Seed size and weight are key traits determining crop yield, which often undergo strongly artificial selection during crop domestication. Although seed sizes differ significantly between oil flax and fiber flax, the genetic basis of morphological differences and artificial selection characteristics in seed size remains largely unclear. Here we resequenced 200 flax cultivated accessions to generate a genome variation map based on chromosome assembly reference genomes. We provide evidence that oil flax group is the ancestor of cultivated flax, and the oil-fiber dual purpose group (OF) is the evolutionary intermediate transition state between oil and fiber flax. Genome-wide association studies (GWAS) were combined with LD Heatmap to identify candidate regions related to seed size and weight, then candidate genes were screened based on detailed functional annotations and estimation of nucleotide polymorphism effects. Using this strategy, we obtained 13 candidate genes related to seed size and weight. Selective sweeps analysis indicates human-involved selection of small seeds during the oil to fiber flax transition. Our study shows the existence of elite alleles for seed size and weight in flax germplasm and provides molecular insights into approaches for further improvement.

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In this article, the comprehensive evaluation of water resource carrying capacity (for short WRCC) in Shiyang River Basin is the objective. Based on the comprehensive evaluation model of regional WRCC, the spatial and temporal change characteristics of the WRCC in Shiyang River Basin in 2007, 2011 and 2016 have been analyzed. Moreover, the influence elements of water resource carrying capacity in Shiyang River Basin are detected by the geographical detector. The results show that: (1) In terms of the spatial dimension, water resources in Shiyang River Basin are not in accordance with the distribution of social and economic development and population distribution, presenting a prominent contradiction between supply and demand of water resources; (2) in terms of the temporal dimension, the pressure on water resources in Shiyang River Basin has gradually increased, and the area of overload, light overload and serious overload has been augmented; (3) the geographical detector indicates that the influences of the water resources system and coordinating system factors are declining, and the influences of the social economy system and ecological factor are obviously increasing. The influences of the interaction with any two factors are stronger than that of a single factor, and the synergistic influences of two factors are aggravated.

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