Heterosis and Combining Ability for Fruit Yield, Sweetness, β-Carotene, Ascorbic Acid, Firmness and Fusarium Wilt Resistance in Muskmelon (Cucumis melo L.) Involving Genetic Male Sterile Lines

Ten genetically diverse inbred lines, including two genic male sterile lines, of muskmelon (Cucumis melo L.) were crossed in a half-diallel to generate 45 F1 hybrids. These hybrids, along with the parental lines and commercial check, were evaluated for their fruit yield, level of phytochemicals and Fusarium wilt resistance. Both additive and non-additive genetic variances were important in governing the expression of all of the traits; however, the additive gene action for the fruit weight (g), flesh thickness (cm), rind thickness (mm), firmness (lb inch−2), β-carotene content (mg/100 g), non-additive variance for fruit yield (t ha−1), fruit number, total soluble solids (TSS, °Brix), ascorbic acid (mg/100 g) and reaction to Fusarium wilt were comparatively more important. The parental line MM-625 was the best general combiner for fruit yield, rind thickness and β-carotene content (mg/100 g). The exotic line Riogold was the best combiner for flesh thickness and firmness. The netted inbred line MM-610 was the best general combiner for fruit weight, ascorbic acid and reaction to Fusarium wilt. The inbred lines KP4HM-15 and MM-916 were the best general combiners for the number of fruits per vine and TSS. The best cross-combinations for fruit yield ha−1 and TSS were MS-1×M-610 and Kajri×MM-904, respectively. The hybrids KP4HM-15×MM Sel-103 and KP4HM-15×MM-1831 recorded the highest standard heterosis for fruit yield and TSS. The landrace-derived inbred lines Kajri, MM Sel-103 and KP4HM-15 produced moderate-to-highly FW-resistant hybrids. Out of the 121 SSR markers applied, 70 exhibited parental polymorphism. The markers DM0561, CMAAAGN14, TJ147, CMMS35_3, CMAGN45 and DE1337 identified specific/unique alleles in certain parental genotypes. Thus, the findings of this study revealed that the novel inbred lines can effectively be combined to generate heterotic F1 hybrids for yield and other traits, such as rind and flesh thickness, TSS, β-carotene content and firmness. Furthermore, SSR markers can potentially be utilized to confirm the genetic diversity among the parental lines, and for the DNA fingerprinting of F1 hybrids.

Assessment of the relationship of yield and its contributing traits in wheat

Wheat is an essential source of nutrition for humans and an important cereal crop of Pakistan due to its widespread use as food. To fulfill the nutrition needs of boosted population, crop yield must be improved. In this perspective, we conducted the experiment reported in this paper to achieve correlation and path coefficient attributes given by yield-related traits. Our study enables to understand the association and contribution of nine traits toward grain production. The genetic material was comprised of seven parents and twelve F1 hybrids. Correlation analysis showed that grain yield per spike, thousand grain weight, spike length, and number of tillers per plant have positive and significant correlation with grain yield per plant, at both genotypic and phenotypic level. Path coefficient analysis revealed that direct effects of number of tillers per plant, grain yield per spike, and spike length were positive. This data persuaded that selection based on these traits could be useful for breeding purposes to higher grain yield.

Optimization of the Androgenesis Method in the In Vitro Culture of Anteneson the Basis ofT. AestivumHybrids

This study aimed to examine the regularities of the regenerationprocesses of haploid plants, the dependence of in vitro microspore morphogenesis in anther culture on optimization factors, and their efficiency in F1 hybrids of T. aestivumof different ecological and geographicorigin. It was found that heterosis contributed to an increased yield of haploid chlorophyll-bearing regenerants from hybrids obtained from the crossing of parental forms with different responsiveness to androclinia. Results were obtained for the complex optimization of the androgenesis method for the in vitro anther culture of T. aestivum, in order to create diploidized haploid lines (DHL) regardless of the influence of the genotype. The agroecological properties for a complex of economically useful traits were also assessed. DHLs were created that combined high yield (5.1-6.8 t / ha) with lodging resistance (straw height – 60-80 cm) and consistently high grain quality; these were characterized by increased resistance to major leaf diseases in comparison with the standard variety in the conditions of the Central Economic Region of the Non-Black Earth Zone of the Russian Federation. Keywords: spring soft wheat, androgenesis, embyroidogenesis, callusogenesis, diploidized haploids, in vitro, yield and quality

