Pradeep Kumar Shukla

Host-mediated gene silencing of a single effector gene from the potato pathogen Phytophthora infestans imparts partial resistance to late blight disease.

RNA interference (RNAi) has proved a powerful genetic tool for silencing genes in plants. Host-induced gene silencing of pathogen genes has provided a gene knockout strategy for a wide range of biotechnological applications. The RXLR effector Avr3a gene is largely responsible for virulence of oomycete plant pathogen Phytophthora infestans. In this study, we attempted to silence the Avr3a gene of P. infestans through RNAi technology. The P. infestans inoculation resulted in lower disease progression and a reduction in pathogen load, as demonstrated by disease scoring and quantification of pathogen biomass in terms of Pi08 repetitive elements, respectively. Transgenic plants induced moderate silencing of Avr3a, and the presence and/or expression of small interfering RNAs, as determined through Northern hybridization, indicated siRNA targeted against Avr3a conferred moderate resistance to P. infestans. The single effector gene did not provide complete resistance against P. infestans. Although the Avr3a effector gene could confer moderate resistance, for complete resistance, the cumulative effect of effector genes in addition to Avr3a needs to be considered. In this study, we demonstrated that host-induced RNAi is an effective strategy for functional genomics in oomycetes.

Uptake, Translocation, Accumulation, Transformation, and Generational Transmission of Nanoparticles in Plants

The field of plant nanotechnology has recently been up-surged into a new epoch of discovery to dissect the intricate processes and mechanisms for better understanding of plant’s functional biology in response to nanoparticle exposure. This chapter reviews the current scenario of pathways, mechanisms, and patterns of uptake, translocation, accumulation, transformation, and generational transmission of nanoparticles in plants. Experimental data support that symplastic route is the dominant and highly regulated pathway for transporting NPs within plants and facilitated by a vast array of carrier proteins, aquaporins, interconnected ion channels, endocytosed pathway, or novel pores for the entry of nanoparticles. Xylem being the most preferred plant tissue along with phloem and stomatal opening for absorption and transportation of nanoparticles. Engineered and carbon-based nanoparticles have shown different responses for their transport and utilization in different plants. Engineered nanomaterials are translocated and accumulated differentially within stems, leaves, trichomes, petioles, and fruits of different plants. At subcellular locations, engineered nanomaterials are accumulated in cell walls, cytoplasm, seldom plastids, nuclei, and small vesicles. Carbon-based nanomaterials have shown superior prospective for internalization. Uptake, accumulation, and generational transmission of NOM-suspended carbon nanopartcles in rice plants have been reported. Uptake and biodistribution of fullerol was confirmed almost in all plant organs including petioles, leaves, flowers, and fruits in bitter melon. Carbon nanotubes have shown the possibilities for effective penetration into seed coat. Single-walled carbon nanotubes have shown their capability to penetrate chloroplasts and accumulate on thylakoids and stroma in spinach, whereas, multi-walled carbon nanotubes were observed in the seeds and root systems of the developed tomato seedlings. It is certain that not a single transportation mechanism, but a diverse array of multiple mechanisms at physiological, biochemical, and molecular levels are involved for penetration, acquisition, and in planta trafficking of nanoparticles. The goal of this chapter is to put individual experimental efforts back together to unveil the possible enigmas of mechanisms of internalization of nanoparticles, pathways of their movement, and patterns of accumulation and their generational transmission.

Nanotechnology for Crop Improvement

Nanotechnology has the potential to reinforce the mission toward evergreen revolution by enhancing agricultural productivity with limited inputs. It is emerging as a paradigm shift and evolving as a promising tool to begin a new era of precise farming techniques and therefore may provide a possible solution for crop improvement, even in challenging environments. Employment of engineered nanoparticles (ENPs), whether carbon- or metal-based, may be the future solution to increase crop production for feeding the fast-growing world population. This chapter provides an overview of the current knowledge on the effects of nanoparticles for crop improvement. Overriding influences of different carbon, metal-based and metal oxide nanoparticles on different growth parameters (number of seminal root initiation, root elongation, shoot length, number of seeds, flowers and its quality), ultimately leading to increased plant biomass and yield have been presented. Throughout this chapter, the beneficial role of nanoparticles through enhanced seed germination, increased root and shoot length, fruit and crop yield, and substantial increase in vegetative biomass of seedlings and plants in many crops including maize, wheat, alfalfa, soybean, mustard, mung bean, tomato, potato, lettuce, spinach, onion, peanut, borage, Arabidopsis, cluster bean, and bitter melon is highlighted. The experimental evidences for enhancement of secondary metabolites through nanoparticle treatment under in vivo and in vitro conditions are presented. Although implementation of nanotechnology for agriculture sustainability via enhanced yield, biomass, and secondary metabolite is at juvenile stage, world will witness exceptional and unparalleled prospective of nanoparticles for invigorating agriculture in many ways. It is evident that more investigations are urgently required to know the type of nanoparticle, size, concentration, and mode of application to enable its application on large scale for crop improvement.

