RESUMEN
The coordination between phytohormones regulation, stomatal behaviour (stomatal index and opening/closing) and gas exchange are potent determinants of plant survival under drought stress. However, we found a knowledge gap in the mechanism regulating the fine-tuning of these features during drought. In order to address this we evaluated gas exchange, stomatal behaviour and endogenous phytohormones content in two cotton varieties (LRA-5166 and NBRI-67) differing in drought sensitivity during water deficit conditions. Variety specific differences were recorded in net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (gs) with significantly less decrease in drought tolerant LRA-5166 than drought sensitive NBRI-67. The abscisic acid (ABA) accumulation was significantly increased in LRA-5166 while reduced in NBRI-67 under water deficit, which was accompanied by relatively less reduced 6-benzylaminopurine (6-BAP) level in LRA-5166 than NBRI-67.Thus, improved ABA/6-BAP ratio was observed in both the varieties of cotton. Critically, LRA- 5166 has reduced stomatal index, aperture size and significantly higher A and intrinsic water use efficiency (WUEi), thus higher drought tolerance than NBRI-67. Furthermore, we found that endogenous ABA predominantly maintains the stomatal behaviour and regulates its physiology either by antagonizing 6-BAP or alone to coordinate with water deficit signals. Overall, our findings describe a new insight as to how drought modulates endogenous ABA and 6-BAP homeostasis in cotton leaf and the mechanism of stomatal regulation by ABA and 6-BAP in cotton.
RESUMEN
Carbon isotope fractionation associated with the aerobic consumption of propane (C3) were determined using Rhodococcus rhodochrous MTCC 291 bacterial strain to estimate the amount of hydrocarbon oxidized using GC, fractionation of δ13C carbon isotopes of propane and CO2 using GC-C-IRMS and growth of bacteria by UV-Visible Spectrophotometer. The initial δ13C isotopic value of propane was -34 ‰ and after incubation the changes of the isotopic values have been determined on 6th, 10th, 14th, and 17th days. The propane isotopic fractionation value was found to be maximum of -38.0 ‰ with an average value of -36.5 ‰ and a standard deviation of -1.22 ‰. The initial δ13C isotopic value of CO2 was -19.601 ‰. The CO2 isotopic fractionation value was found to be maximum of -29.153 ‰ with an average value of -26.859 ‰ and a standard deviation of -28.338 ‰. The consumption of propane gas was estimated using Gas Chromatograph. The initial concentration of propane in control was found to be 53 ppm. On incubation, the consumption of the propane gas was observed to be of 26 ppm. The carbon isotope fractionation presented here may be applied to estimate the extent of C1-C4 oxidation in natural gas samples, and should prove useful in further studying the microbial oxidation of these compounds in the natural environment.
RESUMEN
Several techniques are used for the exploration of hydrocarbons, of which; the geochemical techniques involving the microbiological technique use the principle of detecting the light hydrocarbon seepage activities for indication of sub-surface petroleum accumulations. A survey was carried out to characterize the light gaseous hydrocarbons seeping in oil and gas fields of Krishna-Godavari basin of Andhra Pradesh. A set of 50 sub-soil samples were collected at depths of about 3 m for geochemical analyses and 1m for microbiological analysis. The microbial prospecting studies showed the presence of high bacterial population for methane 2.5 x 102 to 6.0 x 106 cfu g-1, propane 1x102 to 8.0 x 106 cfu g-1 in soil samples. The adsorbed soil gas analysis showed the presence of moderate to low concentrations of methane (26 to 139 ppb), ethane (0 to 17 ppb), propane (0 to 8 ppb), butane (0 to 5 ppb) and pentane (0 to 2 ppb) in the soil samples of the study area. Carbon isotope analysis for methane (´13C1) ranging from -36.6 to -22.7‰ Pee Dee Belemnite (PDB) suggests these gases are of thermogenic origin. Geo-microbial prospecting method coupled with adsorbed soil gas and carbon isotope ratio analysis have thus shown good correlation with existing oil/ gas fields of Krishna-Godavari basin.
RESUMEN
Water quality, the carbon isotope ratio of suspended particulate organic matter (POM), and limiting nutrients were investigated at seven surface and bottom seawater stations in Gamak Bay, South Korea, to evaluate the effectiveness of counter-measures to organic matter increase. The increase in surface water COD in Gamak Bay appear to be the result of phytoplankton growth, which is consistently limited by nitrogen (N) or phosphorous (P), but not by silicon (Si). High chlorophyll a concentrations seem to be caused by freshwater inputs of N and P associated with wastewater in the northern and northeastern portions of the Bay, and by the inflow of NH4-N and P associated with the digestion of organic matter from the bottom layer in western areas. To regulate the increase of organic matter in Gamak Bay, controlling phytoplankton growth, particularly by regulating the input of N or P, may be more important than controlling the input of terrestrial organic matter.
RESUMEN
Isotopic, biogeochemical and ecological structure can provide a new dimension for understanding material flows, and the simultaneous function and structure of an ecosystem. Distributions of δ13C and δ15N for biogenic substances in the Nanakita river estuary involving Gamo lagoon in Japan were investigated to construct isotope biogeochemical and ecological structure for assessing fate and transfer of organic matter, and food web structure. The isotopic framework of the ecosystem was successfully described in a δ15N–δ13C map. In this estuary the variations of isotope ratios of biogenic substances were clearly explained by the mixing of land-derived organic matter, and marine-derived organic matter. A trophic-level effect of 15N enrichment was clearly observed. Organisms were classified into three groups depending upon the contribution of land-derived organic matter in a food chain. Almost all biota except mollusca in the lagoon depend on organic matter of marine origin. The contributions of both land and marine organic matter were comparable for mollusca in the lagoon.