Effects of different precursors on the structure of lignin-based biochar and its ability to adsorb benzopyrene from sesame oil.

Agricultural by-products of sesame are promising bioresources in food processing. This study extracted lignin from the by-products of sesame oil production, namely, the capsules and straw of black and white sesame. Using acid, alkali, and ethanol methods, 12 distinct lignins were obtained to prepare biochar, aiming to investigate both the structural characteristics of lignin-based biochar (LBB) and its ability to remove benzo[a]pyrene (BaP) from sesame oil. The results showed that white sesame straw was the most suitable raw material for preparing biochar. In terms of the preparation method, acid-extracted lignin biochar was more effective in removing BaP than alkaline or ethanol methods. Notably, WS-1LB (white sesame straw acid-extracted lignin biochar) exhibited the highest BaP adsorption efficiency (91.44 %) and the maximum specific surface area (1065.8187 m2/g), characterized by porous structures. The pseudo 2nd and Freundlich models were found to be the best fit for the adsorption kinetics and isotherms of BaP on LBB, respectively, suggesting that a multilayer adsorption process was dominant. The high adsorption of LBB mainly resulted from pore filling. This study provides an economical and highly efficient biochar adsorbent for the removal of BaP in oil.

Comparison of methods for activating sesame stalk lignin biochar for removing benzo[a]pyrene from sesame oil.

In this study, three activators and two activation methods were employed to activate sesame lignin-based biochar. The biochar samples were comprehensively characterized, their abilities to adsorb benzo[a]pyrene (BaP) from sesame oil were assessed, and the mechanism was analyzed. The results showed that the biochar obtained by one-step activation was more effective in removing BaP from sesame oil than the biochar produced by two-step activation. Among them, the biochar generated by one-step activation with ZnCl2 as the activator had the largest specific surface area (1068.8776 m3/g), and the richest mesoporous structure (0.7891 m3/g); it removed 90.53 % of BaP from sesame oil. BaP was mainly adsorbed by the mesopores of biochar. Mechanistically, pore-filling, π-π conjugations, hydrogen bonding, and n-π interactions were involved. The adsorption was spontaneous and heat-absorbing. In conclusion, the preparation of sesame lignin biochar using one-step activation with ZnCl2 as the activator was found to be the best for removing BaP from sesame oil. This biochar may be an economical adsorbent for the industrial removal of BaP from sesame oil.

Characterization of aroma-active compounds in sesame hulls at different roasting temperatures by SAFE and GC-O-MS.

The study characterized the aroma-active compounds produced by sesame hulls at three roasting temperatures and analyzed the similarities and differences in the aroma profile of sesame hulls with whole seeds and kernels after roasting. Roasting hulls produced mainly furans, aldehydes, and ketones volatiles. 140 Compounds were identified as aroma-active compounds, including 36 key aroma compounds (odor activity value, OAV ≥ 1). Among them, furanone (caramel-like, OAV = 80), 3-methylbutanal (fruity, OAV = 124), and 2-methoxy-4-vinylphenol (burnt, smoky, OAV = 160) gave hulls (180 °C) sweet, burnt, and smoky aroma. Due to the contribution of vanillin (fatty, sweet milk, OAV = 45), 2-hydroxy-3-butanone (caramel-like, roast, OAV = 46), and 2-methoxy-4-vinylphenol (OAV = 78), hulls (200 °C) shown strong sweet and roast note. These results identified compounds that contributed significantly to the aroma of sesame hulls and elucidated the contribution of sesame hulls to the flavor of roasted whole seeds and sesame oil.

Genomic evolution and insights into agronomic trait innovations of Sesamum species.

Sesame is an ancient oilseed crop with high oil content and quality. However, the evolutionary history and genetic mechanisms of its valuable agronomic traits remain unclear. Here, we report chromosome-scale genomes of cultivated sesame (Sesamum indicum L.) and six wild Sesamum species, representing all three karyotypes within this genus. Karyotyping and genome-based phylogenic analysis revealed the evolutionary route of Sesamum species from n = 13 to n = 16 and revealed that allotetraploidization occurred in the wild species Sesamum radiatum. Early divergence of the Sesamum genus (48.5-19.7 million years ago) during the Tertiary period and its ancient phylogenic position within eudicots were observed. Pan-genome analysis revealed 9164 core gene families in the 7 Sesamum species. These families are significantly enriched in various metabolic pathways, including fatty acid (FA) metabolism and FA biosynthesis. Structural variations in SiPT1 and SiDT1 within the phosphatidyl ethanolamine-binding protein gene family lead to the genomic evolution of plant-architecture and inflorescence-development phenotypes in Sesamum. A genome-wide association study (GWAS) of an interspecific population and genome comparisons revealed a long terminal repeat insertion and a sequence deletion in DIR genes of wild Sesamum angustifolium and cultivated sesame, respectively; both variations independently cause high susceptibility to Fusarium wilt disease. A GWAS of 560 sesame accessions combined with an overexpression study confirmed that the NAC1 and PPO genes play an important role in upregulating oil content of sesame. Our study provides high-quality genomic resources for cultivated and wild Sesamum species and insights that can improve molecular breeding strategies for sesame and other oilseed crops.

