The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Nathan M Springer - One of the best experts on this subject based on the ideXlab platform.
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genotype by environment interactions affecting Heterosis in maize
PLOS ONE, 2018Co-Authors: Zhi Li, Patrick S Schnable, Shawn M Kaeppler, Lisa Coffey, Jacob Garfin, Nathan D Miller, Michael R White, Edgar P Spalding, Natalia De Leon, Nathan M SpringerAbstract:The environment can influence Heterosis, the phenomena in which the offspring of two inbred parents exhibits phenotypic performance beyond the inbred parents for specific traits. In this study we measured 25 traits in a set of 47 maize hybrids and their inbred parents grown in 16 different environments with varying levels of average productivity. By quantifying 25 vegetative and reproductive traits across the life cycle we were able to analyze interactions between the environment and multiple distinct instances of Heterosis. The magnitude and rank among hybrids for better-parent Heterosis (BPH) varied for the different traits and environments. Across the traits, a higher within plot variance was observed for inbred lines compared to hybrids. However, for most traits, variance across environments was not significantly different for inbred lines compared to hybrids. Further, for many traits the correlations of BPH to hybrid performance and BPH to better parent performance were of comparable magnitude. These results indicate that inbred lines and hybrids show similar trends in environmental response and both are contributing to observed genotype-by-environment interactions for Heterosis. This study highlights the degree of Heterosis is not an inherent trait of a specific hybrid, but varies depending on the trait measured and the environment where that trait is measured. Studies that attempt to correlate molecular processes with Heterosis are hindered by the fact that Heterosis is not a consistent attribute of a specific hybrid.
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genotype by environment interactions affecting Heterosis in maize
bioRxiv, 2017Co-Authors: Zhi Li, Patrick S Schnable, Shawn M Kaeppler, Lisa Coffey, Jacob Garfin, Nathan D Miller, Michael R White, Edgar P Spalding, Natalia De Leon, Nathan M SpringerAbstract:The environment can influence Heterosis, the phenomena in which the offspring of two inbred parents exhibits phenotypic performance beyond the inbred parents for specific traits. In this study we measured 25 traits in a set of 47 maize hybrids and their inbred parents grown in 16 different environments, and each had varying levels of average productivity. By quantifying 25 vegetative and reproductive traits across the life cycle we were able to analyze interactions between the environment and multiple distinct instances of Heterosis. The magnitude and rank among hybrids of better-parent Heterosis (BPH) varied for the different traits and environments. Across the traits, a higher within plot variance was observed for inbred lines compared to hybrids. However, for most traits, variance across environments was not significantly different for inbred lines compared to hybrids. Further, for many traits the correlations of BPH to hybrid performance and BPH to better parent performance were of comparable magnitude. These results indicate that inbreds and hybrids are showing similar trends in environmental response and are both contribute to genotype-by-environment interactions for Heterosis. This study highlights that degree of Heterosis is not an inherent trait of a specific hybrid, but varies depending on the trait measured and the environment where that trait is measured. Studies that attempt to correlate molecular processes with Heterosis are hindered by the fact that Heterosis is not a consistent attribute of a specific hybrid.
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progress toward understanding Heterosis in crop plants
Annual Review of Plant Biology, 2013Co-Authors: Patrick S Schnable, Nathan M SpringerAbstract:Although Heterosis, or hybrid vigor, is widely exploited in agriculture, a complete description of its molecular underpinnings has remained elusive despite extensive investigation. It appears that there is not a single, simple explanation for Heterosis. Instead, it is likely that Heterosis arises in crosses between genetically distinct individuals as a result of a diversity of mechanisms. Heterosis generally results from the action of multiple loci, and different loci affect Heterosis for different traits and in different hybrids. Hence, multigene models are likely to prove most informative for understanding Heterosis. Complementation of allelic variation, as well as complementation of variation in gene content and gene expression patterns, is likely to be an important contributor to Heterosis. Epigenetic variation has the potential to interact in hybrid genotypes via novel mechanisms. Several other intriguing hypotheses are also under investigation. In crops, Heterosis must be considered within the conte...
