Impact of Sprouting under Potassium Nitrate Priming on Nitrogen Assimilation and Bioactivity of Three Medicago Species

Edible sprouts are rich in flavonoids and other polyphenols, as well as proteins, minerals, and vitamins. Increasing sprout consumption necessitates improving their quality, palatability, and bioactivity. The purpose of this study was to test how KNO3 priming affects the sprouting process species on three Medicago species (Medicago indicus, Medicago interexta, and Medicago polymorpha) and their nutritional values. Targeted species of Medicago were primed with KNO3, and the levels of different primary and secondary metabolites were determined. KNO3 induced biomass accumulation in the sprouts of the three species, accompanied by an increased content of total mineral nutrients, pigments, vitamins, and essential amino acids. Besides, our results showed that KNO3 enhanced the activity of nitrate reductase (NR), glutamate dehydrogenase (GDH), and glutamine synthetase (GS) enzymes, which are involved in the nitrogen metabolism and GOGAT cycle, which, in turn, increase the nitrogen and protein production. KNO3 treatment improved the bioactive compound activities of Medicago sprouts by increasing total phenolic and flavonoid contents and enhancing the antioxidant and antidiabetic activities. Furthermore, species-specific responses toward KNO3 priming were noticeable, where Medicago interexta showed the highest antioxidant and antidiabetic activities, followed by Medicago polymorpha. Overall, this study sheds the light on the physiological and biochemical bases of growth, metabolism, and tissue quality improvement impact of KNO3 on Medicago sprouts.

Molecular and morphological characterization related to salt stress in natural populations of the Medicago polymorpha species

Legumes are important crops due to their nutritional benefits as well as their utility in agriculture rotation. The morphological and molecular markers can elucidate plant response to stresses. In the present study, we investigated indicators of molecular polymorphism related to salt stress tolerance in natural populations of Medicago polymorpha species. The plant samples were collected from different geographical sites in western Algeria. Morphological growth parameters such as root length stem length of plant and T/R ratio were examined under four NaCl concentration levels (0, 68, 102 and 137 mM). The molecular study was carried out using SSR molecular markers on all the studied populations. Significant differences were observed in mean squares of analysis of variance, indicating relation between geographical origins and populations. This analysis showed the existence of two contrasted populations (DZ221 and DZ312). DZ221 is a relatively salt tolerant, and DZ312 is sensitive. The Principal Component Analysis (PCA) was calculated using the PCA function, revealing a high correlation between the morphological traits and the geographical distribution of populations. It divided populations into four distinguished groups respecting their origin geographical sites. The molecular results of the polymorphism degree showed that the natural populations of M. Polymorpha species were strictly homozygous (100%). The PIC index of the three microsatellites was very informative (0.77). Additionally, the results showed that both microsatellites (FMT11 and MTIC297) revealed some alleles detected in the tolerant population (DZ221) suggesting that they can be used as indicators of saline stress tolerance adaptation.

The genome of Medicago polymorpha provides insights into its edibility and nutritional value as a vegetable and forage legume

Medicago polymorpha is a nutritious and palatable forage and vegetable plant that also fixes nitrogen. Here, we reveal the chromosome-scale genome sequence of M. polymorpha using an integrated approach including Illumina, PacBio and Hi-C technologies. We combined PacBio full-length RNA-seq, metabolomic analysis, structural anatomy analysis and related physiological indexes to elucidate the important agronomic traits of M. polymorpha for forage and vegetable usage. The assembled M. polymorpha genome consisted of 457.53 Mb with a long scaffold N50 of 57.72 Mb, and 92.92% (441.83 Mb) of the assembly was assigned to seven pseudochromosomes. Comparative genomic analysis revealed that expansion and contraction of the photosynthesis and lignin biosynthetic gene families, respectively, led to enhancement of nutritious compounds and reduced lignin biosynthesis in M. polymorpha. In addition, we found that several positively selected nitrogen metabolism-related genes were responsible for crude protein biosynthesis. Notably, the metabolomic results revealed that a large number of flavonoids, vitamins, alkaloids, and terpenoids were enriched in M. polymorpha. These results imply that the decreased lignin content but relatively high nutrient content of M. polymorpha enhance its edibility and nutritional value as a forage and vegetable. Our genomic data provide a genetic basis that will accelerate functional genomic and breeding research on M. polymorpha as well as other Medicago and legume plants.

Legume Ecotypes and Commercial Cultivars Differ in Performance and Potential Suitability for Use as Permanent Living Mulch in Mediterranean Vegetable Systems

Weed control in organic conservative vegetable systems is extremely challenging and the use of legume permanent living mulches (pLM) presents an interesting opportunity. The successful use of pLM is largely determined by the choice of appropriate legumes which are able to combine adequate weed control with a marginal competitive effect on the cash crop(s). However, the availability of legumes for such systems is limited and their characterization based on growth traits can support the selection of suitable legumes for conservation organic vegetable systems. The current study investigated weed control capacity and variability in morphological and phenological traits relevant in inter-plant competition among a range of 11 commercial cultivars of legumes and seven ecotypes of Medicago polymorpha (bur medic). For commercial cultivars, Lotus corniculatus (bird’s-foot trefoil) and Trifolium repens (white clover) showed the best weed control capacity, while Trifolium subterraneum (subterranean clover) and Medicago polymopha had more suitable characteristics for a rapid and complete establishment of the pLM. Overall, legume mulches appear more effective in dicotyledonous than in monocotyledonous weed control. Trifolium subterraneum cv. Antas and T. repens cv. Haifa were identified as the potentially most suitable legumes for use as pLM and their use in mixtures could be a promising solution. In addition, the ecotypes of Medicago polymorpha Manciano and Talamone proved to be well adapted for local environmental conditions and they showed a better weed suppression than the commercial cultivars of Medicago polymorpha.