IntroductionFennel is a cross-pollinating plant and one of the most important medicinal plants of the Apiaceae family, whose essential oil is widely used in various pharmaceutical, food, and cosmetic ...industries. Fennel originated from the Mediterranean region and is a biennial or perennial species. Fennel essential oil has been demonstrated to have antioxidant, anti-cancer, antibacterial, antifungal, and analgesic effects. Improving yield is one of the important goals of breeding, and the use of heterosis as one of the powerful tools to improve yield has always been of interest to breeders. This study was conducted to evaluate seed yield and yield components of three synthetic cultivars of fennel and compere with eight parental populations.Materials and MethodsTo investigate the yield, yield components, and the degree of heterosis of important traits of breeding fennel cultivars, three synthetic cultivars along with eight superior parents were investigated in the form of a randomized complete block design. The experiment was conducted in the spring of 2019 in the research field of the College of Aburaihan, University of Tehran, located in Pakdasht. During the growing period and after harvest the traits such as no. umbel, number of nodes, no. umbellets per umbel, no. seed per umbel, harvest index, seed yield per plant, plant biomass, 1000 seed weight, essential oil content, essential oil yield, and seed yield were measured in the 50% flowering stage. Analysis of variances was done and a comparison of means was performed by Duncan٬s multiple range at a five percent probability level. Heterosis, Heritability of traits, and some genetic parameters of the traits in fennel genotypes were calculated. To determine the genetic distance and grouping of genotypes, principal component analysis, and cluster analysis were performed. All analyses were carried out using the SAS and Statgraphics software.Results and DiscussionBased on the results of the analysis of variance, the differences between the studied genotypes were significant for all traits. Medium and late synthetic cultivars had significantly higher seed yield and essential oil yield than other genotypes and their yield heterosis rate was positive compared to the average of parents and was 39% and 38%, respectively. Evaluation of heterosis rate showed that cultivars Synthetics were superior to parents in most traits. General heritability for different traits was estimated to be between 34% and 93%. In this study, the phenotypic variation coefficients of all traits were higher than the genetic variation coefficients, which indicated the existence of environmental factors for these traits The results showed that principal components that the first four components account for more than 90% of the total variance changes. Based on the cluster, genotypes were divided into four groups. It could be expected that these synthetic cultivars can be introduced and expanded in the market of medicinal plants after being registered as commercial cultivars.ConclusionIn general, the results of this study indicated that the mean squares of the parents against synthetic cultivars were significant for most of the traits, indicating the occurrence of heterosis in these traits. The results showed that the heterosis of most traits of synthetic cultivars was additive and positive. The highest percentage of heterosis compared to parents was for seed yield, essential oil yield, and the number of umbrellas per plant. It also seems that the traits related to yield components have higher heritability than other traits. The results showed that the synthetic cultivars were superior to their parent genotypes in terms of seed yield and essential oil yield. As a result, it should be said that the breeding method of creating synthetic cultivars in the fennel plant is successful. It can be expected that these synthetic cultivars could be introduced and expanded in the market of medicinal plants after being registered as commercial cultivars.
In the past, rice hybrids with strong heterosis have been obtained empirically, by developing and testing thousands of combinations. Here, we aimed to determine whether heterosis of an elite hybrid ...could be achieved by manipulating major quantitative trait loci. We used 202 chromosome segment substitution lines from the elite hybrid Shanyou 63 to evaluate single segment heterosis (SSH) of yield per plant and identify heterotic loci. All nine detected heterotic loci acted in a dominant fashion, and no SSH exhibited overdominance. Functional alleles of key yield‐related genes Ghd7, Ghd7.1, Hd1, and GS3 were dispersed in both parents. No functional alleles of three investigated genes were expressed at higher levels in the hybrids than in the more desirable parents. A hybrid pyramiding eight heterotic loci in the female parent Zhenshan 97 background had a comparable yield to Shanyou 63 and much higher yield than Zhenshan 97. Five hybrids pyramiding eight or nine heterotic loci in the combined parental genome background showed similar yield performance to that of Shanyou 63. These results suggest that dominance underlying functional complementation is an important contributor to yield heterosis and that heterosis assembly might be successfully promised by manipulating several major dominant heterotic loci.
