Salt stress directly affects the growth of plants. The limitation of leaf grow is among the earliest visible effects of salt stress. However, the regulation mechanism of salt treatments on leaf shape has not been fully elucidated. We measured the morphological traits and anatomical structure. In combination with transcriptome analysis, we analyzed differentially expressed genes (DEGs) and verified the RNA-seq data by qRT-PCR. Finally, we analyzed correlation between leaf microstructure parameters and expansin genes. We show that the leaf thickness, the width, and the leaf length significantly increased at elevated salt concentrations after salt stress for 7 days. Low salt mainly promoted the increase in leaves length and width, but high salt concentration accelerated the leaf thickness. The anatomical structure results indicated that palisade mesophyll tissues contribute more to leaf thickness than spongy mesophyll tissues, which possibly contributed to the increase in leaf expansion and thickness. Moreover, a total of 3,572 DEGs were identified by RNA-seq. Notably, six of the DEGs among 92 identified genes concentrated on cell wall synthesis or modification were involved in cell wall loosening proteins. More importantly, we demonstrated that there was a strong positive correlation between the upregulated EXLA2 gene and the thickness of the palisade tissue in L. barbarum leaves. These results suggested that salt stress possibly induced the expression of EXLA2 gene, which in turn increased the thickness of L. barbarum leaves by promoting the longitudinal expansion of cells of the palisade tissue. This study lays a solid knowledge for revealing the underlying molecular mechanisms of leaf thickening in L. barbarum in response to salt stresses.

Salt stress seriously affects yield and quality of crops. The fruit of Lycium barbarum (LBF) is extensively used as functional food due to its rich nutrient components. It remains unclear how salt stress influences the quality of LBF. In this study, we identified 71 differentially accumulated metabolites (DAMs) and 1396 differentially expressed genes (DEGs) among ripe LBF with and without 300 mM of NaCl treatment. Pearson correlation analysis indicated that the metabolomic changes caused by salt stress were strongly related to oxidoreductases; hydrolases; and modifying enzymes, in particular, acyltransferases, methyltransferases and glycosyltransferases. Further analysis revealed that salt stress facilitated flavonoid glycosylation and carotenoid esterification by boosting the expression of structural genes in the biosynthetic pathways. These results suggested that salt stress prompts the modification of flavonoids and carotenoids to alleviate ROS damage, which in turn improves the quality of LBF. Our results lay a solid foundation for uncovering the underlying molecular mechanism of salt stress orchestrating LBF quality, and the candidate genes identified will be a valuable gene resource for genetic improvement of L. barbarum.

The use of chemical fertilizer along with organic fertilizer is an important agricultural practice that improves crop yield but also affects soil biogeochemical cycles. In this study, a maize field experiment was conducted to investigate the effects of NPK fertilizer (NPK), organic fertilizer (OF), and their combination (NPK+OF) on soil chemical properties, bacterial and fungal community structures, and diversity compared the control (CK, without any fertilizer). The results showed that the application of OF and NPK-combined OF increased soil organic matter (OM), total N, total P, available N, available P, and available K levels. For alpha diversity analyses, the application of fertilizers led to decreases in soil bacterial and fungal Shannon indices (except for NPK in fungi). Compared with CK, NPK, OF, and NPK+OF fertilization treatments significantly increased the abundances of Acidobacteriota, Gemmatimonadota, and Basidiomycota. Network analysis showed that fertilization produced fewer connections among microbial taxa, especially in the combination of NPK and OF. A redundancy analysis combined with Mantel test further found that the soil OM, available N and P were the main soil-fertility factors driving microbial community variations. Therefore, using organic fertilizer or biological fertilizer combined with chemical fertilizer to improve the status of soil C, N, and P is a promising method to maintain the balance of soil microorganisms in maize field.

Effects of organic fertilizers on organic carbon accumulation in alkalized saline soil and silage maize yield