Impact of biofertilisers on iron homeostasis and grain quality in the rice variety Uma under Elevated CO2.

The diminishing nutritional quality of rice with increasing concentrations of atmospheric CO2 is currently a major global concern. The present study was designed with the objective of assessing the impact of biofertilisers on grain quality and iron homeostasis in rice under elevated CO2. A completely randomised design with four treatments ([KAU, POP (control), POP+Azolla, POP+PGPR, and POP+AMF]), each replicated three times under ambient and elevated CO2 conditions, was followed. The analysed data revealed that yield, grain quality, and iron uptake and translocation were modified in an unfavourable manner under elevated CO2, which was reflected in the lower quality and iron content of the grains. The response of iron homeostasis in the experimental plants to the application of biofertilisers, especially plant-growth-promoting rhizobacteria (PGPR), under elevated CO2 strongly suggests the possibility of utilising them for designing iron management strategies for achieving higher quality in rice.

Improved transformation of Agrobacterium assisted by silver nanoparticles.

In transgenic plant development, the low transformation efficiency of Agrobacterium with exogenous DNA is the major constraint, and hence, methods to improve its transformation efficiency are needed. Recently, nanoparticlemediated gene transfer has evolved as a key transformational tool in genetic transformation. Since silver nanoparticles (AgNPs) can induce pores on the cell membrane, their efficacy in the improvement of conventional calcium chloride freeze-thaw technique of transformation of Agrobacterium was explored in this study. Agrobacterium cells in the exponential growth phase were exposed to different concentrations of AgNPs (0.01, 1, 5, 10, and 20 mg/l), and the half-maximal effective concentration (EC50) was determined via Probit analysis using the SPSS software. Transformation efficiency of AgNPs alone and in combination with calcium chloride was compared with that of the conventional calcium chloride freeze-thaw technique. AgNPs at a concentration of 0.01 mg/l in combination with calcium chloride (20 mM) showed a ten fold increase in the transformation efficiency (3.33 log CFU (colony-forming unit/microgram of DNA) of Agrobacterium tumefaciens strain EHA 105 with plasmid vector pART27 compared with the conventional technique (2.31 log CFU/µg of DNA). This study indicates that AgNPs of size 100 nm can eliminate the freeze-thaw stage in the conventional Agrobacterium transformation technique, with a 44% improvement in efficiency. The use of AgNPs (0.01 mg/l) along with 20 mM calcium chloride was found to be an economically viable method to improve the transformation of Agrobacterium with exogenous plasmid DNA.

Silver nanoparticles for biolistic transformation in Nicotiana tabacum L.

The present study reports the use of silver nanoparticles as a gene carrier, substituting gold microcarrier for biolistic gene delivery in Nicotiana tabacum L. Efficiency of biolistic transformation using silver nanoparticles (100 nm) was compared with that of gold microcarriers (0.6 micron) under varying helium pressure (450 psi, 650 psi, 900 psi and 1100 psi) and target distance (6 cm and 9 cm). Among the different concentrations (0.01-100 mgL-1) of silver nanoparticles tried, 10 mgL-1 produced the highest number of transient GUS expression (30) with statistical significance. Helium pressure of 650 and target distance of 9 cm, and 900 psi pressure and 6 cm distance resulted in the highest GUS expression with gold microcarriers and silver nanoparticles, respectively. Transformation efficiency was significantly higher with silver nanoparticles than gold microparticles as carriers resulting in a reduction up to 37.5-fold on the cost of consumables. Regeneration efficiencies of tissues bombarded with gold microcarriers and silver nanoparticles were 62.5% and 70.83%, respectively.

High temperature induced changes in quality and yield parameters of tomato (Solanum lycopersicum L.) and similarity coefficients among genotypes using SSR markers.

High temperature induced by climatic fluctuations are an important threat for plant growth, development and quality of agricultural produces. Adaptableness to environmental changes generally derives from a large set of genetic traits affecting physio-morphological, biochemical and agronomic parameters. Therefore, the identification of genotypes with higher yield and good quality parameters at high temperatures is becoming increasingly necessary for future breeding programs. Here, we analyzed the performance of different tomato genotypes grown under elevated temperatures in terms of yield and nutritional quality of the fruit. High temperature stress was induced from flower initiation to maturity stage by keeping the pots in a temperature controlled green house facility for 45 days. The quality and yield parameters were taken at the harvesting stage. Starch and soluble sugar concentration in the leaves of tomato genotypes showed significant reduction in its amount under heat stress. Titrable acidity (TA), total soluble solids (TSS) and ascorbic acid content of tomato fruits were highest under high temperature conditions compared to ambient condition but lycopene content decreased with rise in temperature. The yield attributes viz., number of fruits/plant, fruit set %, average fruit weight (g), yield per plant (g/plant) were significantly lower for Arka Saurabh, Arka Rakshak and Pusa Rohini when compared to other genotypes under study. Molecular characterization of selected 22 tomato genotypes were assessed using 25 simple sequence repeat (SSR) markers. Phylogenetic tree was constructed by the unweighted neighbour-joining method (UPGMA) using NTSYSpc cluster analysis software. The Jaccard's similarity matrix was constructed using the SIMQUAL method using UPGMA algorithm in NTSYSpc. Jaccard's similarity matrix among these tomato genotypes ranged from a minimum of 0.22 to a maximum of 1 with an average genetic similarity of 0.67. Hence this study has importance in identifying genotypes that could maintain good quality and higher yield under high temperature condition.

