Munna Singh

Expression of protein complexes and individual proteins upon transition of etioplasts to chloroplasts in pea (Pisum sativum)

The protein complexes of pea (Pisum sativum L.) etioplasts, etio-chloroplasts and chloroplasts were examined using 2D Blue Native/SDS-PAGE. The most prominent protein complexes in etioplasts were the ATPase and the Clp and FtsH protease complexes which probably have a crucial role in the biogenesis of etioplasts and chloroplasts. Also the cytochrome b(6)f (Cyt b(6)f) complex was assembled in the etioplast membrane, as well as Rubisco, at least partially, in the stroma. These complexes are composed of proteins encoded by both the plastid and nuclear genomes, indicating that a functional cross-talk exists between pea etioplasts and the nucleus. In contrast, the proteins and protein complexes that bind chlorophyll, with the PetD subunit and the entire Cyt b(6)f complex as an exception, did not accumulate in etioplasts. Nevertheless, some PSII core components such as PsbE and the luminal oxygen-evolvong complex (OEC) proteins PsbO and PsbP accumulated efficiently in etioplasts. After 6 h de-etiolation, a complete PSII core complex appeared with 40% of the maximal photochemical efficiency, but a fully functional PSII was recorded only after 24 h illumination. Similarly, the core complex of PSI was assembled after 6 h illumination, whereas the PSI-light-harvesting complex I was stably assembled only in chloroplasts illuminated for 24 h. Moreover, a battery of proteins responsible for defense against oxidative stress accumulated particularly in etioplasts, including the stromal and thylakoidal forms of ascorbate peroxidase, glutathione reductase and PsbS.

Expression in Arabidopsis and cellular localization reveal involvement of rice NRAMP, OsNRAMP1, in arsenic transport and tolerance

Irrigation of paddy fields to arsenic (As) containing groundwater leads to As accumulation in rice grains and causes serious health risk to the people worldwide. To reduce As intake via consumption of contaminated rice grain, identification of the mechanisms for As accumulation and detoxification in rice is a prerequisite. Herein, we report involvement of a member of rice NRAMP (Natural Resistance-Associated Macrophage Protein) transporter, OsNRAMP1, in As, in addition to cadmium (Cd), accumulation through expression in yeast and Arabidopsis. Expression of OsNRAMP1 in yeast mutant (fet3fet4) rescued iron (Fe) uptake and exhibited enhanced accumulation of As and Cd. Expression of OsNRAMP1 in Arabidopsis provided tolerance with enhanced As and Cd accumulation in root and shoot. Cellular localization revealed that OsNRAMP1 resides on plasma membrane of endodermis and pericycle cells and may assist in xylem loading for root to shoot mobilization. This is the first report demonstrating role of NRAMP in xylem mediated loading and enhanced accumulation of As and Cd in plants. We propose that genetic modification of OsNRAMP1 in rice might be helpful in developing rice with low As and Cd content in grain and minimize the risk of food chain contamination to these toxic metals.

Expression of OsMATE1 and OsMATE2 alters development, stress responses and pathogen susceptibility in Arabidopsis

Multidrug and Toxic compound Extrusion proteins (MATE) are a group of secondary active transporters with ubiquitous occurrences in all domains of life. This is a newly characterized transporter family with limited functional knowledge in plants. In this study, we functionally characterised two members of rice MATE gene family, OsMATE1 and OsMATE2 through expression in heterologous system, Arabidopsis. Expression of OsMATEs in Arabidopsis altered growth and morphology of transgenic plants. Genome-wide expression analysis revealed modulation of genes involved in plant growth, development and biotic stress in transgenic lines. Transgenic plants displayed sensitivity for biotic and abiotic stresses. Elevated pathogen susceptibility of transgenic lines was correlated with reduced expressions of defence related genes. Promoter and cellular localization studies suggest that both MATEs express in developing and reproductive organs and are plasma-membrane localised. Our results reveal that OsMATE1 and OsMATE2 regulate plant growth and development as well as negatively affect disease resistance.

Role of micronutrients on quantitative traits and prospects of its accumulation in linseed (Linum usitatissimum L.)

The adequate growth of plants can be achieved only by a balanced ratio of biologically active nutrients in soil along with its readily availability. Linseed seems to be an advantageous secondary oilseed crop widely used in industrial purposes, which can serve additional purpose of phytoextraction of heavily infested soils with heavy metals. In this study, we have made an effort to find out the optimum dose of heavy metals necessary as micronutrients like copper (Cu), iron (Fe) and zinc (Zn) for the enhancement of linseed yield along with the distribution of heavy metals in different plant parts. Quantitative enhancement in different traits of linseed plant due to Cu, Fe and Zn fertilization especially for capsules per plant after maturity suggested positive association between heavy metal supply and morphological traits, which indirectly enhanced seed yield. There was a positive correlation between Zn supply and seed yield. In the treatments with Cu and Fe fertilization, seed yield was positively correlated to plant height, capsules per plant and seeds per five capsules. According to this study, it is concluded that linseed has the ability to accumulate majorly Fe followed by Cu and Zn.