QTL analysis of traits related to seed size and shape in sesame (Sesamum indicum L.).

Seed size and shape are important traits that determine seed yield in sesame. Understanding the genetic basis of seed size and shape is essential for improving the yield of sesame. In this study, F2 and BC1 populations were developed by crossing the Yuzhi 4 and Bengal small-seed (BS) lines for detecting the quantitative trait loci (QTLs) of traits related to seed size and shape. A total of 52 QTLs, including 13 in F2 and 39 in BC1 populations, for seed length (SL), seed width (SW), and length to width ratio (L/W) were identified, explaining phenotypic variations from 3.68 to 21.64%. Of these QTLs, nine stable major QTLs were identified in the two populations. Notably, three major QTLs qSL-LG3-2, qSW-LG3-2, and qSW-LG3-F2 that accounted for 4.94-16.34% of the phenotypic variations were co-localized in a 2.08 Mb interval on chromosome 1 (chr1) with 279 candidate genes. Three stable major QTLs qSL-LG6-2, qLW-LG6, and qLW-LG6-F2 that explained 8.14-33.74% of the phenotypic variations were co-localized in a 3.27 Mb region on chr9 with 398 candidate genes. In addition, the stable major QTL qSL-LG5 was co-localized with minor QTLs qLW-LG5-3 and qSW-LG5 to a 1.82 Mb region on chr3 with 195 candidate genes. Gene annotation, orthologous gene analysis, and sequence analysis indicated that three genes are likely involved in sesame seed development. These results obtained herein provide valuable in-formation for functional gene cloning and improving the seed yield of sesame.

Genetic mapping of QTLs controlling brown seed coat traits by genome resequencing in sesame (Sesamum indicum L.).

Introduction: Sesame seeds have become an irreplaceable source of edible oils and food products with rich nutrients and a unique flavor, and their metabolite contents and physiological functions vary widely across different seed coat colors. Although the quantitative trait loci (QTLs) for genetic variation in seed coat color have been extensively investigated, the identification of unique genetic loci for intermediate colors such as brown has not been reported due to their complexity. Methods: Here, we crossed the white sesame 'Yuzhi No. 8' (YZ8) and the brown sesame 'Yanzhou Erhongpi' (YZEHP) to construct a recombinant inbred line (RIL) population with consecutive self-fertilization for ten generations. Results: The selfed F1 seeds were brown which was controlled by a dominant gene. Based on the genotyping by whole-genome resequencing of the RILs, a major-effect QTL for brown coat color was identified through both bulk segregant analysis (BSA) and genetic linkage mapping in sesame, which was located within a 1.19 Mb interval on chromosome 6 (qBSCchr6). Moreover, we found that the YZEHP seed coat initially became pigmented at 20 days post-anthesis (DPA) and was substantially colored at 30 DPA. We screened 13 possible candidate genes based on the effects of genetic variants on protein coding and predicted gene functions. Furthermore, qRT‒PCR was used to verify the expression patterns of these genes in different post-anthesis developmental periods. We noted that in comparison to YZ8 seeds, YZEHP seeds had expression of SIN_1023239 that was significantly up-regulated 2.5-, 9.41-, 6.0-, and 5.9-fold at 15, 20, 25, and 30 DPA, respectively, which was consistent with the pattern of brown seed coat pigment accumulation. Discussion: This study identified the first major-effect QTL for the control of the brown seed coat trait in sesame. This finding lays the foundation for further fine mapping and cloning as well as investigating the regulatory mechanism of seed coat color in sesame.

Genome-wide association study of seed coat color in sesame (Sesamum indicum L.).

