Genetic diversity and comprehensive performance are the basis for the discovery and efficient use of proso millet (Panicum miliaceum L.) core collections.  In this study, 386 proso millet core collections were used as materials to observe inflorescence color, leaf phase, inflorescence density, axis shape, branched spike length, panicle type, trichome, measured area of the top3 leaves, and chlorophyll content of the top3 leaves at filling stage.  These core collections were also used to record growth period, plant height, diameter of main stem, plant tiller number, branch number, panicle length, panicle number per plant, and panicle weight per plant at the maturation stage.  Starch, fat, protein, and yellow pigment contents in the grain and 1 000-seed weight were also measured after harvest.  Then, quantitative traits were used for diversity analysis and comprehensive evaluation of each collection.  Correlations between all traits were also analyzed.  Results showed that among the 8 quality traits, the Shannon index (H´) of hull color was the highest (1.588) followed by the H´ of inflorescence density (0.984).  However, inflorescence color and axis shape were lower.  The H´ of 16 quantitative traits were significantly higher than the quality traits with the following traits having the highest indices: fat content (2.092), 1 000-seed weight (2.073), top3 leaves area (2.070), main stem diameter (2.056), and plant height (2.052).  Furthermore, all other traits had a diversity higher than 1.900.  After a comprehensive evaluation of phenotypic traits, plant height, diameter of main stem, plant tiller number, leaf area of top3 leaves, and 1 000-seed weight were the biggest contributors to the principal components.  Six high-fat and high-protein cultivars, including Nuoshu, A75-2, Zhiduoaosizhi, Panlonghuangmi, Xiaobaishu, and Xiaohongshu were also screened.  Correlations between the quantitative traits were significant, including the correlation between quality traits and quantitative traits.  In conclusion, the core collections can be used as basis for discriminating among proso millet cultivars based on related traits and for further studies on millet with rich genetic diversity, good representation, and significant collection between traits.

Foxtail millet (Setaria italica L.) with high drought resistance, is grown widely in arid and semi-arid regions of the world, and it is a new model plant for genetic and molecular studies.  To uncover the molecular mechanisms of stress-tolerance in different genotypes of foxtail millet, physiological analyses combined with transcriptional profiling were conducted using a time-course analysis on two foxtail millet genotypes Damaomao (DM) and Hongnian (HN).  The genotype DM performed better than HN under water deficiency, with more moderate relative water content (RWC) and chlorophyll decline.  Further physiological and RNA-seq investigations revealed that the two genotypes possessed high conservatism in some vital biological pathways which respond to drought stress, involving hormone synthesis, proline, and soluble sugar synthesis, and reactive oxygen species (ROS) metabolism.  However, some genes related to these pathways showed different expression profiles.  Likewise, the lower malondialdehyde (MDA) content in HN than DM may be explained by the observation that HN contained more activated genes in the ascorbate-glutathione cycle using KEGG pathway analysis.  Overall, abscisic acid (ABA) response genes, ROS scavengers which were probably involved in signaling responses, a set of enzymes involved in proline and soluble sugar synthesis, channel protein genes, and transcription factors, encompassed the early strategy of foxtail millet response to drought.  These findings provide a comprehensive molecular view of how different foxtail millet genotypes respond to short-term osmotic stress.