An analysis that studied heterosis at a single‐locus level in 13 near isogenic F1 hybrids and pyramided heterosis by producing F1 heterozygous at 8 heterosis loci indicated that dominance rather than overdominance contributes to heterosis in rice. Assembling heterosis by manipulating several major QTLs is a promising approach.
La F1 de híbridos Zea perennis (Zp) n=20 x Z. mays (Zm) n=10 está descripta como perenne, de gran vigor, prolífica, con muchos tallos similares a Zp, más vigorosos y altos, con rizomas definidos y ...esterilidad por el comportamiento meiótico (5 mono, 5 bi- y 5 trivalentes). La heterosis para producción de forraje, junto a la esterilidad, delimitaron a la F1 para multiplicación agámica. En este trabajo se describe un nuevo híbrido F1 , genotipo Zpxm114, obtenido en 2014 en Pergamino, con germoplasma de Zp como ♀ y Zm macollador como ♂, evaluado como planta forrajera en Yacanto-San Javier (Córdoba) y Quines (San Luis), para determinar vigor, producción, adaptación, persistencia y manejo agronómico, en suelos con limitantes para Zm o uso agrícola. Macollos de Zpxm114 fueron implantados en 2018 y 2019 y evaluados en 2019/20/21 (cuatro épocas de implantación, tres evaluaciones por año según fenología). Todas las plantas (cuatro épocas en nueve evaluaciones), se adaptaron y produjeron forraje y nuevos macollos (sin heladas severas) y requirieron régimen pluviométrico ≥550 mm o riego suplementario. La heterosis de Zpxm114 se observó en la producción de forraje en encañazón y floración, aun en condiciones limitantes. Produjo 4.450 ± 1.340 kgMSha-1 (promedio general) y 7.700 kg como rendimiento potencial. Acumuló azúcares (CHNE) en tallos estériles y fue fenológicamente de días cortos. El vigor híbrido se expresó también en el número de macollos y altura, con 22 macollos promedio, matas (rizomas definidos) de hasta 50 macollos y 2,25 m de altura, según suelos y agua disponible, con adaptación y persistencia.
El tomate (Solanum lycopersicum L.) es una especie modelo para estudios genéticos, especialmente para caracteres del fruto, y el mejoramiento de los cultivos. Sus frutos juegan un rol importante en ...la nutrición y son considerados un reservorio de compuestos benéficos para la salud. En los programas de mejoramiento genético, la generación de variabilidad es la etapa inicial y fundamental para su éxito. El germoplasma silvestre fue utilizado principalmente como fuente de genes de resistencia para enfermedades y plagas, pero nuestro grupo de trabajo las utiliza para desarrollar nuevos cultivares con características de fruto superiores en términos de vida poscosecha, caracteres organolépticos, y nutricionales. Los cruzamientos y su dirección son otra fuente de variabilidad genética. Nuestros resultados demuestran la posibilidad de obtener híbridos con heterosis y alto contenido de metabolitos relacionados al sabor del tomate y componentes nutricionales. Además, la elección de un cultivar como parental femenino o masculino en un cruzamiento afecta la acumulación de metabolitos o la determinación de caracteres agronómicos en los frutos. Finalmente, la creación de alelos mediante edición génica puede ser útil para la mejora de los cultivos. Hemos demostrado el enorme potencial de la ingeniería cis mediada por CRISPR/Cas en generar variabilidad para el peso del fruto. Durante la ponencia mostraré cómo los genes de especies silvestres, la dirección de los cruzamientos y la edición génica de regiones reguladoras generan variabilidad para características del fruto en tomate.
