有性杂交是花生(Arachis hypogaea L.)育种的重要途径,真杂种鉴定对于遗传群体的构建以及新品种选育至关重要.花生含油量的表型鉴定极易受到环境条件的影响,且目前缺少可用的分子标记.本研究选用高油及普通油酸亲本宇花14号与低油及高油酸亲本LOP215杂交构建含油量相关遗传群体.宇花14号含有AhFAD2A及AhFAD2B位点,基因型为AABB,LOP215含有AhFAD2a及AhFAD2b位点,基因型为aabb.以宇花14号为母本、LOP215为父本杂交,收获F1杂交籽仁,采用竞争性等位基因特异性PCR(Kompetitive Allele Specific PCR,KASP)检测AhFAD2基因型,剔除AhFAD2基因型为纯合的籽仁,选留FAD2基因型为杂合的F1真杂种.F1真杂种单粒播种收获后,单株检测含油量,对于F2表型无明显分离的株系,取各单株叶片等量混合后提取DNA,进行AhFAD2基因型检测再次确认AhFAD2位点的杂合性.经二次验证后的F2籽粒经连续自交6代后选育出包含460个家系的重组自交系(recombinant inbred lines,RIL)群体,其含油量呈连续正态分布,可作为含油量基因定位的有效分离群体.本试验以AhFAD2作为选择标记能简单高效地筛选出真杂种,构建目标性状分离群体,为花生含油量基因定位及高低油花生品种选育提供材料.

Peanut ( Arachis hypogaea L.) is an important crop used for oil production, and oleic acid is a major factor in determining oil quality. Alterations in the oleic acid content can improve the nutritional quality and oxidative stability and prolong the shelf life of peanut products. The objective of this study was to develop a peanut variety with a high-oleic-acid content and high yield. One elite variety, “huayu22,” was hybridized with the high-oleic-acid “KN176” donor and backcrossed for four generations as the recurrent parent using fad2 marker-assisted backcross selection. Based on the Kompetitive allele-specific PCR (KASP) screening of fad2 markers, the oleic acid content of advanced generations derived by selfing was assessed by near-infrared reflectance spectroscopy and gas chromatography. The genetic background recovery rate of four BC 4 F 4 lines showed an average of 92.34% and was confirmed by genotyping using the Axiom_ Arachis 58 K SNP array. Across these superior lines in BC 4 F 6 generations, one line with a high-oleic-acid content and high yield was detected and named “YH61.” In particular, yield comparison experiments showed that YH61 exhibited high and stable yield at three different locations and was moderately resistant to leaf spot disease. The distinctness, uniformity and stability (DUS) testing for two consecutive years suggested that YH61 reached the standard for variety rights application. The use of the peanut variety YH61 contributed to the expansion of the cultivation area due to its high value in the oleic acid market and the proven economic benefits in China. This study demonstrated that the marker-assisted backcross strategy based on a cost-effective KASP assay and SNP array for the detection of mutations in fad2 and genetic background evaluation can be used to create efficient peanut breeding programs and contribute to oil quality and high-yield stability.

Background The cultivated peanut ( Arachis hypogaea L., AABB) is an allotetraploid hybrid between two diploid peanuts, A. duranensis (AA genome) and A. ipaensis (BB genome). Miniature inverted-repeat transposable elements (MITEs), some of which are known as active nonautonomous DNA transposons with high copy numbers, play important roles in genome evolution and diversification. AhMITE1 , a member of the MITE family of transposons, but information on the peanut genomes is still limited. Here, we analyzed AhMITE1 , AuMITE1 and ApMITE1 in the cultivated ( A. hypogaea ) and two wild peanut ( A. duranensis and A. ipaensis ) genomes. Results The cultivated and the two wild peanut genomes harbored 142, 14 and 21 AhMITE1 , AuMITE1 and ApMITE1 family members, respectively. These three family members exhibited highly conserved TIR sequences, and insertions preferentially occurred within 2 kb upstream and downstream of gene-coding and AT-rich regions. Phylogenetic and pairwise nucleotide diversity analysis showed that AhMITE1 and ApMITE1 family members have undergone one round of amplification bursts during the evolution of the peanut genome. PCR analyses were performed in 23 peanut varieties and demonstrated that AhMITE1 is an active transposon and that hybridization or chemical mutagenesis can promote the mobilization of AhMITE1 . Conclusions AhMITE1 , AuMITE1 and ApMITE1 family members were identified based on local BLAST search with MAK between the cultivated and the two wild peanut genomes. The phylogenetic, nucleotide diversity and variation copy numbers of AhMITE1 , AuMITE1 and ApMITE1 members provides opportunities for investigating their roles during peanut evolution. These findings will contribute to knowledge on diversity of AhMITE1 , provide information about the potential impact on the gene expression and promote the development of DNA markers in peanut.

Peanut (Arachis hypogaea L.) is an allotetraploid oilseed crop worldwide due to its abundant high-quality oil production. Peanut oil stability and quality are determined by the relative proportions of saturated fatty acids (SFAs) and unsaturated fatty acids (UFAs). The principle approach to minimize the content of SFAs in peanut is to reduce the content of palmitic acid, which is linked to cardiovascular disease. Acyl-acyl carrier protein thioesterases (FATs) determine the types and levels of fatty acids that are exported them from the plastids. Two different classes of FAT have been classified into two families in plants, FatA and FatB. Among them, AhFatB has become the primary objective to genetically reduce the content of palmitic acid in peanut. Here, we identified 18 AhFatB genes in A. hypogaea genome and grouped into four major subfamilies through gene structures and phylogenetic relationships. Expression profiling of AhFatB genes was assessed using the publicly available RNA-seq data and qRT-PCR in 22 tissues. Using the CRISPR/Cas9 system, we designed two sgRNAs to edit the homologs AhFatB genes Arahy.4E7QKU and Arahy.L4EP3N, and identified different types of mutations. Additionally, we discovered mutations at Arahy.4E7QKU exhibited low palmitic acid and high oleic acid phenotypes. The obtained peanut mutants with altered SFAs content have great potential for improving peanut oil quality for human health.

花生(Arachis hypogaea L.)籽仁含油量是花生品质评价的重要指标,建立快速高效的含油量检测方法,对加快高油花生品种选育意义重大.本研究选用高油亲本宇花14(含油量59.32％)与低油亲本LOP215(含油量48.97％)杂交构建的RIL群体为建模材料,使用Thermo公司(美国)生产的AntarisⅡ型傅立叶变换近红外光谱分析仪对229份样品籽仁进行光谱采集,随后测定籽仁含油量.利用偏最小二乘法(partial least squares,PLS)构建花生籽仁含油量近红外定标模型,该模型的内部验证均方差(root mean square error of cross validation,RMSECV)为0.885,相关系数R2=0.9147.选用未参与建模的21份花生材料对该模型进行外部验证,模型预测值和化学测定值的决定系数R2=0.9492,表明该模型可适用于花生籽仁含油量检测.利用该模型对宇花14与LOP215杂交后代群体进行筛选,获得含油量超过55％的优良株系21个,含油量低于48％的株系9个,可为花生高低含油量品种选育提供种质材料.