Inbred Lines Research Articles

Diversity of Major Yield Traits and Nutritional Components Among Greenhouse Grown Chickpea (Cicer arietinum L.) Breeding Lines, Landraces, and Cultivars of Different Origins

This study analyzed the diversity of major yield traits and nutritional components across 122 chickpea breeding lines, cultivars, and landraces of different origins. All parameters showed significant variations, with a variance ranging from 4.61% in days to maturity (DM) to 43.04% in oleic acid. Six accessions, including CP021, CP022, CP026, CP037, CP066, and CP109, outperformed in yield traits and nutritional value. Origin significantly affected all phenotypic traits except total fatty acid contents, with Indian and Ukrainian accessions demonstrating contrasting performances. Most traits, except for the number of seeds per pod (SPP), palmitic acid, and total fatty acid contents, differed significantly among breeding lines, cultivars, and landraces. Breeding lines were the earliest to flower and to mature with average days to flowering (DF) of 50.23 days and DM of 101.50 days. They also had the highest average SPP, number of pods per plant (PPP), total seeds per plant (TSPP), total protein, crude fiber, dietary fiber, linoleic acid, and linolenic acid contents making them preferable for high yield and nutrition. Hierarchical cluster analysis classified the chickpea accessions into seven clusters, showing significant variations in yield traits and nutritional components. Principal component and Pearson’s correlation analyses indicated positive correlations between DM and DF, and between SPP, PPP, and TSPP. Nutritional components also displayed varying associations, with a notable negative correlation between oleic and linoleic acids, the two essential fatty acids. Overall, this study showed the diversity of key phenotypic traits in chickpea breeding lines, cultivars, and landraces of different origins. The significant effects of genotype and origin differences on these traits could be used as a basis for future metabolomics and genomics research.

A MYB transcription factor underlying plant height in sorghum qHT7.1 and maize Brachytic 1 loci.

Manipulating plant height is an essential component of crop improvement. Plant height was generally reduced through breeding in wheat, rice, and sorghum to resist lodging and increase grain yield but kept high for bioenergy crops. Here, we positionally cloned a plant height quantitative trait locus (QTL) qHT7.1 as a MYB transcription factor controlling internode elongation, cell proliferation, and cell morphology in sorghum. A 740 bp transposable element insertion in the intronic region caused a partial mis-splicing event, generating a novel transcript that included an additional exon and a premature stop codon, leading to short plant height. The dominant allele had an overall higher expression than the recessive allele across development and internode position, while both alleles' expressions peaked at 46 days after planting and progressively decreased from the top to lower internodes. The orthologue of qHT7.1 was identified to underlie the brachytic1 (br1) locus in maize. A large insertion in exon 3 and a 160 bp insertion at the promoter region were identified in the br1 mutant, while an 18 bp promoter insertion was found to be associated with reduced plant height in a natural recessive allele. CRISPR/Cas9-induced gene knockout of br1 in two maize inbred lines showed significant plant height reduction. These findings revealed functional connections across natural, mutant, and edited alleles of this MYB transcription factor in sorghum and maize. This enriched our understanding of plant height regulation and enhanced our toolbox for fine-tuning plant height for crop improvement.

BoMYBL2b, an R3-MYB transcription factor, inhibits anthocyanin accumulation via directly repressing BoDFR1 gene transcription in kale

Kale is a globally popular edible and ornamental plant with colorful inner leaves. Anthocyanin is one of the most major pigments for kale. However, the underlying regulatory mechanism for the accumulation of anthocyanin in kale has not been well understood to date. Here, we characterized an R3-MYB transcription factor, BoMYBL2b, whose mRNA was missing in the anthocyanin-rich kale inbred line, but abundant in the anthocyanin-less line. Knockdown of BoMYBL2b enhanced the anthocyanin accumulation. Y1H and DLR assays showed that BoMYBL2b directly inhibited the BoDFR1 gene expression by binding to the MRE sites on the ProBoDFR1. Besides, we found that BoMYBL2b did not interact with the bHLH proteins, indicating that the BoMYBL2b might not be part of the MBW complex. BoMYBL2b expression was significantly repressed by BoMYB1R1 under high light and cold stimulus, suggesting the possibility that BoMYB1R1-BoMYBL2b module might act as a cross-node for integrating light and temperature signals to regulate anthocyanin accumulation in kale. These findings provided a theoretical basis for molecular breeding of new kale cultivars and a reference for understanding the regulatory mechanism of anthocyanin accumulation in Brassica.