Environment-Dependent Heterosis and Transgressive Gene Expression in Reciprocal Hybrids between the Channel Catfish Ictalurus punctatus and the Blue Catfish Ictalurus furcatus

The hybrid between female channel catfish (Ictalurus punctatus) and male blue catfish (Ictalurus furcatus) is superior in feed conversion, disease resistance, carcass yield, and harvestability compared to both parental species. However, heterosis and heterobeltiosis only occur in pond culture, and channel catfish grow much faster than the other genetic types in small culture units. This environment-dependent heterosis is intriguing, but the underlying genetic mechanisms are not well understood. In this study, phenotypic characterization and transcriptomic analyses were performed in the channel catfish, blue catfish, and their reciprocal F1s reared in tanks. The results showed that the channel catfish is superior in growth-related morphometrics, presumably due to significantly lower innate immune function, as investigated by reduced lysozyme activity and alternative complement activity. RNA-seq analysis revealed that genes involved in fatty acid metabolism/transport are significantly upregulated in channel catfish compared to blue catfish and hybrids, which also contributes to the growth phenotype. Interestingly, hybrids have a 40–80% elevation in blood glucose than the parental species, which can be explained by a phenomenon called transgressive expression (overexpression/underexpression in F1s than the parental species). A total of 1140 transgressive genes were identified in F1 hybrids, indicating that 8.5% of the transcriptome displayed transgressive expression. Transgressive genes upregulated in F1s are enriched for glycan degradation function, directly related to the increase in blood glucose level. This study is the first to explore molecular mechanisms of environment-dependent heterosis/heterobeltiosis in a vertebrate species and sheds light on the regulation and evolution of heterosis vs. hybrid incompatibility.

Phosphate transporter PHT1;1 as a key determinant of phosphorus acquisition in Arabidopsis natural accessions

To understand the genetic basis in governing phosphorus (P) acquisition, we performed genome-wide association studies (GWAS) on a diversity panel of Arabidopsis thaliana by two primary determinants of P acquisition, phosphate (Pi)-uptake activity and PHOSPHATE TRANSPORTER 1 (PHT1) protein abundance. Association mapping revealed a shared significant peak on chromosome 5 (Chr5) where the PHT1;1/2/3 genes reside, suggesting a strong correlation between the regulation of Pi-uptake activity and PHT1 protein abundance. Genes encoding transcription factors, kinases, and a metalloprotease associated with both traits were also identified. Conditional GWAS followed by statistical analysis of genotype-dependent expression of PHT1;1 and transcription activity assays revealed an epistatic interaction between PHT1;1 and MYB DOMAIN PROTEIN 52 (MYB52) on Chr1. Analyses of F1 hybrids generated by crossing two subgroups of natural accessions carrying specific SNPs associated with PHT1;1 and MYB52 further revealed the strong effects of potential variants on PHT1;1 expression and Pi uptake activity. Notably, the soil P contents in A. thaliana habitats were found to coincide with PHT1;1 haplotype, underscoring how fine-tuning of the activity of P acquisition by natural variants allows plants to adapt to their environments. This study sheds light on the complex regulation of P acquisition and offers a framework to systematically assess the effectiveness of GWAS approaches in the study of quantitative traits.

Heterotic groups for identifying of suitable combiners in sunflower using top-cross

The study was conducted in order to identify the suitable parental inbred lines using top cross method for improvement of new sunflower F1 single cross hybrids at research field of Seed and Plant Improvement Institute in Karaj, Iran during two Crop season (2018 and 2019). Experimental materials consisted of 31 restore lines and 43 cytoplasmic male sterile lines which were crossed with A1221 and R14 as the testers respectively. The developed F1 hybrids were evaluated for GCA of three breeding objectives i.e. flowering time, plant height and grain yield during two years replicated trials. Cluster analysis revealed two heterotic groups in which the restorer lines; R22, R24 and R38 (Grain yield of 33, 32 and 31 g head-1 respectively) and three CMS lines; A32, A370 and A110 (Grain yield of 47, 44 and 43 g head-1 respectively) were identified as the suitable restorer and cytoplasmic male sterile line for improvement of new sunflower single cross hybrids. Evaluation of specific combing ability of the resulted combinations will reveal the efficiency of this selection in the following generation.