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Heterosis is prevalent for multiple traits in diverse maize germplasm
PLOS ONE, 2009Co-Authors: Sherry Flintgarcia, Edward S Buckler, Peter Tiffin, Elhan S Ersoz, Nathan M SpringerAbstract:Background: Heterosis describes the superior phenotypes observed in hybrids relative to their inbred parents. Maize is a model system for studying Heterosis due to the high levels of yield Heterosis and commercial use of hybrids. Methods: The inbred lines from an association mapping panel were crossed to a common inbred line, B73, to generate nearly 300 hybrid genotypes. Heterosis was evaluated for seventeen phenotypic traits in multiple environments. The majority of hybrids exhibit better-parent Heterosis in most of the hybrids measured. Correlations between the levels of Heterosis for different traits were generally weak, suggesting that the genetic basis of Heterosis is trait-dependent. Conclusions: The ability to predict Heterosis levels using inbred phenotype or genetic distance between the parents varied for the different traits. For some traits it is possible to explain a significant proportion of the Heterosis variation using linear modeling while other traits are more difficult to predict.
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gene expression analyses in maize inbreds and hybrids with varying levels of Heterosis
BMC Plant Biology, 2008Co-Authors: Robert M Stupar, Jack M Gardiner, Aaron Oldre, William J Haun, Vicki L Chandler, Nathan M SpringerAbstract:Background Heterosis is the superior performance of F1 hybrid progeny relative to the parental phenotypes. Maize exhibits Heterosis for a wide range of traits, however the magnitude of Heterosis is highly variable depending on the choice of parents and the trait(s) measured. We have used expression profiling to determine whether the level, or types, of non-additive gene expression vary in maize hybrids with different levels of genetic diversity or Heterosis.
Qifa Zhang - One of the best experts on this subject based on the ideXlab platform.
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genetic composition of yield Heterosis in an elite rice hybrid
Proceedings of the National Academy of Sciences of the United States of America, 2012Co-Authors: Gang Zhou, Ying Chen, Chengjun Zhang, Yongzhong Xing, Jinghua Xiao, Qifa ZhangAbstract:Heterosis refers to the superior performance of hybrids relative to the parents. Utilization of Heterosis has contributed tremendously to the increased productivity in many crops for decades. Although there have been a range of studies on various aspects of Heterosis, the key to understanding the biological mechanisms of heterotic performance in crop hybrids is the genetic basis, much of which is still uncharacterized. In this study, we dissected the genetic composition of yield and yield component traits using data of replicated field trials of an “immortalized F2” population derived from an elite rice hybrid. On the basis of an ultrahigh-density SNP bin map constructed with population sequencing, we calculated single-locus and epistatic genetic effects in the whole genome and identified components pertaining to Heterosis of the hybrid. The results showed that the relative contributions of the genetic components varied with traits. Overdominance/pseudo-overdominance is the most important contributor to Heterosis of yield, number of grains per panicle, and grain weight. Dominance × dominance interaction is important for Heterosis of tillers per plant and grain weight and has roles in yield and grain number. Single-locus dominance has relatively small contributions in all of the traits. The results suggest that cumulative effects of these components may adequately explain the genetic basis of Heterosis in the hybrid.
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Heterosis and polymorphisms of gene expression in an elite rice hybrid as revealed by a microarray analysis of 9198 unique ests
Plant Molecular Biology, 2006Co-Authors: Yi Huang, Lida Zhang, Jianwei Zhang, Dejun Yuan, Caiguo Xu, Xianghua Li, Daoxiu Zhou, Shiping Wang, Qifa ZhangAbstract:Despite the significant contributions of utilizing Heterosis to crop productivity worldwide, the biological mechanisms of Heterosis remained largely uncharacterized. In this study, we analyzed gene expression profiles of an elite rice hybrid and the parents at three stages of young panicle development, using a cDNA microarray consisting of 9198 expressed sequence tags (ESTs), with the objective to reveal patterns of gene expression that may be associated with Heterosis in yield. A total of 8422 sequences showed hybridization signals in all three genotypes in at least one stage and 5771 sequences produced detectable signals in all slides. Significant differences in expression level were detected for 438 sequences among the three genotypes in at least one of the three stages, as determined by ANOVA validated with 100 permutations at P < 0.05. Significant mid-parent Heterosis was detected for 141 sequences, which demonstrated the following features: a much larger number of sequences showed negative Heterosis than ones showing positive Heterosis; genes functioning in DNA replication and repair tended to show positive Heterosis; genes functioning in carbohydrate metabolism, lipid metabolism, energy metabolism, translation, protein degradation, and cellular information processing showed negative Heterosis; both positive and negative Heterosis were observed for genes in amino acid metabolism, transcription, signal transduction, plant defense and transportation. The results are indicative of the biochemical and physiological activities taking place in the hybrid relative to the parents. Identification of genes showing expression polymorphisms among different genotypes and heterotic expression in the hybrid may provide new avenues for exploring the biological mechanisms underlying Heterosis.
