Background and Aims Elucidating how plant species respond to variable light conditions is important to understand the ecological adaptation to heterogeneous natural habitats. Plant performance and its underlying gene regulatory network have been well documented in sun-grown plants. However, the phenotypic and molecular responses of shade-grown plants under variable light conditions have remained largely unclear. Methods We assessed the differences in phenotypic performance between Panax ginseng (shade-grown) and Arabidopsis (sun-grown) under sunlight, shade and deep-shade conditions. To further address the molecular bases underpinning the phenotypic responses, we compared time-course transcriptomic expression profiling and candidate gene structures between the two species. Key Results Our results show that, compared to the Arabidopsis, ginseng plants not only possess a lower degree of phenotypic plasticity among the three light conditions, but also exhibit higher photosynthetic efficiency under shade and deep-shade conditions. Further comparisons of the gene expression and structure reveal that differentially transcriptional regulation together with increased copy number of the photosynthesis-related genes (i.e., electron transfer and carbon fixation) may improve the photosynthetic efficiency of ginseng plants under the two shade conditions. In contrast, the inactivation of phytochrome-interacting factors (i.e., absent and non-upregulation of the PIFs) are potentially associated with the observed low degree of phenotypic plasticity of ginseng plants under the variable light conditions. Conclusions Our study provides new insights on how the shade-grown plants respond to variable light conditions. Candidate genes related to shade adaptation in ginseng provide valuable genetic resources for future molecular breeding of high-density planting crops.

Lung function impairments, especially airflow obstruction, are important features during acute exacerbation in patients with bronchiectasis. Recognition of the risk factors associated with airflow obstruction is important in the management of these exacerbations. The medical records of adult patients admitted to the Peking University People's Hospital, Beijing, China, from 2004 to 2011 with a diagnosis of bronchiectasis were reviewed retrospectively. Univariate and multivariate analyses were used to evaluate the risk factors associated with airflow obstruction. Airflow obstruction was found in 55.6% of 156 patients hospitalized with acute exacerbation of bronchiectasis, and the risk factors associated with airflow obstruction included young age (14 years old) at diagnosis (odds ratio (OR) ¼ 3.454, 95% confidence interval (CI) 1.709-6.982, p ¼ 0.001) as well as the presence of chronic obstructive pulmonary disease (COPD; OR ¼ 14.677, 95% CI 5.696-37.819, p ¼ 0.001), asthma (OR ¼ 3.063, 95% CI 1.403-6.690, p ¼ 0.005), and wheezing on auscultation (OR ¼ 3.279, 95% CI 1. 495-7.194, p ¼ 0.003). The C-reactive protein (13.9 mg/dl vs. 6.89 mg/ dl, p ¼ 0.005), partial pressure of arterial oxygen (66.7 + 8.57 mmHg vs. 89.56 + 12.80 mmHg, p < 0.001), and partial pressure of arterial carbon dioxide (40.52 + 2.77 mmHg vs. 42.87 + 5.39 mmHg, p ¼ 0.02) profiles were different between patients with or without airflow obstruction. In addition, patients colonized with potential pathogenic microorganisms had a decreased diffusing capacity (56.0% vs. 64.7%, p ¼ 0.04). Abnormal pulmonary function was common in hospitalized patients with bronchiectasis exacerbations. Airflow obstruction was correlated with the patient's age at diagnosis, as well as the presence of combined COPD and asthma, and wheezing on auscultation, which also resulted in more severe systemic inflammation and hypoxemia.

Elucidating how plant species respond to variable light conditions is important to understanding the ecological adaptation to heterogeneous natural habitats. However, the phenotypic responses and gene regulatory network of shade-loving plants under distinct light conditions have remained largely unclear. In this study, we assessed the differences in phenotypic and transcriptomic responses between Arabidopsis (sun-loving) and Panax ginseng (shade-loving) to sunlight and dim-light conditions. Our results showed that, compared to the Arabidopsis, ginseng plants not only exhibited a lower degree of phenotypic plasticity in response to distinct light conditions, but also showed higher photosynthetic efficiency under dim-light conditions. Further time-course transcriptome profiling and gene structural analyses revealed that differentially transcriptional regulation together with increased copy number of the photosynthesis-related genes (i.e., electron transfer and carbon fixation) may improve the photosynthetic efficiency of ginseng plants under dim-light conditions. In contrast, the loss-function and inactivation of phytochrome-interacting factors are potentially associated with the observed low degree of phenotypic plasticity of ginseng plants under the changing light conditions. Our study provides new insights on how shade-loving plants respond to variable light conditions. Candidate genes related to shade adaptation in ginseng provide valuable genetic resources for future molecular breeding of high-density planting crops.

Group Ⅲ WRKY transcription factors (TFs) play pivotal roles in responding to the diverse abiotic stress and secondary metabolism of plants. However, the evolution and function of WRKY66 remains unclear. Here, WRKY66 homologs were traced back to the origin of terrestrial plants and found to have been subjected to both motifs’ gain and loss, and purifying selection. A phylogenetic analysis showed that 145 WRKY66 genes could be divided into three main clades (Clade A–C). The substitution rate tests indicated that the WRKY66 lineage was significantly different from others. A sequence analysis displayed that the WRKY66 homologs had conserved WRKY and C2HC motifs with higher proportions of crucial amino acid residues in the average abundance. The AtWRKY66 is a nuclear protein, salt- and ABA- inducible transcription activator. Simultaneously, under salt stress and ABA treatments, the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities, as well as the seed germination rates of Atwrky66-knockdown plants generated by the clustered, regularly interspaced, short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9) system, were all lower than those of wild type (WT) plants, but the relative electrolyte leakage (REL) was higher, indicating the increased sensitivities of the knockdown plants to the salt stress and ABA treatments. Moreover, RNA-seq and qRT-PCR analyses revealed that several regulatory genes in the ABA-mediated signaling pathway involved in stress response of the knockdown plants were significantly regulated, being evidenced by the more moderate expressions of the genes. Therefore, the AtWRKY66 likely acts as a positive regulator in the salt stress response, which may be involved in an ABA-mediated signaling pathway.

SUMMARYUnderstanding how different driving forces have promoted biological divergence and speciation is one of the central issues in evolutionary biology. The Triticum/Aegilops species complex contains 13 diploid species belonging to the A‐, B‐ and D‐lineages and offers an ideal system to address the evolutionary dynamics of lineage fusion and splitting. Here, we sequenced the whole genomes of one S‐genome species (Aegilops speltoides) of the B‐lineage and four S*‐genome diploid species (Aegilops bicornis, Aegilops longissima, Aegilops sharonensis and Aegilops searsii) of the D‐lineage at the population level. We performed detailed comparisons of the five species and with the other four representative A‐, B‐ and D‐lineage species. Our estimates identified frequent genetic introgressions from A‐ and B‐lineages to the D‐lineage species. A remarkable observation is the contrasting distributions of putative introgressed loci by the A‐ and B‐lineages along all the seven chromosomes to the extant D‐lineage species. These genetic introgressions resulted in high levels of genetic divergence at centromeric regions between Ae. speltoides (B‐lineage) and the other four S*‐genome diploid species (D‐lineage), while natural selection is a potential contributor to divergence among the four S*‐genome species at telomeric regions. Our study provides a genome‐wide view on how genetic introgression and natural selection acted together yet chromosome‐regionally divided to promote genomic divergence among the five S‐ and S*‐genome diploid species, which provides new and nuanced insights into the evolutionary history of the Triticum/Aegilops species complex.