Identification of Cotton F1 Hybrids and their Parents through Molecular Marker under Salinity Stress

An experiment was carried out at Main Cotton Research Station, NAU, Surat, Gujarat, India during 2018–2020 to identify F1 hybrids and their parents through SSR marker for salinity tolerance in cotton. The four cotton parents (two salt tolerant and two salt sensitive) were crossed in a diallel fashion to obtain twelve cotton hybrids and subjected to DNA isolation and PCR amplification with SSR markers. In the present study, six SSR markers (TMB0409, DPL0094, BNL686, JESPR153, CM45 and MGHES006) were identified to be polymorphic between parents and the hybrids. The SSR primer TMB0409, DPL0094, JESPR153 and CM45 identified two fragments each from different parents in two, two, four and eight cotton hybrids, respectively, which confirmed true hybrids. Hence, the SSR molecular marker, individually or in combination can be used to distinguish and confirm the hybrid and parents in cotton with special reference to salinity. The PCA analysis revealed that BNL686–1 (248 bp) allele contributed significantly to the quantum of variation as explained by PC1. Hence, this allele is able to serve as a benchmark for ascertaining the efficient pattern of grouping between genotypes. Further, the marker CM45 amplified a fragment specific to the saline tolerant parents which was absent in sensitive parents as well as a fragment produced in sensitive parent which was absent in the tolerant parents, hence the molecular marker CM45 may associate with the salinity tolerance in cotton and can be used for salinity tolerant breeding program after confirming in a large population.

Simultaneous Selection of Sweet-Waxy Corn Ideotypes Appealing to Hybrid Seed Producers, Growers, and Consumers in Thailand

Multi-trait selection helps breeders identify genotypes that appeal to divergent groups of preferences. In this study, we performed simultaneous selection of sweet-waxy corn hybrids on several traits covering the perspectives of consumers (taller kernel depth, better eating quality), growers (early maturity, shorter plant stature, and high ear yield), and seed producers (high flowering synchrony, acceptable seed yield, and good plant architecture). Three supersweet corn lines and 8 waxy corn lines were intercrossed to generate 48 F1 hybrids according to North Carolina Design II, and these genotypes were laid out in a randomized complete block design with 3 replications across 2 seasons between 2017 and 2018. A sensory blind test on sweetness, stickiness, tenderness, and overall liking was conducted to assess the eating quality of steamed corn samples. Two methods of simultaneous selection, namely unweighted selection index and overall rank-sum index (ORSI), were applied to rank crosses, following all targeted groups of preferences. Genetic parameters and genetic gain were estimated to evaluate the effectiveness of those selection methods. Both approaches had similar patterns of preferable realized gain on each given trait and could identify similar top five crosses with only slight order changes, implying that these methods were effective to rank genotypes according to given selection criteria. One of the tested crosses, 101L/TSC-10 × KV/mon, consistently had the highest unweighted selection index in the dry (7.84) and the rainy (7.15) seasons and the lowest ORSI (310), becoming a promising candidate as synergistic sweet-waxy corn hybrid appealing to consumers, growers, and seed producers. The expected ideotypes of sweet-waxy corn hybrid are discussed.

Identification of Accession-Specific Variants and Development of KASP Markers for Assessing the Genetic Makeup of Crop Seeds

Background Most crop seeds are F1 hybrids. Seed providers and plant breeders must be confident that the seed supplied to growers is of known, and uniform, genetic makeup. This requires maintenance of pure genotypes of the parental lines and testing to ensure the genetic purity of the F1 seed. Traditionally, seed testing for purity was done with a grow-out test (GOT) in the field, but these tests are time consuming and costly. Seed testing with molecular markers was introduced as a replacement for GOT early in the last decade. Recently, Kompetitive allele specific PCR (KASP) markers are promising tools for genetic testing of seeds. However, the markers available at that time could be inaccurate and could be used with only a small number of accessions or varieties due to the limited genetic information and reference genomes available. Results Here, we identified 4,925,742 SNPs in 50 accessions of the Brasscia rapa core collection. Furthermore, the total 2,925 SNPs were selected as accession-specific SNPs, considering properties of flanking region harboring accession-specific SNPs and genic region conservation among accessions by NGS analysis. In total, 100 accession-specific markers were developed as accession-specific KASP markers. Based on the results of our validation experiments, the accession-specific markers successfully distinguish individuals from the mixed population including 50 target accessions from B. rapa core collection and outgroup. Conclusions This study provides efficient methods for developing KASP markers to distinguish individuals from the mixture comprised of breeding lines and germplasms from the resequencing data of Chinese cabbage (Brassica rapa spp. pekinensis).