The landscape of sequence variations between resistant and susceptible hot peppers to predict functional candidate genes against bacterial wilt disease

BackgroundBacterial wilt (BW), caused by Ralstonia solanacearum (Ral), results in substantial yield losses in pepper crops. Developing resistant pepper varieties through breeding is the most effective strategy for managing BW. To achieve this, a thorough understanding of the genetic information connected with resistance traits is essential. Despite identifying three major QTLs for bacterial wilt resistance in pepper, Bw1 on chromosome 8, qRRs-10.1 on chromosome 10, and pBWR-1 on chromosome 1, the genetic information of related BW pepper varieties has not been sufficiently studied. Here, we resequenced two pepper inbred lines, C. annuum ‘MC4’ (resistant) and C. annuum ‘Subicho’ (susceptible), and analyzed genomic variations through SNPs and Indels to identify candidate genes for BW resistance.ResultsAn average of 139.5 Gb was generated among the two cultivars, with coverage ranging from 44.94X to 46.13X. A total of 8,815,889 SNPs was obtained between ‘MC4’ and ‘Subicho’. Among them, 31,190 (0.35%) were non-synonymous SNPs (nsSNPs) corresponding to 10,926 genes, and these genes were assigned to 142 Gene Ontology (GO) terms across the two cultivars. We focused on three known BW QTL regions by identifying genes with sequence variants through gene set enrichment analysis and securing those belonging to high significant GO terms. Additionally, we found 310 NLR genes with nsSNP variants between ‘MC4’ (R) and ‘Subicho’ (S) within these regions. Also, we performed an Indel analysis on these genes. By integrating all this data, we identified eight candidate BW resistance genes, including two NLR genes with nsSNPs variations in qRRs-10.1 on chromosome 10.ConclusionWe identified genomic variations in the form of SNPs and Indels by re-sequencing two pepper cultivars with contrasting traits for bacterial wilt. Specifically, the four genes associated with pBWR-1 and Bw1 that exhibit both nsSNP and Indel variations simultaneously in ‘Subicho’, along with the two NLR genes linked to qRRs-10.1, which are known for their direct involvement in immune responses, are identified as most likely BW resistance genes. These variants in leading candidate genes associated with BW resistance can be used as important markers for breeding pepper varieties.

Fine mapping of a major QTL, qECQ8, for rice taste quality

BackgroundRice ECQ (eating and cooking quality) is an important determinant of rice consumption and market expansion. Therefore, improvement of ECQ is one of the primary goals in rice breeding. However, ECQ-related quantitative trait loci (QTL) have not yet been fully revealed. The present study aimed to identify a major effect QTL for rice taste, an important component of ECQ via genotyping-by-sequencing, to reveal the associated molecular mechanisms, and to predict key candidate genes.ResultsA population of F9 recombinant inbred lines resulting from a cross between R668 (national standard of high-quality third class) and R838 (common edible rice) was used to construct a high-density genetic map (2,295.062 cM). The map comprises 639,504 markers distributed on 12 linkage elements with an average genetic distance of 0.004 cM. We detected a major taste-related QTL, qECQ8, which explained 41.4% of phenotypic variance and had LOD values of 4.42–7.73. Using a five-generation NIL population from the backcross of “Ganxiangzhan No. 1” carrying qECQ8 with the recurrent parent R838 (without qECQ8), we narrowed qECQ8 to a 187.5 kb interval between markers M33 and M37 on Chr8. Comparative transcriptomic analysis revealed that photosynthesis, glyoxylate and dicarboxylate metabolism, carbon fixation in photosynthetic organisms, and alpha-linolenic acid metabolism were induced in developing seeds of lines containing qECQ8. Furthermore, we identified two candidate genes in the qECQ8 region, including LOC_Os08g30550 (zinc knuckle family protein), a major candidate for genetic-assisted breeding of high-quality rice.ConclusionOur findings provide important genetic resources for targeted improvement of rice taste quality and may facilitate the genetic breeding of rice ECQ.