Sesame (Sesamum indicum L.) is an important and ancient oilseed crop. Sesame seed coat color is related to biochemical functions involved in protein and oil metabolism, and antioxidant content. Because of its complication, the genetic basis of sesame seed coat color remains poorly understood. To elucidate the factors affecting the genetic architecture of seed coat color, 366 sesame germplasm lines were evaluated for seed coat color in 12 environments. The genome-wide association studies (GWAS) for three seed coat color space values, best linear unbiased prediction (BLUP) values from a multi-environment trial analysis and principal component scores (PCs) of three seed coat color space values were conducted. GWAS for three seed coat color space values identified a total of 224 significant single nucleotide polymorphisms (SNPs, P < 2.34×10-7), with phenotypic variation explained (PVE) ranging from 1.01% to 22.10%, and 35 significant SNPs were detected in more than 6 environments. Based on BLUP values, 119 significant SNPs were identified, with PVE ranging from 8.83 to 31.98%. Comparing the results of the GWAS using phenotypic data from different environments and the BLUP values, all significant SNPs detected in more than 6 environments were also detected using the BLUP values. GWAS for PCs identified 197 significant SNPs, and 30 were detected in more than 6 environments. GWAS results for PCs were consistent with those for three color space values. Out of 224 significant SNPs, 22 were located in the confidence intervals of previous reported quantitative trait loci (QTLs). Finally, 92 candidate genes were identified in the vicinity of the 4 SNPs that were most significantly associated with sesame seed coat color. The results in this paper will provide new insights into the genetic basis of sesame seed coat color, and should be useful for molecular breeding in sesame.

QTL mapping of yield-related traits in sesame.

Improving yield is one of the most important targets of sesame breeding. Identifying quantitative trait loci (QTLs) of yield-related traits is a prerequisite for marker-assisted selection (MAS) and QTL/gene cloning. In this study, a BC1 population was developed and genotyped with the specific-locus amplified fragment (SLAF) sequencing technology, and a high-density genetic map was constructed. The map consisted of 13 linkage groups, contained 3528 SLAF markers, and covered a total of 1312.52 cM genetic distance, with an average distance of 0.37 cM between adjacent markers. Based on the map, 46 significant QTLs were identified for seven yield-related traits across three environments. These QTLs distributed on 11 linkage groups, each explaining 2.34-71.41% of the phenotypic variation. Of the QTLs, 23 were stable QTLs that were detected in more than one environment, and 20 were major QTLs that explained more than 10% of the corresponding phenotypic variation in at least one environment. Favorable alleles of 38 QTLs originated from the locally adapted variety, Yuzhi 4; the exotic germplasm line, BS, contributed favorable alleles to only 8 QTLs. The results should provide useful information for future molecular breeding and functional gene cloning. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01236-x.

Corrigendum: Genetic Diversity, Population Structure, and Linkage Disequilibrium of an Association-Mapping Panel Revealed by Genome-Wide SNP Markers in Sesame.

[This corrects the article on p. 1189 in vol. 8, PMID: 28729877.].

Genetic Diversity, Population Structure, and Linkage Disequilibrium of an Association-Mapping Panel Revealed by Genome-Wide SNP Markers in Sesame.

The characterization of genetic diversity and population structure can be used in tandem to detect reliable phenotype-genotype associations. In the present study, we genotyped a set of 366 sesame germplasm accessions by using 89,924 single-nucleotide polymorphisms (SNPs). The number of SNPs on each chromosome was consistent with the physical length of the respective chromosome, and the average marker density was approximately 2.67 kb/SNP. The genetic diversity analysis showed that the average nucleotide diversity of the panel was 1.1 × 10-3, with averages of 1.0 × 10-4, 2.7 × 10-4, and 3.6 × 10-4 obtained, respectively for three identified subgroups of the panel: Pop 1, Pop 2, and the Mixed. The genetic structure analysis revealed that these sesame germplasm accessions were structured primarily along the basis of their geographic collection, and that an extensive admixture occurred in the panel. The genome-wide linkage disequilibrium (LD) analysis showed that an average LD extended up to ∼99 kb. The genetic diversity and population structure revealed in this study should provide guidance to the future design of association studies and the systematic utilization of the genetic variation characterizing the sesame panel.

High-Density Genetic Map Construction and Gene Mapping of Basal Branching Habit and Flowers per Leaf Axil in Sesame.

A good genetic map can provide the framework for quantitative trait loci (QTL) analysis, map-based gene cloning, and genome sequence assembling. The main objectives of this study were to develop a high-density genetic linkage map using specific length amplified fragment sequencing (SLAF-seq) in sesame. In the result, a high-resolution genetic map with 9,378 SLAF markers and 13 linkage groups (LGs) was constructed. The map spanned a total genetic distance of 1,974.23 cM, and the mean LG length was 151.86 cM, with an average genetic distance of 0.22 cM between adjacent markers. Based on the newly constructed genetic map, genes for basal branching habit (SiBH) and flowers per leaf axil (SiFA) were mapped to LG5 and LG11, respectively.

