Integrated physiological, biochemical, and transcriptomics analyses reveal the underlying mechanisms of high nitrogen use efficiency of black sesame.

Cultivating high nitrogen use efficient varieties is a sustainable solution to mitigating adverse effects on the environment caused by excessive nitrogen fertilizer application. However, in sesame, although immoderate nitrogen fertilizers are used to promote yield, the molecular basis of high nitrogen use efficiency (NUE) is largely unknown. Hence, this study aimed to identify high NUE black sesame variety and dissect the underlying physiological and molecular mechanisms. To achieve this, seventeen seedling traits of 30 black sesame varieties were evaluated under low nitrogen (LN) and high nitrogen (HN) conditions. Dry matter accumulation, root parameters, shoot nitrogen accumulation, and chlorophyll content are important factors for evaluating the NUE of sesame genotypes. The variety 17-156 was identified as the most efficient for N utilization. Comparative physiological and transcriptomics analyses revealed that 17-156 possesses a sophisticated nitrogen metabolizing machinery to uptake and assimilate higher quantities of inorganic nitrogen into amino acids and proteins, and simultaneously improving carbon metabolism and growth. Specifically, the total nitrogen and soluble protein contents significantly increased with the increase in nitrogen concentrations. Many important genes, including nitrate transporters (NPFs), amino acid metabolism-related (GS, GOGAT, GDH, etc.), phytohormone-related, and transcription factors, were significantly up-regulated in 17-156 under HN condition. In addition, 38 potential candidate genes were identified for future studies toward improving sesame's NUE. These findings offer valuable resources for deciphering the regulatory network of nitrogen metabolism and developing sesame cultivars with improved NUE.

Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.

OBJECTIVE: Increased levels of reaction time variability (RTV) are characteristics of sustained attention deficits. The clinical significance of RTV has been widely recognized. However, the reliability of RTV measurements has not been widely studied. The present study aimed to assess the test-retest reliability of RTV conventional measurements, e.g., the standard deviation (SD), the coefficient of variation (CV), and a new measurement called the amplitude of low frequency fluctuation (ALFF) of RT. In addition, we aimed to assess differences and similarities of these measurements between different tasks. METHOD: Thirty-seven healthy college students participated in 2 tasks, i.e., an Eriksen flanker task (EFT) and a simple reaction task (SRT), twice over a mean interval of 56 days. Conventional measurements of RTV including RT-SD and RT-CV were assessed first. Then the RT time series were converted into frequency domains, and RT-ALFF was further calculated for the whole frequency band (0.0023-0.167 Hz) and for a few sub-frequency bands including Slow-6 (<0.01 Hz), Slow-5 (0.01-0.027 Hz), Slow-4 (0.027-0.073 Hz), and Slow-3 (0.073-0.167 Hz). The test-retest reliability of these measurements was evaluated through intra-class correlation (ICC) tests. Differences and correlations between each EFT and SRT measurement were further examined during both visits. RESULTS: 1) The RT-ALFF of the Slow-5/4/3 and conventional measurements of RT-SD and RT-CV showed moderate to high levels of test-retest reliability. EFT RT-ALFF patterns generated slightly higher ICC values than SRT values in higher frequency bands (Slow-3), but SRT RT-ALFF values showed slightly higher ICC values than EFT values in lower frequency bands (Slow-5 and Slow-4). 2) RT-ALFF magnitudes in each sub-frequency band were greater for the SRT than those for the EFT. 3) The RT-ALFF in the Slow-4 of the EFT was found to be correlated with the RT-ALFF in the Slow-5 of the SRT for both two visits, but no consistently significant correlation was found between the same frequency bands. CONCLUSIONS: These findings reveal good test-retest reliability for conventional measurements and for the RT-ALFF of RTV. The RT-ALFF presented frequency-dependent similarities across tasks. All of our results reveal the presence of different frequency structures between the two tasks, and thus the frequency-dependent characteristics of different tasks deserve more attention in future studies.