Water stress mediated root trait dynamics and identification of microsatellite markers associated with root traits in rice (Oryza sativa L.).

To identify microsatellite markers associated with root traits for drought tolerance in rice (Oryza sativa L.) a study was conducted at Department of Plant Physiology, College of Agriculture, Trivandrum, Kerala Agricultural University. A set of thirty-five rice genotypes were exposed to water stress and evaluated for physio-morphological components as indices of water stress tolerance. Observations were made on leaf rolling score and root traits, especially the root length, root dry weight, root volume and root shoot ratio at booting stage. As of the data obtained, ten tolerant and ten susceptible varieties were selected for bulk line analysis to identify the DNA markers linked with target gene conferring drought tolerance. Out of 150 SSR primers screened, RM474 showed polymorphism between the tolerant and susceptible bulks. Individual genotypes of the bulks also showed the same product size of the respective tolerant and susceptible bulks.

A novel approach for increasing transformation efficiency in E. coli DH5α cells using silver nanoparticles.

The present study is the first report on the application of silver nanoparticles for efficient bacterial transformation. EC50 value of 100 nm silver nanoparticles against E. coli DH5α cells was recorded as 4.49 mg L-1 in toxicity assay. Competency induction in E. coli DH5α cells by treatment with 100 nm silver nanoparticles at a concentration of 1 mg L-1 for 60 min and transformation using three plasmid vectors of different sizes, viz. pUC18, pBR322 and pCAMBIA resulted in tenfold increase in the bacterial transformation efficiency, i.e. 8.3 × 104, 8.0 × 104 and 7.9 × 104 cfu ng-1 of DNA, respectively, even without heat shock compared to the conventional chemical method using 0.1 M calcium chloride (2.3 × 103 cfu ng-1 of DNA).

Calcium alginate encapsulated synthetic seed production in Plumbago rosea L. for germplasm exchange and distribution.

Plumbago rosea L. (Plumbaginaceae), is a medicinal shrub commercially exploited for its naphthoquinone principle, plumbagin, extracted from the roots especially for treating skin disorders. As the plant is exploited from the wild without being replenished, conservation of the species becomes inevitable. Synthetic seeds would provide for effective conservation, germplasm exchange and distribution of this species. A reliable protocol for synthetic seed production in Plumbago rosea has been developed encapsulating the axillary buds. The axillary buds from P. rosea cultures established and multiplied using the nodal explants in Murashige and Skoog (MS) medium supplemented with Benzyl Adenine (BA) 1.5 mg/L and Indole 3-Acetic acid 1.0 mg/L, were used for synseed production. The plantlet conversion efficiency was the highest in synthetic seeds developed with sodium alginate 2.5% in modified MS with 0.4 M sucrose and CaCl2 100 mM. This combination gave the earliest bud initiation (9.19 ± 0.39 days) and maximum number of shoots per explant (2.31 ± 0.16 shoots). Microshoots from the culture, when inoculated on to MS medium supplemented with Naphthalene Acetic Acid 1.0 mg/L gave the best rooting response with 10.67 ± 0.94 roots per plant and 5.42 ± 0.29 cm root length. This is the first report of synthetic seed production in P. rosea using axillary buds as explant.

Anti-ulcer activity of Ficus religiosa leaf ethanolic extract.

OBJECTIVE: To evaluate the anti-ulcer activity and acute toxicity of Ficus religiosa (F. religiosa) leaf ethanolic extract in animal models. METHODS: Anti-ulcer activity of F. religiosa ethanolic extract (250 and 500 mg/kg body weight) was studied on stress induced ulcer animal models. Ranitidine was used as standard. The anti-ulcer activity of F. religiosa was evaluated with the help of ulcer area and histopatholgical examination. Preliminary phyto-chemical screening and acute toxicity studies of F. religiosa also carried out. RESULTS: Results showed that the extract treatments prevented ulcer area and gastric secretion in a dose-dependent manner. Administration of 2 000 mg/kg extract did not show any acute toxicity in albino mice. Preliminary phytochemical analysis identified the presence of flavonoids in the ethanolic extract of F. religiosa. CONCLUSIONS: The extract is non-toxic even at relatively high concentrations. The anti-ulcer activity is probably due to the presence of flavanoids.

Evaluation of the mutagenic potential and acute oral toxicity of standardized extract of Ocimum sanctum (OciBest™).

Ocimum sanctum L. (Lamiaceae) is found throughout India and in many parts of world. O. sanctum is used for the treatment of various health indications. In this lieu, it is of prime importance to investigate the safety aspects of the plant. Hence, the present study was conducted to investigate the possible genotoxic potential and acute oral toxicity of the extract of O. sanctum (OciBest™). The standard battery of in vitro genotoxicity tests, namely bacterial reverse mutation, chromosome aberration and micronucleus (MN) tests were employed to assess the possible mutagenic activity. The results showed that OciBest™ (7.9-2500.0 µg/mL) did not increase the number of histidine revertant colonies in Salmonella typhimurium strains (TA98 and TAMix) with and without exogenous metabolic activation (S9). OciBest™ (10.0-100.0 µg/mL) did not show structural chromosomal aberrations or increase in MN induction, with and without S9, at the tested dose range in both 4-h and 18-h exposure cell cultures. Thus, OciBest™ is not genotoxic in bacterial reverse mutation, chromosomal aberration and MN tests. In an acute oral toxicity test, rats were treated with 5 g/kg of OciBest™ and observed for signs of toxicity for 14 days and the results did not show any treatment-related toxic effects to Wistar rats.