Heterotic Trait Locus (HTL) Mapping Identifies Intra-Locus Interactions That Underlie Reproductive Hybrid Vigor in Sorghum bicolor

Identifying intra-locus interactions underlying heterotic variation among whole-genome hybrids is a key to understanding mechanisms of heterosis and exploiting it for crop and livestock improvement. In this study, we present the development and first use of the heterotic trait locus (HTL) mapping approach to associate specific intra-locus interactions with an overdominant heterotic mode of inheritance in a diallel population using Sorghum bicolor as the model. This method combines the advantages of ample genetic diversity and the possibility of studying non-additive inheritance. Furthermore, this design enables dissecting the latter to identify specific intra-locus interactions. We identified three HTLs (3.5% of loci tested) with synergistic intra-locus effects on overdominant grain yield heterosis in 2 years of field trials. These loci account for 19.0% of the heterotic variation, including a significant interaction found between two of them. Moreover, analysis of one of these loci (hDPW4.1) in a consecutive F2 population confirmed a significant 21% increase in grain yield of heterozygous vs. homozygous plants in this locus. Notably, two of the three HTLs for grain yield are in synteny with previously reported overdominant quantitative trait loci for grain yield in maize. A mechanism for the reproductive heterosis found in this study is suggested, in which grain yield increase is achieved by releasing the compensatory tradeoffs between biomass and reproductive output, and between seed number and weight. These results highlight the power of analyzing a diverse set of inbreds and their hybrids for unraveling hitherto unknown allelic interactions mediating heterosis

Culture, geography, and the arts of government

This paper endeavors to prise open the theoretical closure of the conceptualization of culture in contemporary human geography. Foucault's later work on government provides the basis for a useable definition of culture as an object of analysis which avoids problems inherent in abstract, generalizing and expansive notions of culture. The emergence of this Foucauldian approach in cultural studies is discussed, and the distinctive conceptualization of the relations between culture and power that it implies are elaborated. This re-conceptualization informs a critical project of tracking the institutional formation of the cultural and the deployment of distinctively cultural forms of regulation into the fabric of modern social life. It is argued that the culture-and-government approach needs to be supplemented by a more sustained consideration of the spatiality and scale of power-relations. It is also suggested that this approach might through into new perspective the dynamics behind geography's own cultural turn

Gautieria

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Geastrum recolligens

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Cyathus stercoreus

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Stropharia

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Cyathus stercoreus

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Tulostoma

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Battarrea stevenii

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