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single locus heterotic effects and dominance by dominance interactions can adequately explain the genetic basis of Heterosis in an elite rice hybrid
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Yongzhong Xing, Caiguo Xu, Weiren Wu, Sibin Yu, Qifa ZhangAbstract:The genetic basis of Heterosis of an elite rice hybrid was investigated by using an “immortalized F2” population produced by randomly permutated intermating of 240 recombinant inbred lines from a cross between the parents of Shanyou 63, the most widely cultivated hybrid in China. Measurements of Heterosis for crosses in the immortalized F2 population were obtained from replicated field trials over 2 years by inter-planting the hybrids with the parental recombinant inbred lines. The analyses were conducted making use of a linkage map comprising 231 segregating molecular marker loci covering the entire rice genome. Heterotic effects were detected at 33 loci for the four traits with modified composite interval mapping. The heterotic loci showed little overlap with quantitative trait loci for trait performance, suggesting that Heterosis and trait performance may be conditioned by different sets of loci. Large numbers of digenic interactions were resolved by using two-way ANOVA and confirmed by randomization tests. All kinds of genetic effects, including partial-, full-, and overdominance at single-locus level and all three forms of digenic interactions (additive by additive, additive by dominance, and dominance by dominance), contributed to Heterosis in the immortalized F2 population, indicating that these genetic components were not mutually exclusive in the genetic basis of Heterosis. Heterotic effects at the single-locus level, in combination with the marginal advantages of double heterozygotes caused by dominance by dominance interaction at the two-locus level could adequately explain the genetic basis of Heterosis in Shanyou 63. These results may help reconcile the century-long debate concerning the genetic basis of Heterosis.
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a diallel analysis of Heterosis in elite hybrid rice based on rflps and microsatellites
Theoretical and Applied Genetics, 1994Co-Authors: Qifa Zhang, S H Yang, R A Ragab, M Saghai A Maroof, Zaiyun LiAbstract:Hybrid rice has contributed significantly to the dramatic increase of rice production in the world. Despite this, little attention has been given to studying the genetic basis of Heterosis in rice. In this paper, we report a diallel analysis of Heterosis using two classes of molecular markers: restriction fragment length polymorphisms, (RFLPs) and microsatellites. Eight lines, which represent a significant portion of hybrid rice germ plasm, were crossed in all possible pairs, and the F1s were evaluated for yield and yield component traits in a replicated field trial. The parental lines were surveyed for polymorphisms with 117 RFLP probes and ten microsatellites, resulting in a total of 76 polymorphic markers well-spaced in the rice RFLP map. The results indicated that high level Heterosis is common among these crosses: more than 100% midparent and 40% better-parent Heterosis were observed in many F1s, including some crosses between maintainer lines. Heterosis was found to be much higher for yield than for yield component traits, which fits a multiplicative model almost perfectly. Between 16 and 30 marker loci (positive markers) detected highly significant effects on yield or its component traits. Heterozygosity was significantly correlated with several attributes of performance and Heterosis. Correlations based on positive markers (specific heterozygosity) were large for midparent Heterosis of yield and seeds/panicle and also for F1 kernel weight. These large correlations may have practical utility for predicting Heterosis.
Dirk K Hincha - One of the best experts on this subject based on the ideXlab platform.
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predicting arabidopsis freezing tolerance and Heterosis in freezing tolerance from metabolite composition
Molecular Plant, 2010Co-Authors: Marina Korn, Tanja Gartner, Joachim Selbig, Alexander Erban, Joachim Kopka, Dirk K HinchaAbstract:Heterosis, or hybrid vigor, is one of the most important tools in plant breeding and has previously been demonstrated for plant freezing tolerance. Freezing tolerance is an important trait because it can limit the geographical distribution of plants and their agricultural yield. Plants from temperate climates increase in freezing tolerance during exposure to low, non-freezing temperatures in a process termed ‘cold acclimation’. Metabolite profiling has indicated a major reprogramming of plant metabolism in the cold, but it has remained unclear in previous studies which of these changes are related to freezing tolerance. In the present study, we have used metabolic profiling to discover combinations of metabolites that predict freezing tolerance and its Heterosis in Arabidopsis thaliana. We identified compatible solutes and, in particular, the pathway leading to raffinose as crucial statistical predictors for freezing tolerance and its Heterosis, while some TCA cycle intermediates contribute only to predicting the heterotic phenotype. This indicates coordinate links between Heterosis and metabolic pathways, suggesting that a limited number of regulatory genes may determine the extent of Heterosis in this complex trait. In addition, several unidentified metabolites strongly contributed to the prediction of both freezing tolerance and its Heterosis and we present an exemplary analysis of one of these, identifying it as a hexose conjugate.