Variations and transmission of QTL alleles for yield and fiber qualities in upland cotton cultivars developed in China.

Cotton is the world's leading cash crop, and genetic improvement of fiber yield and quality is the primary objective of cotton breeding program. In this study, we used various approaches to identify QTLs related to fiber yield and quality. Firstly, we constructed a four-way cross (4WC) mapping population with four base core cultivars, Stoneville 2B, Foster 6, Deltapine 15 and Zhongmiansuo No.7 (CRI 7), as parents in Chinese cotton breeding history and identified 83 QTLs for 11 agronomic and fiber quality traits. Secondly, association mapping of agronomical and fiber quality traits was based on 121 simple sequence repeat (SSR) markers using a general linear model (GLM). For this, 81 Gossypium hirsutum L. accessions including the four core parents and their derived cultivars were grown in seven diverse environments. Using these approaches, we successfully identified 180 QTLs significantly associated with agronomic and fiber quality traits. Among them were 66 QTLs that were identified via linkage disequilibrium (LD) and 4WC family-based linkage (FBL) mapping and by previously published family-based linkage (FBL) mapping in modern Chinese cotton cultivars. Twenty eight and 44 consistent QTLs were identified by 4WC and LD mapping, and by FBL and LD mapping methods, respectively. Furthermore, transmission and variation of QTL-alleles mapped by LD association in the three breeding periods revealed that some could be detected in almost all Chinese cotton cultivars, suggesting their stable transmission and some identified only in the four base cultivars and not in the modern cultivars, suggesting they were missed in conventional breeding. These results will be useful to conduct genomics-assisted breeding effectively using these existing and novel QTL alleles to improve yield and fiber qualities in cotton.

Favorable QTL alleles for yield and its components identified by association mapping in Chinese Upland cotton cultivars.

Linkage disequilibrium based association mapping is a powerful tool for dissecting the genetic basis underlying complex traits. In this study, an association mapping panel consisting of 356 representative Upland cotton cultivars was constructed, evaluated in three environments and genotyped using 381 SSRs to detect molecular markers associated with lint yield and its components. The results showed that abundant phenotypic and moderate genetic diversities existed within this germplasm panel. The population could be divided into two subpopulations, and weak relatedness was detected between pair-wise accessions. LD decayed to the background (r(2) = 0.1182, P ≤ 0.01), r(2) = 0.1 and r(2) = 0.2 level within 12-13 cM, 17-18 cM and 3-4 cM, respectively, providing the potential for association mapping of agronomically important traits in Chinese Upland cotton. A total of 55 marker-trait associations were detected between 26 SSRs and seven lint yield traits, based on a mixed linear model (MLM) and Bonferroni correction (P ≤ 0.05/145, -log10 P ≥ 3.46). Of which 41 could be detected in more than one environment and 17 markers were simultaneously associated with two or more traits. Many associations were consistent with QTLs identified by linkage mapping in previous reports. Phenotypic values of alleles of each loci in 41 stably detected associations were compared, and 23 favorable alleles were identified. Population frequency of each favorable allele in historically released cultivar groups was also evaluated. The QTLs detected in this study will be helpful in further understanding the genetic basis of lint yield and its components, and the favorable alleles may facilitate future high-yield breeding by genomic selection in Upland cotton.

[Comparison of morphology, physiology and mineral element contents among genotypes of sesame with different tolerance to waterlogging under anaerobic condition].

The morphological and physiological indexes and the mineral element contents in different organs of 4 genotypes of sesame were examined under controlled oxygen supply. The number of adventitious roots of flooding tolerant varieties, Wild No. 7 and Yuzhi No. 1, increased 4-5 fold, the activity of ADH enhanced about twice, but the net photosynthetic rate (Pn) decreased slightly. There were significant increase in Ca and P and little decrease in K in roots, and decrease in other elements in roots and 8 elements in stems and leaves. As for less flooding-tolerant genotypes, Danbackaggce and Suiping Xiaozhihuang, however, the number of adventitious roots increased little, the activity of ADH enhanced 5-9 folds, and Pn decreased by 50-60%. An increase in Ca and P, and a significant reduction in K was found in roots. It was concluded that the waterlogging tolerance of sesame depended firstly on the structural adaptation, then on the anoxia metabolism, and that Ca and P may play an important role in the metabolic adaptation to the anaerobic environment for plant survival.