Se estima que entre un 35 a 70% de las angiospermas son poliploides. La poliploidización es una herramienta potente en el mejoramiento genético; las plantas exhiben características como el incremento ...del rendimiento, heterosis, heterocigosis, restauración de la fertilidad y/o frutos sin semilla. En la poliploidización sexual, se utilizan gametos no-reducidos; la desventaja es que estos gametos son controlados genéticamente y su frecuencia está influenciada por el ambiente, su identificación es difícil y no siempre se encuentran disponibles. En la poliploidización somática se utilizan compuestos como la colchicina; la desventaja es que los compuestos deben entrar en contacto con las células en división y pocas son poliploidizadas. El óxido nitroso (N2O) se utiliza para la inducción de gametos no-reducidos, actúa de manera similar a la colchicina, pero al ser un gas, penetra en todo el tejido cuando es sometido a presión. En este trabajo evaluamos el efecto del N2O en la poliploidización de células somáticas en diferentes cultivos y tejidos: escamas de Lilium L., semillas de Eustoma grandiflorum (Raf.), y semillas y yemas axilares de Tagetes erecta L. Los explantes fueron sometidos a tratamientos con N2O a 5 y 6 atm en una cámara de presión, durante 24, 48 y 72 h. En todos los casos se realizaron conteos cromosómicos en células de raíces de plantas regeneradas después de los tratamientos. Se detectó la presencia de células poliploides en todos los casos, confirmando así la utilidad del óxido nitroso para la inducción de poliploidía en células somáticas.
The utilization of heterosis is a successful strategy in increasing yield for many crops. However, it consumes tremendous manpower to test the combining ability of the parents in fields. Here, we ...applied the genomic-selection (GS) strategy and developed models that significantly increase the predictability of heterosis by introducing the concept of a regional parental genetic-similarity index (PGSI) and reducing dimension in the calculation matrix in a machine-learning approach. Overall, PGSI negatively affected grain yield and several other traits but positively influenced the thousand-seed weight of the hybrids. It was found that the C subgenome of rapeseed had a greater impact on heterosis than the A subgenome. We drew maps with overviews of quantitative-trait loci that were responsible for the heterosis (h-QTLs) of various agronomic traits. Identifications and annotations of genes underlying high impacting h-QTLs were provided. Using models that we elaborated, combining abilities between an Ogu-CMS-pool member and a potential restorer can be simulated in silico, sidestepping laborious work, such as testing crosses in fields. The achievements here provide a case of heterosis prediction in polyploid genomes with relatively large genome sizes.
The genus Ocimum contains 35 aromatic species of annual, perennial, and shrub. Basil essential oil has a pleasant scent that both energizes and purifies the environment. It is consumed worldwide ...because of its anti-oxidant and anti-aging properties. The study aimed to find superior hybrids of the basil that produced high amounts of essential oil of better quality. It estimated heterosis while also combining ability, path, and other genetic parameters. We examined basil's general and special combining abilities and other genetic variables that determine yield, chemical makeup, and economic traits. The mean squares for variances in general and specific combining abilities (GCA and SCA) were significant for all thirteen traits, demonstrating that additive and non-additive genes influence these attributes. The hybrid L1 × T3 produced the highest essential oil (6.39 ml/plant), followed by L2 × T1 and L3 × T1 (5.13 ml/plant). The hybrid L1 × T2 and L5 × T1, with the most considerable SCA effect, produced better performances for the (-) linalool content (71.61% and 61.67%). The narrow-sense heritability for the eight characteristics under investigation ranged from 0.0038% to 62.95%. Narrow-sense heritability was moderate in terms of plant height and herb yields. It was high for branches/plant, essential oil yield, and camphor content (%). The genetic advance was also high in most characters, except for three traits: medium inflorescence length, and Chavibetol concentration. We investigated correlations between traits and contributions of the characters toward essential oil yield, as well as differential heterosis in hybrids for the stated variables, to gain a clear picture of the genetic advancement of the basil crop. With the exception of two traits—days to flowering and essential oil—the amplitude of SCA was greater than GCA variance, demonstrating the preponderance of non-additive gene action in the basil. The hybrids L1 × T1 followed by L1 × T3 and L2 × T1 were best for the essential oil yield of better quality. The L × T design is utilized for the first time and described in the Ocimum. These improved hybrids could be beneficial to large-scale farming.
