Characterization of a plant-growth-promoting non-nodulating endophytic bacterium (Stenotrophomonas maltophilia) from the root nodules of Mucuna utilis var. capitata L. (Safed Kaunch).

Nonrhizobial root nodule endophytic bacteria are known to have beneficial effects on host plants and are also considered contaminants or opportunists. They grow either individually or as a co-occupant of the root nodules of legumes. In this study, a nonrhizobial endophytic bacterial strain was isolated from the root nodules of the medicinal legume Mucuna utilis var. capitata L.; phenotypic, genotypic, and agricultural characterization was performed using a HiMedia kit and 16S rRNA sequencing. This strain showed tremendous seedling growth potential (30%), compared with the control, as well as a strong antagonistic nature against the plant pathogenic fungus Fusarium udum when plant growth parameters were analyzed. The strain, identified by 16S rRNA as Stenotrophomonas maltophilia, showed a multitude of plant-growth-promoting attributes both direct (IAA, phosphate solubilization) and indirect (ACC deaminase, siderophore) and enhanced the growth of host plant in field trials. This is the first report of the plant-growth-promoting potential of this endophytic bacterium from the nodules of M. utilis var. capitata L.; hence, it has potential for use in various biotechnological applications in various industries.

Weed Dynamics during Transition to Conservation Agriculture in Western Kenya Maize Production.

Weed competition is a significant problem in maize (Zea mays, L.) production in Sub-Saharan Africa. Better understanding of weed management and costs in maize intercropped with beans (Phaseolus vulgaris, L.) during transition to conservation agricultural systems is needed. Changes in weed population and maize growth were assessed for a period of three years at Bungoma where crops are grown twice per year and at Trans-Nzoia where crops are grown once per year. Treatments included three tillage practices: minimum (MT), no-till (NT) and conventional (CT) applied to three cropping systems: continuous maize/bean intercropping (TYPICAL), maize/bean intercropping with relayed mucuna after bean harvest (RELAY) and maize, bean and mucuna planted in a strip intercropping arrangement (STRIP). Herbicides were used in NT, shallow hand hoeing and herbicides were used in MT and deep hoeing with no herbicides were used in CT. Weed and maize performance in the maize phase of each cropping system were assessed at both locations and costs of weed control were estimated at Manor House only. Weed density of grass and forb species declined significantly under MT and NT at Manor House and of grass species only at Mabanga. The greatest declines of more than 50% were observed as early as within one year of the transition to MT and NT in STRIP and TYPICAL cropping systems at Manor House. Transitioning to conservation based systems resulted in a decline of four out of five most dominant weed species. At the same time, no negative impact of MT or NT on maize growth was observed. Corresponding costs of weed management were reduced by $148.40 ha(-1) in MT and $149.60 ha(-1) in NT compared with CT. In conclusion, farmers can benefit from effective and less expensive weed management alternatives early in the process of transitioning to reduced tillage operations.

Innovative use of Mucuna monosperma (Wight) callus cultures for continuous production of melanin by using statistically optimized biotransformation medium.

Melanins are predominantly indolic polymers which are having extensive applications in cosmetics, agriculture and medicine. In the present study, optimization of nutritional parameters influencing melanin production by Mucuna monosperma callus cultures was attempted using the response surface methodology (RSM). Standardization of four factors was carried out using the Box-Behnken design. The optimized levels of factors predicted by the model include tyrosine 0.978gL(-1), pH 5.85, SDS 34.55mgL(-1)and copper sulphate 21.14mgL(-1) tyrosine, which resulted in highest melanin yield of 0.887gL(-1). The optimization of medium using RSM resulted in a 3.06-fold increase in the yield of melanin. The ANOVA analysis showed a significant R(2)-value (0.9995), model F-value (1917.72) and probability (0.0001), with insignificant lack of fit. Optimized medium was used in the laboratory scale column reactor for the continuous production of melanin. Uninterrupted flow column exhibited maximum melanin production rate of 250mgL(-1)h(-1) which is the highest value ever reported using plant as a biotransformation source. Melanin production was confirmed by spectrophotometric and chemical analysis. Thus, this study demonstrates the production of melanin by M. monosperma callus, using a laboratory scale column reactor.

Practical use of CMC-amended rhizobial inoculant for Mucuna pruriens cultivation to enhance the growth and protection against Macrophomina phaseolina.