Comparative Lipidomics Analysis Provides New Insights into the Metabolic Basis of Color Formation in Green Cotton Fiber

Green fiber (GF) is a naturally colored fiber. A limited understanding of its color formation mechanism restricts the improvement of colored cotton quality. This experiment used upland cotton green fiber germplasm 1-4560 and genetic inbred line TM-1; the lipid profiles of green fibers at 30 (white stage) and 35 days post-anthesis (DPA) (early greening stage), as well as those of TM-1 at the same stages, were revealed. Among the 109 differential types of lipids (DTLs) unique to GF, the content of phosphatidylserine PS (16:0_18:3) was significantly different at 30 and 35 DPA. It is speculated that this lipid is crucial for the pigment accumulation and color formation process of green fibers. The 197 DTLs unique to TM-1 may be involved in white fiber (WF) development. Among the shared DTLs in GF35 vs. GF30 and WF35 vs. WF30, sulfoquinovosyldiacyl-glycerol SQDG (18:1_18:1) displays a significant difference in the content change between green fibers and white fibers, potentially affecting color formation through changes in content. The enriched metabolic pathways in both comparison groups are relatively conserved. In the most significantly enriched glycerophospholipid metabolic pathway, 1-acyl-sn-glycero-3-phosphocholine (C04230) only appears in white cotton. This indicates differences in the metabolic pathways between white and green fibers, potentially related to different mechanisms of color formation and fiber development. These findings provide a new theoretical basis for studying cotton fiber development and offer important insights into the specific mechanism of green fiber color formation.

Mining Candidate Genes for Maize Tassel Spindle Length Based on a Genome-Wide Association Analysis

Maize tassel spindle length is closely related to the number of pollen grains and the duration of the flowering stage, ultimately affecting maize yield and adaptations to stress conditions. In this study, 182 maize inbred lines were included in an association population. A genome-wide association study was conducted on maize tassel spindle length using the Q + K model. With p ≤ 1.0 × 10−4 applied as the significance threshold, 240 SNPs significantly associated with tassel spindle length were detected, which were associated with 99 quantitative trait loci (QTLs), with 21 QTLs detected in two or more environments. Moreover, 51 candidate genes were detected in 21 co-localized QTLs. A KEGG enrichment analysis and candidate gene expression analysis indicated that Zm00001d042312 affects plant hormone signal transduction and is highly expressed in maize tassels. A haplotype analysis of Zm00001d042312 revealed three main haplotypes, with significant differences between Hap1 and Hap2. In conclusion, we propose that Zm00001d042312 is a gene that regulates maize tassel spindle length. This study has further elucidated the genetic basis of maize tassel spindle length, while also providing excellent genetic targets and germplasm resources for the genetic improvement of maize tassel spindle length and yield.

Assessment of Genetic Variability in Groundnut (Arachis hypogaea L.)

The present study was carried out with thirty advanced breeding lines of groundnut for estimation of genetic variability, heritability and genetic advance. Analysis of variance revealed highly significant differences among genotypes for all the studied characters indicating that there is substantial variability among the genotypes for these traits. High estimates of GCV and PCV was observed for pod yield per plant, kernel yield per plant, dry haulm yield per plant and number of mature pods per plant. High heritability coupled with high genetic advance as per cent of mean were recorded for number of mature pods per plant, pod yield per plant, kernel yield per plant, dry haulm yield per plant, number of immature pods per plant, plant height, harvest index and hundred kernel weight indicating the preponderance of additive gene action in expression of these traits and hence simple phenotypic selection would be effective for improvement of these characters.

