Search Results (8)

Background: The regulation of oil and protein contents in cottonseed is governed by a complex genetic network. Gaining insight into the mechanisms controlling these traits is necessary for dissecting the formation patterns of cottonseed quality. Method: In this study, Xinluzhong 37 (P₁) and Xinluzhong 51 (P₂) were selected as parental lines for two reciprocal crosses: P₁ × P₂ (F₁) and its reciprocal P₂ × P₁ (F₁′). Each F1 was selfed and backcrossed to both parents to generate the F₂ (F₂′), B₁ (B₁′), and B₂ (B₂′) generations. To assess nutritional traits in hairy (non-delinted) and lint-free (delinted) seeds, two indicators, oil content and protein content, were measured in both seed types. Joint segregation analysis was employed to analyze the inheritance of these traits, based on a major gene plus polygene model. Results: In the orthogonal crosses, the CVs for the four nutritional traits ranged at 2.710–7.879%, 4.086–11.070%, 2.724–6.727%, and 3.717–9.602%. In the reciprocal crosses, CVs ranged at 2.710–8.053%, 4.086–9.572%, 2.724–6.376%, and 3.717–8.845%. All traits exhibited normal or skewed-normal distributions. For oil content in undelinted/delinted seeds, polygenic heritabilities in the orthogonal cross were 0.64/0.52, and 0.40/0.36 in the reciprocal cross. For protein content, major-gene heritabilities in the orthogonal cross were 0.79 (undelinted) and 0.78 (delinted), while those in the reciprocal cross were both 0.62. Conclusions: Oil and protein contents in cottonseeds are quantitative traits. In both orthogonal and reciprocal crosses, oil content is controlled by multiple genes and is shaped by additive, dominance, and epistatic effects. Protein content, in contrast, is largely controlled by two major genes along with minor genes. In the P₁ × P₂ combination, major genes act through additive, dominance, and epistatic effects, while in the P₂ × P₁ combination, their effects are additive only. In both combinations, minor genes contribute through additive and dominance effects. In summary, the oil content in cottonseed is mainly regulated by polygenes, whereas the protein content is primarily determined by major genes. These genetic features in both linted, and lint-free seeds may offer a theoretical foundation for molecular breeding aimed at improving cottonseed oil and protein quality. Full article

Brassica crops, cultivated as vegetables, oilseeds, and forages, are vital economic resources in agricultural production. However, black rot caused by Xanthomonas campestris pv. campestris (Xcc) poses a significant threat to the production of these crops. This study aimed to enhance the resistance resource pool for Brassica crops by evaluating 29 inbred lines and 52 commercial cultivars of B. rapa through an inoculation test. Among these, 11 inbred lines, such as ‘E5’ and ‘LW’, and 8 commercial cultivars, such as ‘QX’ and ‘SY’, demonstrated high resistance. We constructed a genetic segregating population (P₁, P₂, F₁, F₂) using the highly resistant line ‘E5’ and the highly susceptible line ‘E4’ as parents. Utilizing a major gene plus polygenic mixed inheritance model for genetic analysis, our findings indicate that the resistance to black rot in ‘E5’ is governed by a pair of additive-dominant polygenes, and the main gene heritability is 93.43%. Furthermore, transmission electron microscopy examination revealed numerous autophagic structures in the xylem parenchyma cells of the highly resistant line ‘E5’, while the highly susceptible line exhibited cell necrosis, indicating that the resistant material might protect mesophyll cells and adjacent structures through programmed cell death. This research contributes novel genetic materials for breeding disease-resistant varieties, enhances our understanding of Xcc invasion mechanisms and host defense traits, and establishes a theoretical framework for the effective prevention and control of these diseases. Full article

Plant architecture is a crucial trait for ornamental plants. Chrysanthemum with prostrate growth habit is a novel cultivar group of ground-cover chrysanthemum, which have high ornamental value, strong lodging resistance, and outstanding landscape greening capability. To explore the genetic mechanism underlying the prostrate growth habit in chrysanthemum, we used tetraploid prostrate-type Chrysanthemum yantaiense as the female parent and erect-type Chrysanthemum indicum as the male parent to produce four generations (P₁, P₂, F₁, F₂). Five traits related to prostrate growth habit in chrysanthemum were investigated including plant height (PH), crown width of the plant (CP), creeping index (CI), gravitropic set-point angle (GSA), and growth habit (GH). The major gene plus polygene mixed inheritance analysis was conducted on five traits across four generations over two years. For the five traits, the coefficients of variation (CVs) were wide-ranging and high (16.64–42.75%), with the PH having the highest CV among them. Genetic analysis revealed that PH conformed to the additive-dominant-epistatic polygene model (C-0) and the model of two equally dominant major genes plus additive-dominant polygene (E-5). The most suitable genetic model for CI was an additive-dominant major gene plus additive-dominant-epistatic polygene model (D-0). The best-fit models for CP and GH were both C-0. For GSA, the best-fit models were E-4 and C-0. Additionally, it appeared that both genetic and environmental factors influenced the prostrate growth habit, as the heritability of major genes and polygenes was less than 50%. This study can serve as a theoretical foundation for the mapping of quantitative trait loci (QTLs) and further exploration of the genetic mechanisms underlying plant architecture in chrysanthemum. Full article