In many parts of the world Mucuna pruriens is used as an important medicinal, forage and green manure crop. In the present investigation the effect of the addition of CMC in carrier during development of bioformulation on shelflife, plant growth promotive and biocontrol activity against Macrophomina phaseolina was screened taking M. pruriens as a test crop. Ensifer meliloti RMP6(Ery+Kan+) and Bradyrhizobium sp. BMP7(Tet+Kan+) (kanamycin resistance engineered by Tn5 transposon mutagenesis) used in the study showed production of siderophore, IAA, solubilizing phosphate and biocontrol of M. phaseolina. RMP6(Ery+Kan+) also showed ACC deaminase activity. The survival of both the strains in sawdust-based bioformulation was enhanced with an increase in the concentration of CMC from 0 to 1%. At 0% CMC Bradyrhizobium sp. BMP7(Tet+Kan+) showed more increase in nodule number/plant (500.00%) than E. meliloti RMP6(Ery+Kan+) (52.38%), over the control in M. phaseolina-infested soil. There was 185.94% and 59.52% enhancement in nodule number/plant by RMP6(Ery+Kan+) and BMP7(Tet+Kan+) with an increase in the concentration of CMC from 0% to 1% in the bioformulations. However further increase in concentration of CMC did not result in enhancement in survival of either the strains or nodule number/plant.

[Study on quality standard of Mucuna pruriens var. utilis].

OBJECTIVE: To provide scientific basis for the utilization and development of Mucuna pruriens var. utilis by establishing its quality control standard. METHODS: The bioactive constituents were analyzed by TLC and HPLC. Moisture, ash and the extracts of Mucuna pruriens var. utilis were all determined. RESULTS: The TLC spots of levodopa had similar color with the control group at the same position. The results of HPLC quantitative analysis showed that the linear range of levodopa was 26.45 to approximately 132.25 microg/mL, r = 0.9992, and the average recovery rate was 103.8%, RSD = 1.85%. CONCLUSIONS: This method is convenient, accurate, reliable with good reproducibility, so it can be used to establish quality standard for the medicinal material.

Distribution of L-DOPA in the root of velvet bean plant (Mucuna pruriens L.) and gravity.

Velvet bean (Mucuna pruriens L.) has been found that the degree of suppression on the lettuce root growth by velvet bean was less on the 3D-clinorotation. The number and growth of adventitious root in velvet bean differed among the clinostated and control group. L-DOPA (L-3,4-dihydroxyphenylalanine) is known to be the major substance in the allelopathy of velvet bean plant, released from its root. Since L-DOPA is a precursor of melanin pigment, and is easily converted to melanin by oxidation, locality of L-DOPA production in the plant body can be seen through pigmentation. The amount of L-DOPA was analyzed by HPLC and LC-ESI/MS. The distribution of L-DOPA in the root was different among the ground control condition and pseudo-microgravity.

Volatile allelopathy in velvet bean (Mucuna pruriens [correction of pruiens] L.) and gravity.

Allelopathy caused by volatile compounds was studied with velvet bean (Mucuna pruriens [correction of prueiens] L.). Preparatory experiment was conducted to identify the relationship between action of volatiles and gravity. The experimental protocol was defined and tested to study on volatile allelopathy of velvet bean. Root growth of lettuce (Lactuca sativa L.) seedlings was inhibited by volatile gas from velvet bean seedlings planted in Agripot. In this study, it was shown that ten-day velvet bean seedling could exhibit the volatile allelopathic ability. Growth chambers for volatile experiment were designed. Velvet bean seed can germinate in a 3-ml small vial.

Reduced allelopathic inhibition of lettuce (Lactuca sativa) growth caused by velvet bean (Mucuna pruriens) under 3D-clinorotation.

Allelopathy between Mucuna pruriens (velvet bean) and Lactuca sativa (lettuce) was studied under 3D-clinorotation. Growth of both roots and shoots of lettuce seedlings was suppressed by the presence of velvet bean. The degree of suppression was less on the clinostat compared to the normal static earth gravity. L-DOPA (L-3, 4-dihydroxyphenylalanine) is known to be a major substance in allelopathy of velvet bean. Amount of L-DOPA diffused out from a sintered filter paper into agar medium was compared between clinorotation and control group, and found no significant difference. It was concluded that some factors related to release, transport, and sensing phenomena of allelopathic substances may be responsible to the new findings in this study.

[Research plan to study allelopathy under microgravity].

Living organisms interact each others and form ecological system on the earth. Such interactions between organisms and species have been long known, and studied at a global scale. Allelopathy is a phenomenon observed in many plants that emit specific chemicals acting on other organisms, including animals and microorganisms, in either inhibitory or excitatory ways. We propose to study whether phenomena of allelopathy are modified under altered gravity or not. If biosynthesis, emission and sensing mechanism of allelopathic substances would be affected by gravity, many organisms and ecological system might show different behaviors based on the inter-organisms and species interactions under microgravity. In the macroscopic scale, transport of the substances between organisms is largely affected by convection induced by gravity. Furthermore, the fate of allelopathic substances in confined environment differs from that seen on the earth, because of lacking sink compartment for removal and producing exotic bio-active substances by man-made system. We design basic ground experiment to evaluate gravitational effects on allelopathy applying pseudo-microgravity. Our study contributes to the synthesis of ecological system and its control on spacecrafts and extraterrestrial bodies. It also makes possible to sustain qualitative human life even on the ground under confined artificial environment that dominates in many scenes.