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Abstract: Medicago varia is a very important legume forage with a high yield and good nutrient quality. It is widely cultivated in the middle‐eastern regions of China. However, drought is one of the major abiotic stresses that reduce Medicago varia growth and production. 5‐aminolevulinic acid (5‐ALA) is a physiologically active substance in plants with the potential to improve agricultural production. Exogenous application of 5‐ALA is able to increase plant resistance to multiple abiotic stresses. In this study, the effects of different concentrations of 5‐ALA (0, 5, 10, 20, 30 mg L−1) on seed germination and seedling growth of Medicago varia under drought stress was investigated. The results showed that seed germination was reduced significantly under drought stress. However, exogenous 5‐ALA significantly increased the final germination percentage (FGP) and reduced mean germination time (MGT), indicating that 5‐ALA promoted seed germination of Medicago varia under drought stress. In addition, the rate of cotyledon protruding seed coat, seedlings biomass, radicle length, chlorophyll content of cotyledon, aperture width of stomata and pore area of stomata were increased significantly and stomatal density of cotyledon was reduced significantly by 5‐ALA under drought stress. Collectively, our data suggest that 5‐ALA can be applied to promote seed germination of M. varia under drought stress. [ABSTRACT FROM AUTHOR]

There are many bare and cut rock slopes resulting from quarrying or highway engineering abandoned in China because of immature outside soil spray seeding (OSSS) engineering techniques. To improve properties of synthetic soil technique to spray on such slopes (gradient >50°), four components of OSSS, that is, cement, inorganic compound fertilizers (ICF), wood bits, and peat soil at four treatment levels for each were mixed into soil using orthogonal array designs OA16 (45). Relationships of each of four components with plant biomass, soil physicochemical and microbial features were explored to determine optimal synthetic soil combinations for OSSS techniques. Significant differences in plant biomass, soil physicochemical properties and microbial activities among 16 different OSSS synthetic soils with different contents of four components were identified. Optimal combination of N10 with higher nutrients (added with 0.8% ICF, 1.5% cement, 1.5% peat soil, and 2.0% wood bits) and N13 with highest viscidity (added with 0.4% ICF, 2.0% cement, 1.5% peat soil, and 2.0% wood bits) than other combinations were obtained to be used in OSSS sprayed soils to reconstruct the bare high- and cut rock slope s, which was supported by results of cluster analysis. On the other hand, based on canonical correlation analysis, redundancy analysis, and discriminant analysis, soil physicochemical properties explained 56.41% of the soil microbial activities and the cement is the most influential factor on soil properties. Among all tested indicators, soil NH4-N, total P, pH, organic C, phenol oxidase, invertase, CM-cellulase, acid phosphatase, alkaline phosphatase, and basal respiration were more responsive to OSSS synthetic soils. Our results have documented improvement of soil physicochemical and microbial features of the OSSS soil under the condition of 2.0% cement content. [ABSTRACT FROM AUTHOR]

ABSTRACT myo-Inositol phosphate synthase (MIPS) is the key enzyme of myo-inositol synthesis, which is a central molecule required for cell metabolism and plant growth as a precursor to a large variety of compounds. A full-length fragment of MfMIPS1 cDNA was cloned from Medicago falcata that is more cold-tolerant than Medicago sativa. While MfMIPS1 transcript was induced in response to cold, dehydration and salt stress, MIPS transcript and myo-inositol were maintained longer and at a higher level in M. falcata than in M. sativa during cold acclimation at 5 °C. MfMIPS1 transcript was induced by hydrogen peroxide (H2O2) and nitric oxide (NO), but was not responsive to abscisic acid (ABA). Pharmacological experiments revealed that H2O2 and NO are involved in the regulation of MfMIPS1 expression by cold and dehydration, but not by salt. Overexpression of MfMIPS1 in tobacco increased the MIPS activity and levels of myo-inositol, galactinol and raffinose, resulting in enhanced resistance to chilling, drought and salt stresses in transgenic tobacco plants. It is suggested that MfMIPS1 is induced by diverse environmental factors and confers resistance to various abiotic stresses. [ABSTRACT FROM AUTHOR]