Rapid estimation of DON content in wheat flour using close‐range hyperspectral imaging and machine learning

AbstractFusarium head blight (FHB) is one of the most destructive fungal diseases affecting wheat (Triticum aestivum). Moreover, it is notorious for producing mycotoxin deoxynivalenol (DON), posing a significant global threat to food and feed safety. Traditional methods like enzyme‐linked immunosorbent assay (ELISA) and gas chromatography‐mass spectrometry (GC‐MS) are commonly used to assess DON levels in grain or flour samples and are time‐consuming and expensive. Therefore, a faster, cost‐effective method to estimate DON content is needed, especially for enhancing breeding efforts to reduce DON levels in wheat. In this study, we envisioned integrating close‐range hyperspectral imaging with deep learning (DL) models to estimate DON content in wheat meal/flour. We selected 243 advanced breeding lines from the South Dakota State University (SDSU) wheat breeding program that were evaluated in FHB nurseries (2019–2020 and 2020–2021). The wheat meal samples were analyzed for DON content using GC‐MS and subsequently subjected to close‐range hyperspectral imaging. We evaluated three conventional machine learning (ML), two DL models and data augmentation. Among the conventional ML models, partial least squares regression (PLSR) (with R2P = 0.88 and 0.90 for original and augmented datasets, respectively) demonstrated the highest prediction accuracies for DON content. However, the one‐dimensional convolutional neural network (1D‐CNN) achieved the highest prediction accuracies (R2P = 0.90 and = 0.96 for original and augmented datasets, respectively) compared to all tested models and demonstrated the lowest error. In conclusion, integration of advanced hyperspectral imaging with ML approaches exhibits significant potential for high‐throughput and cost‐effective estimation of DON content in wheat, thereby accelerating wheat breeding efforts for reduced DON levels.

Shifts in plant architecture drive species-specific responses to drought in a Sorghum recombinant inbred line population.

Drought stress severely impedes plant growth, development, and yield. Therefore, it is critical to uncover the genetic mechanisms underlying drought resistance to ensure future food security. To identify the genetic controls of these responses in Sorghum, an agriculturally and economically important grain crop, an interspecific recombinant inbred line (RIL) population was established by crossing a domesticated inbred line of Sorghum bicolor (TX7000) with its wild relative, Sorghum propinquum. This RIL population was evaluated under drought conditions, allowing for theidentification of quantitative trait loci (QTL) that contribute to drought resistance. We detected eight QTL in the drought population that explain a significant portion of the observed variation for four traits (height, aboveground biomass, relative water content, and leaf temperature/transpiration). The allelic effects of, and the candidate genes within, these QTL emphasize: (1) the influence of domestication on drought-responsive phenotypes, such as height and aboveground biomass, and (2) how control of water uptake and/or loss can be driven by species-specific plant architecture. Our findings shed light on the interconnected roles of shoot and root responses in drought resistance as it relates to regulation of water uptake and/or loss, while the detected allelic effects demonstrate how maintenance of grain production and yield under drought is a likely result of domestication-derived drought tolerance.

Screening of Inbred Lines of Maize against Turcicum Leaf Blight (Exserohilum turcicum) under Artificial Epiphytotic Conditions

Aims: Turcicum Leaf Blight (TLB), caused by Exserohilum turcicum, significantly affects maize in Karnataka, leading to yield losses of up to 70% in severe cases. To develop tolerant genotypes against this disease, an experiment was conducted using 100 inbred lines collected from the IMIC maize field day in Hyderabad. Study Design: Investigation was carried using Randomized complete block design with two replication. Place and Duration of Study: Maize Research Centre and Seed Farm, Devihosur during kharif-2022. Methodology: One hundred inbred lines were screened against TLB disease. among them 10 resistant lines were selected based on their maturity, disease reaction, grain yield and per se performance. These inbreds along with the checks (Resistant check CI-4 and Susceptible Check CM-202) were sown in Kharif 2022 at Maize Research Centre and Seed Farm Devihosur, UAS, Dharwad. Artificial inoculation was performed 45 days after sowing in the leaf whorls using infected leaves with TLB and the results were evaluated at the silk drying stage. To assess the disease reaction to TLB, we used 1 to 9 scale as established by the Indian Institute of Maize Research, Ludhiana (Anon., 2016). Lines that received disease scores between 1.0 and 3.0 were classified as resistant (R), scores of 4 to 5 as moderately resistant (MR), scores of 6 to 7 as moderately susceptible (MS), and scores of 8 to 9 as susceptible (S). Results: The performance of these lines were compared with the resistant check CI-4 and susceptible check CM-202. Screening trial revealed that out of hundred inbred lines, eighteen lines Showed highly resistant reaction. This information can be useful for selection of parents and to develop tolerant hybrids in breeding programs or utilize them as source of resistance.

