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Browsing by Author "Krampis, Konstantinos"

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    Genetic variants in root architecture-related genes in a Glycine soja accession, a potential resource to improve cultivated soybean
    Prince, Silvas J.; Li, Song; Qiu, Dan; Maldonado dos Santos, Joao V.; Chai, Chenglin; Joshi, Trupti; Patil, Gunvant; Valliyodan, Babu; Vuong, Tri D.; Murphy, Mackensie; Krampis, Konstantinos; Tucker, Dominic M.; Biyashev, Ruslan M.; Dorrance, Anne E.; Saghai-Maroof, Mohammad A.; Xu, Dong; Shannon, J. Grover; Nguyen, Henry T. (2015-02-25)
    Background Root system architecture is important for water acquisition and nutrient acquisition for all crops. In soybean breeding programs, wild soybean alleles have been used successfully to enhance yield and seed composition traits, but have never been investigated to improve root system architecture. Therefore, in this study, high-density single-feature polymorphic markers and simple sequence repeats were used to map quantitative trait loci (QTLs) governing root system architecture in an inter-specific soybean mapping population developed from a cross between Glycine max and Glycine soja. Results Wild and cultivated soybean both contributed alleles towards significant additive large effect QTLs on chromosome 6 and 7 for a longer total root length and root distribution, respectively. Epistatic effect QTLs were also identified for taproot length, average diameter, and root distribution. These root traits will influence the water and nutrient uptake in soybean. Two cell division-related genes (D type cyclin and auxin efflux carrier protein) with insertion/deletion variations might contribute to the shorter root phenotypes observed in G. soja compared with cultivated soybean. Based on the location of the QTLs and sequence information from a second G. soja accession, three genes (slow anion channel associated 1 like, Auxin responsive NEDD8-activating complex and peroxidase), each with a non-synonymous single nucleotide polymorphism mutation were identified, which may also contribute to changes in root architecture in the cultivated soybean. In addition, Apoptosis inhibitor 5-like on chromosome 7 and slow anion channel associated 1-like on chromosome 15 had epistatic interactions for taproot length QTLs in soybean. Conclusion Rare alleles from a G. soja accession are expected to enhance our understanding of the genetic components involved in root architecture traits, and could be combined to improve root system and drought adaptation in soybean.
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    Infection and genotype remodel the entire soybean transcriptome
    Zhou, Lecong; Mideros, Santiago X.; Bao, Lei; Hanlon, Regina; Arredondo, Felipe D.; Tripathy, Sucheta; Krampis, Konstantinos; Jerauld, Adam; Evans, Clive; St Martin, Steven K.; Saghai-Maroof, Mohammad A.; Hoeschele, Ina; Dorrance, Anne E.; Tyler, Brett M. (2009-01-26)
    Background High throughput methods, such as high density oligonucleotide microarray measurements of mRNA levels, are popular and critical to genome scale analysis and systems biology. However understanding the results of these analyses and in particular understanding the very wide range of levels of transcriptional changes observed is still a significant challenge. Many researchers still use an arbitrary cut off such as two-fold in order to identify changes that may be biologically significant. We have used a very large-scale microarray experiment involving 72 biological replicates to analyze the response of soybean plants to infection by the pathogen Phytophthora sojae and to analyze transcriptional modulation as a result of genotypic variation. Results With the unprecedented level of statistical sensitivity provided by the high degree of replication, we show unambiguously that almost the entire plant genome (97 to 99% of all detectable genes) undergoes transcriptional modulation in response to infection and genetic variation. The majority of the transcriptional differences are less than two-fold in magnitude. We show that low amplitude modulation of gene expression (less than two-fold changes) is highly statistically significant and consistent across biological replicates, even for modulations of less than 20%. Our results are consistent through two different normalization methods and two different statistical analysis procedures. Conclusion Our findings demonstrate that the entire plant genome undergoes transcriptional modulation in response to infection and genetic variation. The pervasive low-magnitude remodeling of the transcriptome may be an integral component of physiological adaptation in soybean, and in all eukaryotes.
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    Systems View Of The Soybean Genetic Mechanisms Involved In The Response To Plant Pathogen Infection
    Krampis, Konstantinos (Virginia Tech, 2009-04-17)
    This thesis involves the important crop plant soybean (Glycine max), and provides a rich information resource for breeders and geneticists working towards improving traits for pathogen resistance.Results reported here provide a systemic view at both the genetic and biochemical level, and were generated by data-mining gene expression data from soybean cultivars inoculated with plant pathogens and also recombinant inbred line (RIL) populations.The genome variability based on Single Feature Polymorphisms (SFPs) was measured for the first time in soybean, using a genetically diverse set of cultivated G. max lines and also a G. soja line. Additionally, a genetic map spanning all 20 soybean chromosomes groups were assembled in a large RIL population.The well studied metabolic pathways from the model plant Arabidopsis thaliana, were reconstructed in G. max based on sequence similarity comparison between the genomes of the two species. We performed algorithmic analysis of pathways in our set of soybean lines and RILs using the gene expression data, and acquired a systemic view of the metabolic response to pathogen infection in different genetic backgrounds.Significant differences in the patterns of pathway perturbation was observed in the different lines, and also between four different chromosomal regions that have been known to contain genetic elements contributing to pathogen resistance.