Rapeseed (Brassica napus L.) seedlings are rich in vitamin C (Vc), which is beneficial for humans. Understanding the genetic variance in Vc content has practical significance for the breeding of “oil–vegetable dual-purpose” rapeseed. In this study, the joint segregation analysis of a mixed genetic model of the major gene plus polygene was conducted on the Vc content in rapeseed seedlings. Six generations, including two parents, P₁ (high Vc content) and P₂ (low Vc content), F₁, and the populations of F₂, BC₁P1, and BC₁P₂ from two crosses were investigated. Genetic analysis revealed that the genetic model MX2-A-AD was the most fitting genetic model, which indicates that Vc content is controlled by two additive major genes plus additive and dominance polygenes. In addition, the whole heritability in F₂ and BC₁P1 was higher than that in BC₁P2. The largest coefficient of variation for Vc content appeared in the F₂ generation. Therefore, for Vc content, the method of single cross recross or single backcross are suggested to transfer major genes, and the selection in F₂ would be more efficient than that in other generations. Our findings provide a theoretical basis for the quantitative trait locus (QTL) mapping and breeding of Vc content in rapeseed seedlings. Full article

Day-neutral multiflora chrysanthemums can flower throughout the year without being influenced by daylength and have great application value in gardens. Studying heterosis and the genetic basis of important traits in day-neutral chrysanthemums can accelerate the breeding of new cultivars. In this research, a genetic population was constructed by crossing 135 F₁ hybrid progeny from the day-neutral chrysanthemum ‘82-81-19’ (female parent) and the late-flowering chrysanthemum ‘388Q-76’ (male parent). Six traits, including abnormal (crown) bud, plant height, plant crown width, budding date, full flowering date, and number of petal layers, were selected for inheritance and heterosis analyses, and a single-generation major gene plus polygene mixed inheritance model was used to perform mixed inheritance analysis on these traits. The results indicated that the six traits were widely segregated in the F₁ population, with the coefficient of variation (CV) ranging from 30% to 84%. The phenomena of heterosis and extra-parent segregation existed generally in F₁ progeny, and the ratio of heterosis value of mid-parents (RHm) for the six traits was 45.5%, 2%, 2%, 6%, 6%, and −0.3%, respectively. The mixed genetic analysis showed that the abnormal (crown) bud and budding date were fitted to the B-3 model and controlled by two pairs of additive major genes. The plant height and plant crown width were fitted to the A-0 model, and no major gene was detected. The full flowering date was fitted to the A-1 model and was controlled by one pair of major genes. The number of petal layers was fitted to the B-1 model and controlled by two pairs of additive–dominant major genes. The heritabilities of major genes for abnormal bud, budding date, full flowering date, and the number of petal layers were 1.0, 0.9871, 0.7240, and 0.5612, respectively, indicating that these traits were less affected by environmental factors. Using a percentile scoring method, eight day-neutral chrysanthemum genotypes were selected from the hybrid progeny. Full article