Identification of Genetic Loci for Grain Traits and Disease Resistance Reveals a Potential Trade-Off in Rice

Understanding how plants utilize limited resources for reproductivity and disease resistance can improve the efficiency of plant breeding. In the present study, we mapped genes for grain traits, including grain length and width and thousand grain weight (TGW). A previously constructed linkage map of a recombinant inbred line population (MHM) was used, which was derived from a cross between an indica restorer rice variety (Minghui 63) and a temperate japonica rice variety (M-202). The MHM population was grown in replicated field plots, and grain trait data were collected. Upon a 3-year field evaluation, a total of 16 loci were mapped on 9 of 12 chromosomes, including 7 for grain length, 4 for grain weight, and 5 for TGW. A TGW locus ( qTGW2) and a grain width locus ( qWIG2.2) were mapped at the known blast resistance locus qBLAST2 on chromosome 2 that harbors a major blast resistance allele Pi-b. Another TGW locus ( qTGW3.3) and a grain length locus ( qLNG3.3) were mapped at qBLAST3 on chromosome 3. These results reveal potential trade-offs between disease resistance and productivity, which are important for breeders to develop high-yielding and disease-resistant rice varieties. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Additional Advantages for Agronomic Performance and Fruit Quality in Tomato Hybrids of the Saladette Type Derived from a Dwarf Male Parent

Tomatoes have tremendous economic, social, and nutritional importance. Among the various types of tomatoes, the Saladette/Italian stands out as an important cultivar for both fresh consumption and industrial processing. The production of this vegetable requires investments exceeding USD 30,000.00. Strategies that increase productivity to offset these costs are fundamental. One proposal to increase yield potential in tomato is the production of new hybrids using dwarf male parents as donors through an organized backcross breeding scheme. The present study, therefore, evaluated possible improvements in the agronomic performance and fruit quality of Saladette hybrids obtained from crosses between normal and dwarf inbred lines. Seventeen tomato hybrids obtained from three backcrosses (BC1, BC2, and BC3) and two commercial cultivars as a control (cv. Bento and Vivacy) were evaluated. The data were analyzed using the Scott–Knott test, and artificial neural networks were used to study the dissimilarities among the hybrids. The hybrids obtained from the dwarf male parent exhibited morphological changes in the plants, including a reduction in internodes, a greater number of bunches per linear meter of plant, and biofortification of the fruits. Notably, from the second backcross onwards, increases in fruit productivity and quality were observed when creating hybrid combinations from dwarf male parents.

Polymorphic insertions of DcSto miniature inverted-repeat transposable elements reveal genetic diversity structure within the cultivated carrot.

Miniature inverted-repeat transposable elements (MITEs) are a potent source of polymorphisms in plant genomes. A genotyping system, named DcS-ILP, based on polymorphic insertions of Stowaway MITEs (DcStos) localized in introns and identified in the reference genome DH1, has been developed for carrot. Here, we report an extension of the DcS-ILP genotyping system by incorporation of non-reference insertions identified in resequenced genomes representing the eastern gene pool. We genotyped 52 carrot accessions representing the eastern and western carrot gene pools with 92 markers developed previously (western DcS-ILP panel) together with 84 newly developed markers (eastern DcS-ILP panel). Overall, the DcS-ILP markers revealed a highly structured genetic diversity separating the eastern and the western carrot accessions at K = 2 and differentiating Indian breeding lines from the eastern accessions at K = 3. The eastern DcS-ILP panel proved to be more robust with respect to the eastern carrot gene pool, while it provided little information on the western accessions, as many of the DcSto insertions present in the eastern gene pool were absent in the western gene pool. As the western carrot accessions represent improved cultivars, DcSto insertional polymorphisms allowed detection of a selection-driven bottleneck at the improvement stage. Selection in the course of the improvement stage generally operated on standing variation, as the subset of DcSto insertions present in the western carrot likely originated from transposition events preceding the separation of both gene pools. However, occasional frequency shifts in the opposite direction were also revealed, possibly indicating selection for favorable variants associated with DcSto insertions.