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Heterosis in the freezing tolerance and sugar and flavonoid contents of crosses between arabidopsis thaliana accessions of widely varying freezing tolerance
Plant Cell and Environment, 2008Co-Authors: Marina Korn, Arnd G Heyer, Silke Peterek, Hans-peter Mock, Dirk K HinchaAbstract:Heterosis is defined as the increased vigour of hybrids in comparison to their parents. We investigated 24 F 1 hybrid lines of Arabidopsis thaliana generated by reciprocally crossing either C24 or Col with six other parental accessions (Can, Co, Cvi, Ler, Rsch, Te) that differ widely in their freezing tolerance. The crosses differed in the degree of Heterosis for freezing tolerance, both in the non-acclimated state and after a 14 d cold acclimation period. Crosses with C24 showed more Heterosis than crosses with Col, and Heterosis was stronger in acclimated than in non-acclimated plants. Leaf content of soluble sugars and proline showed more deviation from mid-parent values in crosses involving C24 than in those involving Col, and deviations were larger in acclimated than in non-acclimated plants. There were significant correlations between the content of different sugars and leaf freezing tolerance, as well as between Heterosis effects in freezing tolerance and sugar content. Flavonoid content and composition varied between accessions, and between non-acclimated and acclimated plants. In the crosses, large deviations from the mid-parent values in the contents of different flavonols occurred, and there were strikingly strong correlations between both flavonol content and freezing tolerance, and between Heterosis effects in freezing tolerance and flavonol content.
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Heterosis in the freezing tolerance of crosses between two arabidopsis thaliana accessions columbia 0 and c24 that show differences in non acclimated and acclimated freezing tolerance
Plant Journal, 2004Co-Authors: Peter P Rohde, Dirk K Hincha, Arnd G HeyerAbstract:Heterosis is broadly defined as the increased vigour of hybrids in comparison to their parents. In the model plant Arabidopsis thaliana, a significant Heterosis effect on leaf-freezing tolerance was observed in the F(1) generation of a cross between the accessions Columbia-0 (Col) and C24. Parental Col plants were significantly more freezing-tolerant than C24 plants in both the acclimated and non-acclimated (NA) states. Mid-parent Heterosis was observed in the F(1) plants, both in the basic tolerance of non-adapted plants and in freezing tolerance after cold acclimation. Best-parent Heterosis, on the other hand, was only found after cold acclimation. The Heterosis effect was reduced in the F(2) populations such that only mid-parent Heterosis was evident. The leaf content of soluble sugars (fructose (Fru), glucose (Glc), sucrose (Suc) and raffinose (Raf)) increased dramatically in the F(1) plants after cold acclimation as compared to the parental lines. The content of proline (Pro), however, was only moderately increased in the F(1) plants under the same conditions. Correlation analyses showed that only Raf content was consistently related to leaf-freezing tolerance in both the acclimated and NA states. A quantification of mRNA levels in leaves of parental and F(1) lines using quantitative real-time RT-PCR showed no clear indication for an involvement of the investigated genes (CBF (C-repeat binding factor)1, CBF2, (cold-regulated protein (COR) 6.6, COR15a, COR15b, COR47 and COR78) in the Heterosis effect.
Elizabeth S Dennis - One of the best experts on this subject based on the ideXlab platform.
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recent research on the mechanism of Heterosis is important for crop and vegetable breeding systems
Breeding Science, 2018Co-Authors: Ryo Fujimoto, Kosuke Uezono, Sonoko Ishikura, Kenji Osabe, James W Peacock, Elizabeth S DennisAbstract:: Heterosis or hybrid vigor is a phenomenon where hybrid progeny have superior performance compared to their parental inbred lines. This is important in the use of F1 hybrid cultivars in many crops and vegetables. However, the molecular mechanism of Heterosis is not clearly understood. Gene interactions between the two genomes such as dominance, overdominance, and epistasis have been suggested to explain the increased biomass and yield. Genetic analyses of F1 hybrids in maize, rice, and canola have defined a large number of quantitative trait loci, which may contribute to Heterosis. Recent molecular analyses of transcriptomes together with reference to the epigenome of the parents and hybrids have begun to uncover new facts about the generation of Heterosis. These include the identification of gene expression changes in hybrids, which may be important for Heterosis, the role of epigenetic processes in Heterosis, and the development of stable high yielding lines.