Longevity is a complex phenotype influenced by both environmental and genetic factors. The genetic contribution is estimated at about 25%. Despite extensive research efforts, only a few longevity genes have been validated across populations. Long-lived individuals (LLI) reach extreme ages with a relative low prevalence of chronic disability and major age-related diseases (ARDs). We tested whether the protection from ARDs in LLI can partly be attributed to genetic factors by calculating polygenic risk scores (PRSs) for seven common late-life diseases (Alzheimer’s disease (AD), atrial fibrillation (AF), coronary artery disease (CAD), colorectal cancer (CRC), ischemic stroke (ISS), Parkinson’s disease (PD) and type 2 diabetes (T2D)). The examined sample comprised 1351 German LLI (≥94 years, including 643 centenarians) and 4680 German younger controls. For all ARD-PRSs tested, the LLI had significantly lower scores than the younger control individuals (areas under the curve (AUCs): ISS = 0.59, p = 2.84 × 10⁻³⁵; AD = 0.59, p = 3.16 × 10⁻²⁵; AF = 0.57, p = 1.07 × 10⁻¹⁶; CAD = 0.56, p = 1.88 × 10⁻¹²; CRC = 0.52, p = 5.85 × 10⁻³; PD = 0.52, p = 1.91 × 10⁻³; T2D = 0.51, p = 2.61 × 10⁻³). We combined the individual ARD-PRSs into a meta-PRS (AUC = 0.64, p = 6.45 × 10⁻¹⁵). We also generated two genome-wide polygenic scores for longevity, one with and one without the TOMM40/APOE/APOC1 gene region (AUC (incl. TOMM40/APOE/APOC1) = 0.56, p = 1.45 × 10⁻⁵, seven variants; AUC (excl. TOMM40/APOE/APOC1) = 0.55, p = 9.85 × 10⁻³, 10,361 variants). Furthermore, the inclusion of nine markers from the excluded region (not in LD with each other) plus the APOE haplotype into the model raised the AUC from 0.55 to 0.61. Thus, our results highlight the importance of TOMM40/APOE/APOC1 as a longevity hub. Full article

Cabbage (Brassica oleracea var. capitata) Fusarium wilt (CFW) is a disease that poses a critical threat to global cabbage production. Screening for resistant resources in order to support the breeding of resistant cultivars is the most reliable approach to control this disease. CFW is caused by Fusarium oxysporum f. sp. conglutinans (Foc), which consists of two physiological races (race 1 and 2). While many studies have focused on resistance screening, gene mining, and inheritance-based research associated with resistance to Foc race 1, there have been few studies specifically analyzing resistance to Foc race 2, which is a potential threat that can overcome type A resistance. Here, 166 cabbage resources collected from around the world were evaluated for the resistance to both Foc races, with 46.99% and 38.55% of these cabbage lines being resistant to Foc race 1 and race 2, respectively, whereas 33.74% and 48.80% were susceptible to these two respective races. Of these 166 analyzed cabbage lines, 114 (68.67%) were found to be more susceptible to race 2 than to race 1, and 28 of them were resistant to race 1 while susceptible to race 2, underscoring the highly aggressive nature of Foc race 2. To analyze the inheritance of Foc race 2 resistance, segregated populations derived from the resistant parental line ‘Badger Inbred 16’ and the susceptible one ‘01-20’ were analyzed with a major gene plus polygene mixed genetic model. The results of this analysis revealed Foc race 2-specific resistance to be under the control of two pairs of additive-dominant-epistatic major genes plus multiple additive-dominant-epistatic genes (model E). The heritability of these major genes in the BC₁P₁, BC₁P₂, and F₂ generations were 32.14%, 72.80%, and 70.64%, respectively. In summary, these results may aid in future gene mining and breeding of novel CFW-resistant cabbage cultivars. Full article

The fruit diameter (FD), fruit length (FL), fruit peduncle length (FPL), fruit weight (FW) and fruit index (FI, FL/FD) are important quantitative traits in wolfberry fruit, and also one of the most important goals of variety breeding; however, the inheritance of these traits has not been studied to date. In this study, the genetic analysis of these five fruit traits was undertaken for four pairs of F₁ hybrid populations (CI, CII, CIII and CIV) using the major gene and polygene mixed inheritance model. The results showed that the five fruit traits exhibited super-parent segregation in four hybrid combinations, and five traits of progeny with abundant genetic diversity. In CII, CIII and CIV, the mid-parental heterosis ratio (RH_m%) of FD, FL, FPL and FI was greater than 0 with positive heterosis. FD, FL and FI in CI, CII and CIII were controlled by one pair of additive-dominant major genes (A-1). However, in CIV, FD was controlled by two pairs of additive-dominant alleles (B-6) and FL was best fitted to polygenic control (A-0). In addition, it was found that FPL in CI, CIII and CIV was controlled by one or two pairs of additive-dominant major genes (A-1, B-6, B-1), and FW in CIII and CIV was also controlled by one or two pairs of additive-dominant major gene controls (A-1, B-1). For FD, FPL, FW and FI in CIII and FPL and FW in CII, the major genes heritability was over 50%, indicating that these traits are affected by both genes and the environment, and that the selection of these traits should be considered in later generations due to the large effect of environmental factors. Therefore, this study provides a theoretical basis for QTL mapping and early selection of hybrid breeding of Lycium fruits. Full article