Yazar "Hohn, Christopher E." seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • [ X ]
    Öğe
    Genetic Mapping of Quantitative Trait Loci (QTLs) Associated with Seminal Root Angle and Number in Three Populations of Bread Wheat (Triticum aestivum L.) with Common Parents
    (Springer, 2020) Hohn, Christopher E.; Bektas, Harun
    Drought tolerance of plants is related to their root system architecture. The architecture of a mature plant root system is closely linked to seminal root growth at the seedling stage; hence, selection for root characteristics at the seedling stage may identify genotypes better suited for drought conditions. Here, the genetics of seminal root angle and number were investigated in three doubled haploid mapping populations of wheat. All populations showed significant phenotypic variation for both traits and each demonstrated transgressive segregation. In total, 34 genomic regions were associated with seminal root traits; however, most QTLs were variable from year to year and were population specific. Considering only the results consistent across both years of experiments, five QTLs for seminal root angle were identified on chromosomes 2DS, 5BS, 6AL, 7A, and 7BS, but only the 2DS QTL appeared in two of the three populations. For the seminal root number, one QTL was identified on 4BL. Correlation analyses for seminal root angle, number, and seed weight revealed interesting relationships to consider for future research. In one population, those interactions wrongfully identified QTLs for seed weight as QTLs for seminal root traits. Our findings demonstrate that seminal root angle and number are complex traits and despite high heritability, may be more difficult to unwind than previously proposed.
  • [ X ]
    Öğe
    On the Possible Trade-Off between Shoot and Root Biomass in Wheat
    (Mdpi, 2023) Bektas, Harun; Hohn, Christopher E.; Lukaszewski, Adam J.; Waines, John Giles
    Numerous studies have shown that under a limited water supply, a larger root biomass is associated with an increased above-ground biomass. Root biomass, while genetically controlled, is also greatly affected by the environment with varying plasticity levels. In this context, understanding the relationship between the biomass of shoots and roots appears prudent. In this study, we analyze this relationship in a large dataset collected from multiple experiments conducted up to different growth stages in bread wheat (Triticum aestivum L.) and its wild relatives. Four bread wheat mapping populations as well as wild and domesticated members of the Triticeae tribe were evaluated for the root and shoot biomass allocation patterns. In the analyzed dataset the root and shoot biomasses were directly related to each other, and to the heading date, and the correlation values increased in proportion to the length of an experiment. On average, 84.1% of the observed variation was explained by a positive correlation between shoot and root biomass. Scatter plots generated from 6353 data points from numerous experiments with different wheats suggest that at some point, further increases in root biomass negatively impact the shoot biomass. Based on these results, a preliminary study with different water availability scenarios and growth conditions was designed with two cultivars, Pavon 76 and Yecora Rojo. The duration of drought and water level significantly affected the root/shoot biomass allocation patterns. However, the responses of the two cultivars were quite different, suggesting that the point of diminishing returns in increasing root biomass may be different for different wheats, reinforcing the need to breed wheats for specific environmental challenges.
  • [ X ]
    Öğe
    Preliminary tests indicate the absence of polymorphism among 1RS.1BL translocations in wheat for root biomass enhancement
    (Springer, 2021) Hohn, Christopher E.; Bektas, Harun
    The introduction of the short arm of rye chromosome 1R (1RS) into wheat significantly increased grain yields. Studies have shown that 1RS carries a locus controlling root biomass and improves canopy water status under water-stressed conditions. The general genetic map location of the locus is known but allelic variation would facilitate precise mapping and identification of the responsible gene(s). To this end, six 1RS.1BL translocations from various sources in three wheat backgrounds were tested for root biomass and response to drought but no significant differences among different 1RS arms were observed. The behavior of the standard 1RS.1BL translocation in cv. Pavon 76 in various experiments suggested that wheat chromosome arm 1BS of Pavon 76 may carry a locus for root system plasticity. A set of single substitutions of chromosome 1B from 15 different sources, in the same genetic background of cv. Pavon 76, were tested for root biomass in various experiments. Again, no significant variation among the 1B substitution lines was observed. These results suggest that either no allelic variation at the targeted loci exists, or the sets of lines were biased. While various 1B chromosomes originated from a random sample of wheats, all 1RS arms were imported into wheat from various triticales, perhaps preselecting certain allelic combinations.