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intraspecific arabidopsis hybrids show different patterns of Heterosis despite the close relatedness of the parental genomes
Plant Physiology, 2014Co-Authors: Michael Groszmann, James W Peacock, Rebeca Gonzalezbayon, Ian K Greaves, Li Wang, Amanda K Huen, Elizabeth S DennisAbstract:Heterosis is important for agriculture; however, little is known about the mechanisms driving hybrid vigor. Ultimately, Heterosis depends on the interactions of specific alleles and epialleles provided by the parents, which is why hybrids can exhibit different levels of Heterosis, even within the same species. We characterize the development of several intraspecific Arabidopsis (Arabidopsis thaliana) F1 hybrids that show different levels of Heterosis at maturity. We identify several phases of Heterosis beginning during embryogenesis and culminating in a final phase of vegetative maturity and seed production. During each phase, the hybrids show different levels and patterns of growth, despite the close relatedness of the parents. For instance, during the vegetative phases, the hybrids develop larger leaves than the parents to varied extents, and they do so by exploiting increases in cell size and cell numbers in different ratios. Consistent with this finding, we observed changes in the expression of genes known to regulate leaf size in developing rosettes of the hybrids, with the patterns of altered expression differing between combinations. The data show that Heterosis is dependent on changes in development throughout the growth cycle of the hybrid, with the traits of mature vegetative biomass and reproductive yield as cumulative outcomes of Heterosis at different levels, tissues, and times of development.
Marina Korn - One of the best experts on this subject based on the ideXlab platform.
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predicting arabidopsis freezing tolerance and Heterosis in freezing tolerance from metabolite composition
Molecular Plant, 2010Co-Authors: Marina Korn, Tanja Gartner, Joachim Selbig, Alexander Erban, Joachim Kopka, Dirk K HinchaAbstract:Heterosis, or hybrid vigor, is one of the most important tools in plant breeding and has previously been demonstrated for plant freezing tolerance. Freezing tolerance is an important trait because it can limit the geographical distribution of plants and their agricultural yield. Plants from temperate climates increase in freezing tolerance during exposure to low, non-freezing temperatures in a process termed ‘cold acclimation’. Metabolite profiling has indicated a major reprogramming of plant metabolism in the cold, but it has remained unclear in previous studies which of these changes are related to freezing tolerance. In the present study, we have used metabolic profiling to discover combinations of metabolites that predict freezing tolerance and its Heterosis in Arabidopsis thaliana. We identified compatible solutes and, in particular, the pathway leading to raffinose as crucial statistical predictors for freezing tolerance and its Heterosis, while some TCA cycle intermediates contribute only to predicting the heterotic phenotype. This indicates coordinate links between Heterosis and metabolic pathways, suggesting that a limited number of regulatory genes may determine the extent of Heterosis in this complex trait. In addition, several unidentified metabolites strongly contributed to the prediction of both freezing tolerance and its Heterosis and we present an exemplary analysis of one of these, identifying it as a hexose conjugate.
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Heterosis in the freezing tolerance and sugar and flavonoid contents of crosses between arabidopsis thaliana accessions of widely varying freezing tolerance
Plant Cell and Environment, 2008Co-Authors: Marina Korn, Arnd G Heyer, Silke Peterek, Hans-peter Mock, Dirk K HinchaAbstract:Heterosis is defined as the increased vigour of hybrids in comparison to their parents. We investigated 24 F 1 hybrid lines of Arabidopsis thaliana generated by reciprocally crossing either C24 or Col with six other parental accessions (Can, Co, Cvi, Ler, Rsch, Te) that differ widely in their freezing tolerance. The crosses differed in the degree of Heterosis for freezing tolerance, both in the non-acclimated state and after a 14 d cold acclimation period. Crosses with C24 showed more Heterosis than crosses with Col, and Heterosis was stronger in acclimated than in non-acclimated plants. Leaf content of soluble sugars and proline showed more deviation from mid-parent values in crosses involving C24 than in those involving Col, and deviations were larger in acclimated than in non-acclimated plants. There were significant correlations between the content of different sugars and leaf freezing tolerance, as well as between Heterosis effects in freezing tolerance and sugar content. Flavonoid content and composition varied between accessions, and between non-acclimated and acclimated plants. In the crosses, large deviations from the mid-parent values in the contents of different flavonols occurred, and there were strikingly strong correlations between both flavonol content and freezing tolerance, and between Heterosis effects in freezing tolerance and flavonol content.