QTaHa-5DL: another major QTL regulating wheat grain hardness

Grain hardness has important effects on grain quality and the end-use of wheat. In this study, a collection of 103 common wheat germplasms and a DH population of 194 lines were used to identify new quantitative trait loci (QTL) for grain hardness. Two stable genetic loci on chromosome 5D were detected under different locations and years with one of them being the Ha locus on 5DS where the major gene Puroindolines for wheat grain hardness is located. Another locus of qTaHa-5DL also showed a significant impact on grain hardness index (HI) with HI increasing from ~ 20 to ~ 45 and hardness type changing from soft to mixed when Puroindolines are wild type. A kompetitive allele-specific PCR (KASP) marker for qTaHa-5DL was developed and the effectiveness of the QTL was confirmed in 184 breeding lines with the marker K-Ha5DL dividing wheat into two distinct categories. This new QTL can be effectively used to select soft or medium hard wheat.

HETEROSIS AND GENETIC PARAMETERS FOR YIELD AND YIELD COMPONENTS IN MAIZE USING HALF DIALLEL CROSS

The study was aimed to determine heterosis, GCA, SCA and some genetic parameters in maize (Zea mays L.). Seeds for half diallel crosses among eight inbred lines Planted in spring season 2021 during fall season 2021, the eight parents and 28 hybrids were sowing (10/7/2021) using Randomize Complete Block Design with three replications at the field of College of Agricultural Engineering Sciences, University of Duhok. The results revealed that the mean square for all genotypes was highly significant effects in all studied traits except number of ears per plant. The (Un44052) line was superior in number of rows per ear and grain yield per plant, while the cross (Zp-505 x Un44052) was superior in number ear per plant and number of rows per ear. Six crosses exhibited significant positive heterosis, the crosses Dkc-f-59 x Dk-17, Dkc-f-59 x Un44052, Dkc-f-59 x Zp-430, Zp-505 x Un44052, Zp-607 x Zp-505 and Zp-179 x Un44052. The heritability in broad sense was higher than the heritability narrow sense in studied traits, between 0.33 and 0.97 for number of ear per plant and grain yield per plant. The average degree of dominance was higher than one in studied traits.

Temporally resolved growth patterns reveal novel information about the polygenic nature of complex quantitative traits.

Plant height can be an indicator of plant health across environments and used to identify superior genotypes. Typically plant height is measured at a single timepoint when plants reach terminal height. Evaluating plant height using unoccupied aerial vehicles allows for measurements throughout the growing season, facilitating a better understanding of plant-environment interactions and the genetic basis of this complex trait. To assess variation throughout development, plant height data was collected from planting until terminal height at anthesis (14 flights 2018, 27 in 2019, 12 in 2020, and 11 in 2021) for a panel of ~500 diverse maize inbred lines. The percent variance explained in plant height throughout the season was significantly explained by genotype (9-48%), year (4-52%), and genotype-by-year interactions (14-36%) to varying extents throughout development. Genome-wide association studies revealed 717 significant single nucleotide polymorphisms associated with plant height and growth rate at different parts of the growing season specific to certain phases of vegetative growth. When plant height growth curves were compared to growth curves estimated from canopy cover, greater Fréchet distance stability was observed in plant height growth curves than for canopy cover. This indicated canopy cover may be more useful for understanding environmental modulation of overall plant growth and plant height better for understanding genotypic modulation of overall plant growth. This study demonstrated that substantial information can be gained from high temporal resolution data to understand how plants differentially interact with the environment and can enhance our understanding of the genetic basis of complex polygenic traits.

