Veena Jain

Nitrate alters the flavonoid profile and nodulation in pea (Pisum sativum L.)

A rhizosphere application of NOinf3sup-and/or naringenin affected the Pisum sativum — Rhizobium leguminosarum biovar viciae symbiosis. NOinf3sup-(5 mM) lowered while naringenin raised the nodulation status (nodule numbers and weight) and nodule efficiency (C2H2 reduction activity). However, the inhibitory effect of NOinf3sup-was to some extent alleviated when applied in combination with naringenin. The plant biomass was increased by the application of NOinf3sup-and naringenin, either alone or in combination, while a higher root: shoot ratio was observed only in the naringenin-treated plants. Root flavonoids are known to regulate the expression of nod genes; their high-performance liquid chromatography profile was influenced in different ways by NOinf3sup-and naringenin.

Naringenin enhanced efficiency ofRhizobium meliloti-alfalfa symbiosis

Rhizobium meliloti-alfalfa (Medicago sativa) symbiosis was influenced by the rhizospheric application of naringenin which increased nodule number, nodule weight (2-to 8-fold) and nitrogenase activity. Plant blomass and total nitrogen content also increased by 60 to 72%. The enhancing effects of naringenin were more pronounced if it was applied at the early vegetative stage of plant growth or at the time of sowing.

Proline metabolism under water stress in the leaves and roots of Brassica juncea cultivars differing in drought tolerance.

Plant water relations, proline content and activities of pyrroline-5-carboxylate synthetase (P5CS) and proline oxidase (PO) were studied in five Brassica juncea genotypes differing in drought response. Under water stress, drought tolerant cv Varuna showed maximum osmotic adjustment value (1/b) of 3.21. In this variety, proline content increased from 8.4 and 5.3 μmol g−1 dry weight under normal conditions to 128.2 and 44.5 μmol g−1 dry weight under stress conditions in the leaves and roots respectively. The increase in proline content in less drought tolerant variety Prakash was from 7.0 and 1.8 μmol g−1 dry weight In the absence of stress to 62.9 and 13.4 μmol g−1 dry weight in the presence of stress in leaves and roots respectively. Compared to the respective controls, increase in the activity of proline biosynthetic enzyme P5CS of roots and leaves under water stress was maximum (∼ 94%) in Varuna and minimum in Prakash (∼16%). Reduction in the activity of proline degrading enzyme PO due to stress was also maximum in the leaves (75%) and roots (87%) of Varuna. These results showed genotype dependent effect of water stress on plant water relations and proline metabolism.

Effect of Low Temperature and Rh izospheric Application of Naringenin on Pea-Rhizobium leguminosarum biovar viciae Symbiosis

The production of Tsr factor by Rhizobium leguminosarum bv. viciae was influenced by low temperature (10°C) In the presence of seed exudate collected at 10°C and 25°C or naringenin (10fuM). Root exudate collected at 25°C and naringenin induced Tsr factor in R. leguminosarum causing thick and short root phenotype and root hair curling and deformation of host root. Root exudate collected at 10°C also induced root hair curling but Tsr activity was low. low temperature grown plants had poor nodulation, nitrogen fixation, nitrogen content and total blomass as compared to plants grown at 25°C. Rhizospheric application of naringenin partially alleviated the deleterious effect of low temperature on nodulation status and nodule efficiency.

Cobalt reduces nitrate inhibition of nodulation in mungbean (Vigna radiata).

Abstract A cobalt-mediated decrease in ethylene production reduced the inhibition of nodulation by nitrate in Vigna radiata (mungbean). Nitrate increased the ethylene production in 5-day-old seedlings, while it caused a reduction in the nodulation status (nodule number and nodule weight) and nodule efficiency (acetylene reduction activity) in mungbean plants. The application of cobalt chloride inhibited nitrate-affected ethylene production and also decreased the inhibitory effect of nitrate on nodulation. The effect of cobalt was most marked on nodule number.

Influence of Flavonoids on Nodulation and Carbon Partitioning in Pea-Rhizobium Symbiosis

Rhizospheric application of nod regulators influenced the nodulation status, nodule efficiency and partitioning of assimilated CO2 in Pisum sativum-Rhizobium leguminosarum symbiosis. Depending upon the plant growth stage, naringenin and flavone enhanced nodule number (22.8–87.6%), nodule weight (19.2–35.2%) and nitrogenase activity (17.8–108.6%). Syringaldehyde had negative effect on various parameters of symbiosis. Proportion of 14C-assimilates was higher in nodules of plants from naringenin and flavone treatments as compared to the control or syringaldehyde treatments. The enhanced nodule efficiency in naringenin and flavone treatments was reflected in the increased N content (12.7–50.4%) and biomass (4.3–35.1%) of plants.

Characterization of Low Molecular Weight Glutenin Subunit Gene Representing Glu-B3 Locus of Indian Wheat Variety NP4

Low molecular weight (LMW) glutenin subunits represent major part (30%) of storage proteins in wheat endosperm and determine the quality of dough. Despite their importance few LMW glutenin genes have been characterized so far and none from Indian wheat variety. In the present investigation PCR technique was employed to characterize LMW-GS gene representing Glu-B3 locus from Indian bread wheat cultivar NP4. The deduced protein sequence coded by Glu-B3 locus of LMW-GS gene from NP4 showed the presence of regular structure of the repetitive domain with varying numbers of glutamine (Q) residues and the presence of 1st cysteine residue within the repetitive domain at 40th position in mature polypeptide. Such structure might increase and stabilize the gluten polymer through intermolecular interactions of the large numbers of glutamine side chains and cysteine residues for intermolecular disulphide bond formation leading to stronger dough quality of NP4. Moreover, Glu-B3 specific primers could also be used for identifying 1BL/1RS translocation in addition to amplifying LMW glutenin genes. There was no amplification in 1B/1R translocation lines as short arm of wheat was replaced by short arm of rye chromosome in these lines. Such information can be useful in wheat improvement for dough properties for better chapati and bread quality.

Effect of Nitrate on Bradyrhizobium — Mungbean (Vigna radiata) Symbiosis in presence of Syringaldehyde

Bradyrhizoblum — mungbean (Vigna radiata) symbiosis was influenced by the application of nitrate in combination with.yrlngaldehyde. Application of nitrate alone at lower concentrations (2, 5 mM) caused a reduction at initial stage (10 DAS) while at later stage (35 DAS–45 DAS) enhanced the nodulation status (nodule number, nodule weight) and nodule efficiency (acetylene reduction activity). Higher concentration of nitrate (10 mM) caused a reduction in nodule number, nodule weight and acetylene reduction activity. Syringaldehyde alone improved the nodulation status and nodule efficiency while it acted synergistically when applied in combination with nitrate. These effects were also reflected in the biomass of plants.

Influence of Rhizosphere Application of Syringaldehyde on Rhizobia — Mungbean (Vigna radiata) Symbiosis

Summary The efficiency of mungbean (Vigna radiata) — rhizobia symbiosis was influenced by the rhizosphere application of syringaldehyde and naringenin. Syringaldehyde caused increase in nodule number (6–26%), nodule weight (9–36%) and nitrogenase activity (16–38%). Naringenin had an inhibitory effect on various parameters of symbiosis. There was increase in the plant biomass production by syringaldehyde treatment. These results open up a possibility of enhancement of biological nitrogen fixation by rhizosphere application of nod gene regulators.