcription, transport, cell division, and plant hormone biosynthesis. The expression patterns of several representative lncRNAs and 12 protein-coding genes were validated by qPCR. Same expression pattern was observed between most lncRNAs and their target genes. 11 lncRNAs, XR_001593099.1, MSTRG.18462.1, MSTRG.34915.1, MSTRG.41848.1, MSTRG.22884.1, MSTRG.12404.1, MSTRG.26719.1, MSTRG.35761.1, MSTRG.20033.1, MSTRG.13500.1, and MSTRG.9304.1 and their cis-acting target genes may play key roles in peanut seed development. Conclusions These results provided new information on lncRNA-mediated regulatory roles in peanut seed development, contributing to the comprehensive understanding of the molecular mechanisms involved in peanut seed development.

Additional file 4: Table S4. Differentially expressed known and novel lncRNAs four comparisons. (S4–1) Differentially expressed lncRNAs in RIL8106 at 35 DAF (T1 vs C1). (S4–2) Differentially expressed lncRNAs in RIL8107 at 35 DAF (T2 vs C2). (S4–3) Differentially expressed lncRNAs in C2 vs C1. (S4–4) Differentially expressed lncRNAs in T2 vs T1.

为了能够高效快速提取群体花生DNA,本研究在碱裂解法的基础上进一步简化步骤,以不同浓度NaOH溶液为提取液,采用直接吸取上清进行PCR和吸取部分上清中和后进行PCR,分析了两种方法的提取效果.结果 表明,用1.000 mol/L NaOH溶液裂解后,吸取部分上清中和后的DNA扩增效果更好,与用SLS常规法提取的DNA质量效果相同.该方法简便快捷,在很短的时间内能够提取大量花生群体材料的DNA,并具有较高的稳定性,可在花生分子标记辅助选择育种中广泛应用,为不同基因型花生的高通量快速筛选奠定了基础.

ω-6脂肪酸脱氢酶控制花生中油酸向亚油酸的转化,该酶由AhFAD2基因编码.为了研究Ah-FAD2基因的功能,本研究根据前期已经克隆得到的AhFAD2基因序列,设计了gRNA前导序列,并构建了CRISPR/Cas9基因编辑载体,通过双酶切和Sanger测序确定载体构建成功.AhFAD2基因CRISPR/Cas9载体的构建为接下来的遗传转化及研究该基因的功能奠定了基础.

Like many important crops, peanut is a polyploid that underwent polyploidization, evolution, and domestication. The wild allotetraploid peanut species Arachis monticola (A. monticola) is an important and unique link from the wild diploid species to cultivated tetraploid species in the Arachis lineage. However, little is known about A. monticola and its role in the evolution and domestication of this important crop. A fully annotated sequence of ≈2.6 Gb A. monticola genome and comparative genomics of the Arachis species is reported. Genomic reconstruction of 17 wild diploids from AA, BB, EE, KK, and CC groups and 30 tetraploids demonstrates a monophyletic origin of A and B subgenomes in allotetraploid peanuts. The wild and cultivated tetraploids undergo asymmetric subgenome evolution, including homoeologous exchanges, homoeolog expression bias, and structural variation (SV), leading to subgenome functional divergence during peanut domestication. Significantly, SV-associated homoeologs tend to show expression bias and correlation with pod size increase from diploids to wild and cultivated tetraploids. Moreover, genomic analysis of disease resistance genes shows the unique alleles present in the wild peanut can be introduced into breeding programs to improve some resistance traits in the cultivated peanuts. These genomic resources are valuable for studying polyploid genome evolution, domestication, and improvement of peanut production and resistance.

Background Circular RNAs (circRNAs), a class of widely expressed endogenous regulatory RNAs, are involved in diverse physiological and developmental processes in eukaryotic cells. However, there have been no related studies on the number of circRNAs and their overall characteristics including circRNA abundance and expression profiles in peanut, which is one of the most important edible oil seed crops in the world. Results We performed a genome-wide identification of circular RNAs using ribosomal-depleted RNA-sequencing from the seeds of two peanut eighth-generation recombinant inbred lines (RIL8): ‘RIL 8106’ (a medium-pod variety) and ‘RIL 8107’ (a super-pod variety), at 15 and 35 days after flowering (DAF), respectively. A total of 347 circRNA candidates were detected by two computational pipelines: CIRCexplorer and CIRI, with at least two supporting junction reads. All these circRNAs were generated from exons of annotated genes, and widespread on the 20 peanut chromosomes. The expression profiles revealed that circRNAs were differentially expressed between two stages and between two lines. GO enrichment analysis of the host genes produced differentially-expressed circRNAs suggested that circRNAs are involved in seed development and regulation of seed size. Fifteen circRNAs were experimentally analyzed by qRT-PCR with divergent primers, and six circRNAs were resistant to digestion with RNase R exonuclease, and the back-splicing sites were further validated by Sanger DNA sequencing. Conclusions We present the first systematical investigation of the genomic characteristics and expression profiles of circRNAs in peanut. The results revealed that circRNAs are abundant and widespread in peanut, and the differentially-expressed circRNAs between two lines suggested that they might play regulatory roles in peanut seeds development.