Developing a mathematical model for variation of physiological responses of Jatropha curcas leaves depending on leaf positions under soil flooding

The effect of soil flooding on photosynthesis, transpiration and stomatal conductance of Jatropha curcas seedlings were studied under natural environmental variables. Soil flooding reduced photosynthesis (PN), transpiration (E) and stomatal conductance (gs) in response to leaf positions of Jatropha curcas plants. Based on the results, we conclude that decrease in stomatal opening and stomatal limitation of photosynthesis, followed by decrease in individual leaf area are the main causes of reductions in carbon uptake of flooded seedlings. A mathematical relationship was successfully developed to describe photosynthesis, transpiration and stomatal response of Jatropha under soil flooding stress.

Application of distillery spent wash and its effect on sucrose content in sugarcane

Effect of distillery spent wash (DSW) was studied on plant and ratoon crop of on three sugarcane (Saccharum spp. hybrids) genotypesviz, CoS 95255 (early maturing and high sugar), CoS 767 (mid-late and medium sugar) and BO91 (late maturing and medium sugar). The DSW was applied through irrigation water during early growth stage (60 and 90 DAP) at three different concentrations,viz. 25,50 and 100 %. In control plants, normal irrigation was given. The effect of different concentrations of DSW was observed on the Brix and sucrose profile in cane juice during the whole crop cycle (from 180 to 330 days after treatment). The suitability of different genotypes for different concentrations of DSW was also observed. The study revealed that all cane varieties showed improvement in total soluble solids (TSS %) by addition of 25% DSW, but showed negative response at higher doses. Early maturing variety (CoS 95255) showed greater accumulation during winter months as compared to late maturing variety (BO 91). Application of vinasse @ 25% concentration showed marked improvement in sucrose accumulation in all the three varieties and this trend was recorded till harvest. The ratoon crop showed almost similar trend, indicating that vinasse application elicited same physiological response in plant as well as ratoon crops of sugarcane. Variety CoS 95255 was found to be best suited for the application of DSW @ 25% concentration.

Phytotoxicity of Fluoride in Guar (Cyamopsis tetragonoloba) Cultivars and its Effect on Morpho-Physiological and Biochemical Traits

This study reports the influence of 0 (1.42), 25, 50, 100, 200 and 400ppm (artificial contaminated water) fluoride on guar (Cyamopsis tetragonoloba L. cultivar local and sadabahar). Seedlings showed decrease in the following morphophysiological and biochemical characteristics: growth, leaf area expansion, SPAD value, chlorophyll fluorescence, yield and antioxidant enzymes, i.e. catalase, peroxidase and superoxide dismutase. At 400ppm F-contaminated irrigation water the average leaf area expansion (∼58 and 45%), shoot-root length (∼45, 46% (local) and ∼23, 54% (sadabahar), SPAD value (∼11, 25, 18% (local) and ∼12, 20, 15% (sadabahar), Fv/Fm (∼8, 11, 16% (local) and ∼6, 9, 12% (sadabahar), catalase (∼21 and 16%), peroxidise (∼42 and 38%) and SOD (∼40 and 39%) in local and sadabahar cultivar, respectively. With increasing F concentrations, growth, physiological and enzyme activity were successively reduced with days and duration of treatment frequency.

Fluoride Inhibits Root Water Transport and Affects Morpho-Physio-Biochemical Characteristics in Guar (Cyamopsis tetragonoloba)

This study focuses on the fluoride contaminated irrigation water on guar (Cyamopsis tetragonoloba) plants to investigate establishment of growth, development and physio-biochemical activity associated with yield characteristics. Long-term fluoride irrigation influence was also recorded using 15-days old established seedlings raised in earthen pots. These fully established guar plants irrigated differentially by using fluoride contaminated water i.e. 1.42 (without contamination of F), 4.02 (Unnao district, naturally contaminated water), 25, 50, 100, 200 & 400 ppm (artificially contaminated water) applied in pots. The fluoride irrigation frequency n=6 (weekly) was maintained and afterwards terminated/harvested. The results showed reduction in morpho-physiological characteristics in relation to without contaminated water (1.42 ppm) of fluoride in both cultivars i.e. HG2–20 and RGC-936. Similar trends were found in enzymatic activity such as catalase, peroxidase and superoxide dismutase in fluoride contaminated irrigation water. The higher loss was observed in 400ppmF as compared to 25, 50, 100 and 200ppm of fluoride contaminated water in both cultivars.