Genome-wide investigation of NLP gene family members in alfalfa (Medicago sativa L.): evolution and expression profiles during development and stress.

BACKGROUND: NIN-like protein (NLP) transcription factors (TFs) compose a plant-specific gene family whose members play vital roles in plant physiological processes, especially in the regulation of plant growth and the response to nitrate-nitrogen. However, no systematic identification or analysis of the NLP gene family has been reported in alfalfa. The recently completed whole-genome sequence of alfalfa has allowed us to investigate genome-wide characteristics and expression profiles. RESULTS: 53 MsNLP genes were identified from alfalfa and renamed according to their respective chromosome distributions. Phylogenetic analysis demonstrated that these MsNLPs can be classified into three groups on the basis of their conserved domains. Gene structure and protein motif analyses showed that closely clustered MsNLP genes were relatively conserved within each subgroup. Synteny analysis revealed four fragment duplication events of MsNLPs in alfalfa. The ratios of nonsynonymous (Ka) and synonymous (Ks) substitution rates of gene pairs indicated that the MsNLP genes underwent purifying selection during evolution. Examination of the expression patterns of different tissues revealed specific expression patterns of the MsNLP genes in the leaves, indicating that these genes are involved in plant functional development. Prediction of cis-acting regulatory elements and expression profiles further demonstrated that the MsNLP genes might play important roles in the response to abiotic stress and in phytohormone signal transduction processes. CONCLUSION: This study represents the first genome-wide characterization of MsNLP in alfalfa. Most MsNLPs are expressed mainly in leaves and respond positively to abiotic stresses and hormonal treatments. These results provide a valuable resource for an improved understanding of the characteristics and biological roles of the MsNLP genes in alfalfa.

In Vitro Stability and Pharmacokinetic Study of Pedunculoside and Its Beta-CD Polymer Inclusion Complex.

Pedunculoside, a triterpene saponin derived from various Ilex species, holds potential as a treatment for cardiovascular diseases. However, its clinical application is hindered by poor bioavailability, rapid elimination, and extensive intestinal metabolism to rotundic acid. To address these issues, a water-soluble inclusion complex of pedunculoside, namely, the beta-CD polymer inclusion complex of pedunculoside (pedunculoside-ßCDP), was prepared in this study, and a comparative in vitro stability and pharmacokinetic behavior study was performed between pedunculoside and pedunculoside-ßCDP. Both pedunculoside and pedunculoside-ßCDP exhibited the highest stability in simulated gastric fluid and simulated intestinal fluid but were readily metabolized when co-incubated with Bifidobacterium adolescentis and Bifidobacterium breve. An LC-MS/MS analytical method for the simultaneous determination of pedunculoside and rotundic acid in rat plasma was successfully established, validated, and applied to investigate the pharmacokinetic behavior after rats were intravenously administered with pedunculoside or pedunculoside-ßCDP. The results indicated that pedunculoside-ßCDP could significantly improve the pharmacokinetic profile of pedunculoside by increasing plasma exposure, retarding elimination, and reducing intestinal metabolism. This study enhances our understanding of pedunculoside-ßCDP's metabolic fate and pharmacokinetic properties and potentially advances its further research, development, and clinical application.

The Multiple Promoting Effects of Suaeda glauca Root Exudates on the Growth of Alfalfa under NaCl Stress.

Under abiotic stress, plant root exudates can improve plant growth performance. However, studies on the effect of root exudates on the stress resistance of another plant are insufficient. In this study, root exudates (REs) were extracted from Suaeda glauca to explore their effect on alfalfa seedlings under salt stress. The results showed that the plant height and fresh weight of alfalfa significantly increased by 47.72% and 53.39% after 7 days of RE treatment at a 0.4% NaCl concentration. Under 1.2% salt stress, REs reduced the Malondialdehyde content in alfalfa by 30.14% and increased the activity of its antioxidant enzymes (peroxidase and catalase) and the content of its osmotic regulators (soluble sugar and proline) by 60.68%, 52%, 45.67%, and 38.67%, respectively. Soil enzyme activity and the abundance of soil-beneficial bacteria were increased by REs. Spearman analysis showed that urease and neutral phosphatase were related to the richness of beneficial bacteria. Redundancy analysis confirmed that urease affected the composition of the soil bacterial community. The partial least squares structural equation model (PLS-SEM) revealed that REs had a direct positive effect on alfalfa growth under salt stress by regulating the plant's injury and antioxidant systems, and the soil bacterial community had an indirect positive effect on alfalfa growth through soil enzyme activity.