Growth-regulating factors (GRFs) are plant-specific transcription factors that perform important functions in plant growth and development. Herein, we identified and characterised 24 AhGRF genes in peanut (Arachis hypogaea). AhGRF family genes were divided into six classes with OLQ and WRC domains. Transcriptome expression profile showed that more AhGRF genes, such as AhGRF5a gene, were at higher expression during pod development in Arachis monticola than cultivated species, especially at the pod rapid-expansion stage. AhGRF5a and AhGRF5b genes expressed at higher levels in pods than roots, leaves and stems tissues, existing in the difference between Arachis monticola and H8107. Exogenous GA3 application can activate AhGRF5a and AhGRF5b genes and H8107 line showed more positive response than Arachis monticola species. These results imply that these two AhGRF genes may be active during the peanut pod development.

本试验以花生品系花7616为父本、H1338为母本杂交得到的F1代群体为材料,利用AhMITE标记对F1代真伪杂种进行鉴定.结果 表明:F1代群体78个单株中有8株呈现母本单一条带,50株呈现父本单一条带,20株是双亲杂合带型;结合父母本叶片表型特征,共有20个单株鉴定为真杂种,真杂种率为25.64％,与分子标记鉴定结果一致.综上,利用转座子分子标记可以准确地对杂交后代进行鉴定,进而为高世代RIL群体的构建奠定基础.

Seed expansion in peanut is a complex biological process involving many gene regulatory pathways. MicroRNAs (miRNAs) play important regulatory roles in plant growth and development, but little is known about their functions during seed expansion, or how they contribute to seed expansion in different peanut lines. We examined seed miRNA expression patterns at 15 and 35 days after flowering (DAF) in two peanut eighth-generation recombinant inbred lines (RIL8); 8106, a medium-pod variety, and 8107, a super-pod variety. Using high-throughput sequencing, we identified 1,082 miRNAs in developing peanut seeds including 434 novel miRNAs. We identified 316 differentially expressed miRNAs by comparing expression levels between the two peanut lines. Interestingly, 24 miRNAs showed contrasting patterns of expression in the two RILs, and 149 miRNAs were expressed predominantly in only one RIL at 35 DAF. Also, potential target genes for some conserved and novel miRNAs were identified by degradome sequencing; target genes were predicted to be involved in auxin mediated signaling pathways and cell division. We validated the expression patterns of some representative miRNAs and 12 target genes by qPCR, and found negative correlations between the expression level of miRNAs and their targets. miR156e, miR159b, miR160a, miR164a, miR166b, miR168a, miR171n, miR172c-5p, and miR319d and their corresponding target genes may play key roles in seed expansion in peanut. The results of our study also provide novel insights into the dynamic changes in miRNAs that occur during peanut seed development, and increase our understanding of miRNA function in seed expansion.

Arachis monticola (2n = 4x = 40) is the only allotetraploid wild peanut within the Arachis genus and section, with an AABB-type genome of ∼2.7 Gb in size. The AA-type subgenome is derived from diploid wild peanut Arachis duranensis, and the BB-type subgenome is derived from diploid wild peanut Arachis ipaensis. A. monticola is regarded either as the direct progenitor of the cultivated peanut or as an introgressive derivative between the cultivated peanut and wild species. The large polyploidy genome structure and enormous nearly identical regions of the genome make the assembly of chromosomal pseudomolecules very challenging. Here we report the first reference quality assembly of the A. monticola genome, using a series of advanced technologies. The final whole genome of A. monticola is ∼2.62 Gb and has a contig N50 and scaffold N50 of 106.66 Kb and 124.92 Mb, respectively. The vast majority (91.83%) of the assembled sequence was anchored onto the 20 pseudo-chromosomes, and 96.07% of assemblies were accurately separated into AA- and BB- subgenomes. We demonstrated efficiency of the current state of the strategy for de novo assembly of the highly complex allotetraploid species, wild peanut (A. monticola), based on whole-genome shotgun sequencing, single molecule real-time sequencing, high-throughput chromosome conformation capture technology, and BioNano optical genome maps. These combined technologies produced reference-quality genome of the allotetraploid wild peanut, which is valuable for understanding the peanut domestication and evolution within the Arachis genus and among legume crops.