Uni- and Multivariate Analyses for the Characterization of Popcorn Inbred Lines for Drought Tolerance at Seedling and Vegetative Stages

Water deficit is the main limiting factor in rainfed agricultural production, negatively affecting germination and vegetative development. The objectives of this work were to characterize inbred lines for drought tolerance, to identify the most important root and shoot morphological traits for discriminating genotypes, to compare the efficiency of identifying contrasting inbred lines using uni- and multivariate methods, and to evaluate the effectiveness of identifying drought-tolerant genotypes at seedling and vegetative stages. We assessed 28 popcorn inbred lines and three maize single crosses, two drought-tolerant and one drought-sensitive. At the seedling stage, drought was induced on germitest paper moistened with polyethylene glycol 6000. At the vegetative stage, we applied water stress using lysimeters. We measured root and shoot morphological traits under water stress and no stress and processed the relative values. Uni- and multivariate methods, alone or in combination, were equally efficient for identifying contrasting inbred lines for drought tolerance. The confidence interval and Dunnett’s test worked very well when contrasting controls were included. Principal component analysis allowed to discriminate genotypes and identify the most important traits for discriminating them. At the seedling stage, inbred line 22-1824-2 was the most drought-tolerant and 22-1877-3 the most sensitive. At the vegetative stage, inbred lines 22-1920-1 and 22-1867-4 were the most tolerant and 22-1860-5 was the most sensitive. Root length, volume, dry weight, and surface area, as well as water content, were the most important traits for discriminating genotypes. Due to distinct tolerance mechanisms, drought tolerance should be assessed at both stages.

A single nucleotide substitution introducing premature stop codon within CsTFL1 explains the determinate-2 phenotype in cucumber (Cucumis sativus L.)

The determinate growth habit of plants reduces the number of internodes and shortens the main stem by terminating the shoot apical meristem through a transition to inflorescence. Understanding the genetic basis of this habit can help optimize crop yield and cultivation technology for vegetable breeding. This study aimed to identify the determinate-2 (de-2) gene responsible for the determinate growth habit in the W-sk cucumber line. Termination of the main stem in the W-sk line occurred between 14 and 23 internodes, depending on cultivation conditions. Resequencing of the W-sk genome identified a novel SNP in the cucumber TERMINAL FLOWER1 (CsTFL1) gene, explaining the de-2 phenotype. This was verified with a CAPS-T marker cosegregation with determinate growth in the F2:3 population, and this polymorphism is unique among genotyped indeterminate cucumber cultivars or breeding lines. Crossing the W-sk line with the G421 line with the determinate (de) gene confirmed the allelism of both genes. An SNP in CsTFL1 in the W-sk line introduced a premature stop codon, resulting in the putative deletion of 13 amino acids, possibly causing determinate growth habit. Overall, this study provides insights into the genetic basis of cucumber plant growth architecture and advances in cucumber breeding.

Genetic Diversity and Population Structure Analysis of Soybean [Glycine max (L.) Merrill] Genotypes Using Agro-Morphological Traits and SNP Markers

Background/Objectives: Understanding the genetic diversity of soybean genotypes can provide valuable information that guides parental selection and the design of an effective hybridization strategy in a soybean breeding program. In order to identify genetically diverse, complementary, and prospective parental lines for breeding, this study set out to ascertain the genetic diversity, relationships, and population structure among 35 soybean genotypes based on agro-morphological traits and Single Nucleotide Polymorphic (SNP) marker data. Methods/Results: Cluster analysis, based on agro-morphological traits, grouped the studied genotypes into four clusters. The first two principal components accounted for 62.8% of the total phenotypic variation, where days to 50% flowering, days to 95% maturity, grain yield, shattering score, and lodging score had high and positive contributions to the total variation. Using the SNP marker information, mean values of 0.16, 0.19, 0.067, and 0.227 were obtained for minor allele frequency (MAF), polymorphic information content (PIC), observed heterozygosity (Ho), and expected heterozygosity (He), respectively. Using different clustering approaches (admixture population structure, principal component scatter plot, and hierarchical clustering), the studied genotypes were grouped into four major clusters. Conclusions:The agro-morphological and molecular analysis results indicated the existence of moderate genetic diversity among the studied genotypes. The traits identified to be significantly related to yield provide valuable information for the genetic improvement of soybeans for yield.