Alfalfa (Medicago sativa L.) is one of the most important forage resources in the world due to its high nutritive value. However, its nutritional quality decreases during the transition from budding to flowering. Previous research revealed a decreased crude protein content and increased fibre content in alfalfa forage harvested at later maturity stages, leading to a reduction in nutritional quality. However, the reasons for this phenomenon have not been explained at the molecular level. In this study, leaves from the WL319HQ alfalfa cultivar were harvested at two developmental stages (budding and mid-flowering). The leaves were used to test the variable expression of proteins and metabolites during these stages. TMT-based quantitative proteomics and LC-MS/MS-based untargeted metabolomics methods were employed in this study. A total of 415 proteins and 49 metabolites showed at least a 1.2-fold difference in abundance during these stages. Most of the differentially expressed proteins and metabolites were involved in metabolic processes, including carbohydrate metabolism, starch and sucrose metabolism, phenylpropanoid biosynthesis, and biosynthesis of amino acids. Alfalfa leaves in mid-flowering contain less crude protein due to the decrease in L-glutamic acid content. Carbohydrate metabolism provides the raw material for the synthesis of hemicellulose, resulting in an increase in the hemicellulose content of the alfalfa leaves, leading to an increase in the NDF content. In addition, the increase in L-phenylalanine content could have provided the conditions necessary for lignin synthesis. These are the main factors leading to reductions in alfalfa relative feed value (RFV) and quality. This study used joint proteomic and metabolomic analyses to elucidate the relationship between the reduction in the nutritional value of alfalfa and complex biological processes. This provides a theoretical basis for producing high-quality alfalfa hay and sets the stage for further research.

Increasing soil salinization can severely restrict local agricultural production. Planting alfalfa is considered an effective measure to ameliorate saline–alkali soil. However, it remains unclear how alfalfa planting years affect the sustained impact on soil and rhizosphere microecology. This study analyzed the effects of alfalfa planted 3, 6, and 8 years ago on soil physicochemical properties and key soil enzyme activities and investigated the rhizosphere microbial community structure and diversity. The results indicate that cultivating alfalfa plants for six years can improve soil physicochemical properties and enhance soil fertility to a certain extent. This is attributed to a higher abundance of plant growth-promoting bacteria, such as Bradyrhizobium and Allorhizobium, as well as degradation bacteria, such as Flavobacterium, Stenotrophomonas, Brevundimonas, and Massilia, in the rhizosphere of alfalfa plants. These microorganisms promote alfalfa growth, improve soil quality, and inhibit the accumulation of autotoxins. This not only maintains high alfalfa yields but also optimizes soil physicochemical properties and enzyme activity, facilitating more effective nutrient cycling and metabolic processes in the soil. However, extending plant growth to 8 years is not beneficial.

As one of the environmental factors that seriously affect plant growth and crop production, drought requires an efficient but environmentally neutral approach to mitigate its harm to plants. Soil microbiomes can interact with plants and soil to improve the adverse effects of drought. Medicago ruthenica (L.) is an excellent legume forage with strong drought tolerance, but the key role of microbes in fighting drought stress remains unclear. What kind of flora plays a key role? Is the recruitment of such flora related to its genotype? Therefore, we selected three varieties of M. ruthenica (L.) for drought treatment, analyzed their growth and development as well as their physiological and biochemical characteristics, and performed 16S rRNA high-throughput sequencing analysis on their rhizosphere soils to clarify the variety-mediated response of rhizosphere bacteria to drought stress. It was found that among the three varieties of M. ruthenica (L.), Mengnong No.2, Mengnong No.1 and Zhilixing were subjected to drought stress and showed a reduction in plant height increment of 24.86%, 34.37%, and 31.97% and in fresh weight of 39.19%, 50.22%, and 41.12%, respectively, whereas dry weight was reduced by 23.26%, 26.10%, and 24.49%, respectively. At the same time, we found that the rhizosphere microbial community of Mengnong No. 2 was also less affected by drought, and it was able to maintain the diversity of rhizosphere soil microflora stable after drought stress, while Mennong No. 1 and Zhilixing were affected by drought stress, resulting in a decrease in rhizosphere soil bacterial community diversity indices to 92.92% and 82.27%, respectively. Moreover, the rhizosphere of Mengnon No. 2 was enriched with more nitrogen-fixing bacteria Rhizobium than the other two varieties of M. ruthenica (L.), which made it still have a good ability to accumulate aboveground biomass after drought stress. In conclusion, this study proves that the enrichment process of bacteria is closely related to plant genotype, and different varieties enrich different types of bacteria in the rhizosphere to help them adapt to drought stress, and the respective effects are quite different. Our results provide new evidence for the study of bacteria to improve the tolerance of plants to drought stress and lay a foundation for the screening and study mechanism of drought-tolerant bacteria in the future.

Background: To accelerate the establishment of a genetic improvement system for Onobrychis viciaefolia Scop. by cultivating haploid plants and producing pure parental material. Methods: We endeavored to set up the Onobrychis viciaefolia Scop. anther culture system, examine the suitable anther pre-treatment method and the factors influencing medium type and hormone ratio during anther regeneration. Result: The regenerative capacity of intact anthers was preserved by 48h low temperature (4°C) medium treatment. Or the broken anthers were obtained when the regenerated grass was budding and preserved in the medium after 48 hours of low temperature treatment; callus induction was based on MS and the callus rate was 18.33% when 1.0 mg/L 2,4-D + 0.75 mg/L 6-BA + 0.8 mg/L NAA + 2.0 mg/L KT was added. With N6 as the basic medium, the addition of 2.0 mg/L 2,4-D + 0.75 mg/L 6-BA + 0.4 mg/L NAA + 0.5 mg/L KT resulted in a healing rate of 16.19%; the addition of 0.5 mg/L 6-BA + 1.0 mg/L KT to the MS medium resulted in a differentiation rate of 68%; during the construction of the anther histoponic system, browning and waterlogging of the healing tissues and vitrification of the seedlings hindered the formation of regenerated plants.