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•The L-T design is utilized for the first time and described in the Ocimum.•Non-additive genes were more important in most of traits than the additive genes.•Days to flowering and the essential oil, expressing the predominance of non-additive gene action.•The heterosis and transgressive breeding approach were suggested for further improvement.•The hybrids L1 × T1, L1 × T3, and L2 ×T1 were best for the essential oil yield of better quality.
Crossbreeding capitalizes on heterosis effects and results in increased performance of crossbred animals. Dominance hypothesis and overdominance hypothesis are 2 common models proposed to explain ...heterosis. Differential gene expression between parents and hybrids is hypothesized to be responsible for heterosis. This study aimed to investigate the heat tolerance and inheritance patterns of leukocyte transcriptomics in F1 hybrid cattle (Angus males × Droughtmaster females) and their parents Red Angus (AN) and Droughtmaster (DR) under heat stress. According to the respiratory rate and heat tolerance coefficient index, DR was better adapted to heat stress than AN. The physiological responses to heat stress of F1 hybrids were similar to AN. We identified 802 differentially expressed genes in leukocytes between AN and DR under heat stress using mRNA sequencing. Compared with AN, upregulated genes in DR were enriched in biological processes of response to stress, external and chemical stimulus, and cytokine, cell surface receptor signaling pathway, and cardiovascular system development. In contrast, upregulated genes in AN were enriched in B cell activation and regulation of B cell activation. Gene expression levels can be inherited additively or nonadditively and are classified into additive (35%), dominance (44%), and overdominance and underdominance (18%) modes in F1 hybrids and their parents. Inheritance patterns of gene expression showed that 97% (249/255) of the dominant genes were classified as paternal AN dominant in hybrids. The paternal imprinted PEG10 gene and its regulatory transcription factor MYC showed an AN dominant expression pattern. The MYC interacted with most AN dominant genes. These transcriptomic analyses revealed that DR and AN had specific cellular and humoral immunity and cardiovascular systems development function under heat stress. Inheritance pattern analyses from gene expression partly explained phenotypic differences between parents and F1 hybrids. The paternal imprinted PEG10 gene interaction with transcription factor MYC may contribute to explaining paternal dominant gene expression in hybrids.
La heterosis, el beneficio fenotípico de los híbridos respecto de sus progenitores puros, fue observada hace más de tres siglos. Sin embargo, su fundamento teórico surge a principios del siglo XX y ...contempla tres hipótesis: dominancia, sobredominancia y epistasis. Esta discusión continúa y las herramientas genómicas están brindando nueva información. En sus comienzos la heterosis era concebida en términos mendelianos, asumiendo un número reducido de genes actuando bajo alguna de las hipótesis antedichas. Posteriormente, con el desarrollo de la genética cuantitativa y en particular en animales, surgió una concepción teórica diferente. Bajo una lógica estadística, el fenotipo (resultado de la acción multigénica) es particionado en diferentes fuentes de información: efectos ambientales y efectos genéticos aditivos, de dominancia y de interacción. En las décadas de 1970 y 1980 se desarrollaron varias parametrizaciones en las que el fenotipo promedio de cada tipo de cruzamiento (F1 , F2, cruzas recíprocas, etc.) nos brinda información para la estimación de los efectos de heterosis. Todas ellas se fundan en el conocimiento de la composición (S) y heterocigosis (H) racial que, como las relaciones entre individuos, eran estimadas por pedigree. En la nueva era genómica es posible refinar las relaciones genéticas entre dos individuos y obtener un valor que difiere del estimado por pedigree; del mismo modo en animales cruza, es posible estimar Si y Hi , parámetros que previamente eran estimados a partir del pedigree. Esta exposición desarrollará los conceptos antes descriptos y mostrará cómo explotar la información genómica bajo este enfoque cuantitativo en animales cruza (o individuos híbridos diploides). Finalmente, se presentarán algunas experiencias utilizando la información genómica de animales cruza para la estimación de la composición y heterocigosis racial, detección de huellas de selección, estimación de los efectos de heterosis y su origen.
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