The effect of water deficit on nodulation, N2 fixation, photosynthesis, and total soluble sugars and leghemoglobin in nodules was investigated in cowpea and groundnut. Nitrogenase activity completely ceased in cowpea with a decrease in leaf water potential (
leaf) from –0.4 MPa to –0.9 MPa, while in groundnut it continued down to –1.7 MPa. With increasing water stress, the acetylene reduction activity (ARA) declined very sharply in cowpea, but ARA gradually decreased in groundnut. Even with mild water stress (
leaf of 0.2 MPa), nodule fresh weight declined 50% in cowpea partly due to a severe nodule shedding whereas nodule fresh weight declined in groundnut only when
leaf decreased by 1.0 MPa. No nodule shedding was noticed even at a higher stress level in groundnut. Photosynthesis and stomatal conductance were also more stable in groundnut than in cowpea under water stress. There was a sharp increase in total soluble sugars and leghemoglobin in the nodules of groundut with water stress, but no definite trend could be found in cowpea. 相似文献
Medicinal and aromatic plants possess pharmacological properties (antidiabetes, anticancer, antihypertension, anticardiovascular, antileprosy, etc.) because of their potential to synthesize a wide range of therapeutic bioactive secondary metabolites. The concentration of bioactive secondry metabolites depends on plant species, local environment, soil type and internal microbiome. The internal microbiome of medicinal plants plays the crucial role in the production of bioactive secondary metabolites, namely alkaloids, steroids, terpenoids, peptides, polyketones, flavonoids, quinols and phenols. In this review, the host specific secondry metabolites produced by endophytes, their therapeutic properties and host-endophytes interaction in relation to production of bioactive secondry metaboloites and the role of endophytes in enhancing the production of bioactive secondry metabolites is discussed. How biological nitrogen fixation, phosphorus solubilization, micronutrient uptake, phytohormone production, disease suppression, etc. can play a vital role in enhacing the plant growth and development.The role of endophytes in enhancing the plant growth and content of bioactive secondary metabolites in medicinal and aromatic plants in a sustainable mode is highlighted.
Laboratory evaluation of hyperthermophiles with the potential for Enhanced Oil Recovery (EOR) is often hampered by the difficulties in replicating the in situ growth conditions in the laboratory. In the present investigation, genome analysis was used to gain insights into the metabolic potential of a hyperthermophile to mobilize the residual oil from depleting high-temperature oil reservoirs. Here, we report the 1.9 Mb draft genome sequence of a hyperthermophilic anaerobic archaeon, Thermococcus sp. 101C5, with a GC content of 44%, isolated from a high-temperature oil reservoir of Gujarat, India. 101C5 possessed the genetic arsenal required for adaptation to harsh oil reservoir conditions, such as various heat shock proteins for thermo-adaptation, Trk potassium uptake system proteins for osmo-adaptation, and superoxide reductases against oxidative stress. Microbial Enhanced Oil Recovery (MEOR) potential of the strain was established by ascertaining the presence of genes encoding enzymes involved in the production of the metabolites such as hydrogen, bio-emulsifier, acetate, exopolysaccharide, etc. Production of these metabolites which pressurize the reservoir, emulsify the crude oil, lower the viscosity and reduce the drag, thus facilitating mobilization of the residual oil was experimentally confirmed. Also, the presence of crude oil degradative genes highlighted the ability of the strain to mobilize heavy residual oil, which was confirmed under simulated conditions in sand-pack studies. The obtained results demonstrated additional oil recoveries of 42.1% and 56.5% at 96 °C and 101 °C, respectively, by the strain 101C5, illustrating its potential for application in high-temperature oil reservoirs. To our best knowledge, this is the first report of genome analysis of any microbe assessed for its suitability for MEOR from the high-temperature oil reservoir.
We have investigated the correlation between the concentration of geranyl acetate (GA) and acetyl CoA: geraniol acetyltransferase
(GAAT) activity in palamarosa (Cymbopogon martini var. Motia) inflorescence and leaves at their different physiological stages. The results on GA concentration and the GAAT activity
have been expressed on per gram fresh weight, per spikelet pair or leaf and per unit area of the phylloplane also incase of
leaf. The percentage of geranyl acetate and geraniol in the volatile oil has also been considered. GA concentration was found
to be highest in unopened floral spikelets and on the decline in fully open spikelets matching the trend of GAAT activity.
Similarly, highest concentration of GA and maximum GAAT activity were found in leaves at mid-stage of development (stage II).
The regression analysis curve between GA concentration (mg gFw−1) and GAAT activity (IU 10−3 gFw−1) gave an estimate of correlation coefficient (at 95% confidence) value of 0.79 for flowers and 0.92 for leaf. The results
suggest that volatile ester (like geranyl acetate) synthesis in foliage and flowers of the aroma oil plant is controlled by
the existent catalytic levels GAAT rather than the availability of geraniol. The study also indicates that the GAAT to be
a good target to over-express for improvement of oil quality in terms of GA linked to fruit-fresh olfactory note of the oil. 相似文献