PCR Based Detection of Phytoplasma Association in Pot Marigold ( Calendula officinalis L.) and Guldawari ( Dendranthema grandiflora L.)

Flowering plants Calendula officinalis with phyllody and virescence and Dendranthema grandiflora with little leaf and formation of bladder like silique symptoms observed in Uttar Pradesh, India. The presence of phytoplasmas in diseased plants was detected by direct and nested polymerase chain reaction assays using phytoplasma-specific primer pairs P1/P7 and R16F2n/R2. In both flowering plants presence of phytoplasma was confirmed by amplification of 1200 bp product of phytoplasma 16S rRNA region with nested primer R16F2n/R2. This is the first report of phytoplasma associated with Calendula officinalis from India.

Green Synthesis of Silver Nanoparticles

The chemistry of the Earth is unimaginably complex mostly due to a splendid tangled web of interdependencies of living and lifeless components that include a vast, diverse, and global array of naturally occurring nanomaterials. Green synthesis of nanoparticles using biological entities is a novel, reliable, ecofriendly approach. So these can be used as mini factories for the production of nanoparticles. The green synthesis methods are more ecofriendly and safe compared to other physical and chemical methods. This chapter highlights a comprehensive view to understand the synthesis of silver nanoparticles.

Effect of Copper Oxide Nanoparticle on the Germination, Growth and Chlorophyll in Soybean (Glycine max (L.)

Agriculture is the backbone of most developing countries and it provides food for humans, directly and indirectly. Agricultural practices are catching public attention globally because climate change, energy and resource constraints, and rapidly growing global population are constantly increasing pressure on food and water resources. The use of nanoparticles in crop sciences is consistently increasing. Several advantageous effects of nanoparticles have been observed on crop plants. Copper (Cu) is an essential nutrient for the growth of plants and plays an important role in the photosynthetic reactions. Copper activates several enzymes, contributes in RNA synthesis and improve the performance of photosystems. But at higher level of Cu, seed germination and plant growth may be adversely affected. In the present study we administered copper oxide nanoparticle in varying concentration to assess the changes in germination percentage, root and shoot length, vigor index and total chlorophyll in soybean. Results showed a significant change in all the above parameters at 200ppm concentration in response to control. Thereafter high concentration of copper oxide nanoparticle proved to be toxic resulting in decrease in plant germination and decrease in vigor index and total chlorophyll.

Nanosilicon Particle Effects on Physiology and Growth of Woody Plants

Nanoparticles can influence key physiological processes including seed germination, photosynthesis, and thereby plant growth and yield. Despite several studies have addressed the effects of nanoparticles on crops, data for woody plant species is still scarce. In this report, the effects of silicon dioxide nanoparticles (SiO2 NPs) application, as potentially toxic elements, on physiological performance of 1-year-old woody plants, namely, hawthorn (Crataegus aronia L.) and mahaleb (Prunus mahaleb L.), were evaluated. Plants were irrigated with different concentrations of SiO2 NPs (0, 10, 50, and 100 mg L−1) for 45 days, and gas exchange parameters, relative water content (RWC), xylem water potential, growth, biomass allocation, and nutrient balance were recorded. Si concentration in leaves and its presence over the root surface were analyzed by XRF and SEM, respectively. Results showed diminishing RWC and xylem water potential with the increasing concentrations of SiO2 NPs, thereby confirming detrimental effects of SiO2 NPs irrigation on water status of the plants. Despite the poorer water status, photosynthesis rate (A), stomatal conductance (gs), and transpiration rate (E) were not affected by SiO2 NPs treatments but improved marginally in both species. Overall, the application of SiO2 NPs slightly enhanced plant growth in both species, more evidently in hawthorn, particularly because roots were benefited in growth and length. The presence of SiO2 NPs on the root surfaces was pragmatic in both the species using SEM. XRF analysis of the leaf tissue confirmed that Si concentration in leaf tissues increased at increasing levels of SiO2 NPs, whereas concentrations of examined macronutrients, i.e., nitrogen, phosphorus, and potassium, remain unaffected at increasing levels of SiO2 NPs application. In conclusion, although water status of the woody plants was slightly disrupted by SiO2 NPs, such negative effects were not reflected on plant physiological performance. Therefore, the results should be carefully interpreted as current research reveals that SiO2 NPs application to a certain extent can (contrary to expected) aid slight improvement in leaf physiological performance as well as in root elongation, finally contributing to enhanced plant growth. However, toxic effects, as exhibited by exposure of longer duration and/or higher concentrations of SiO2 NPs, cannot be ruled out in plants, a topic that unavoidably merits further experimental investigation in woody species.

Effect of Different modes and Concentrations of ZnO Nano particles on Floral properties of Sunflower variety SSH6163

Nanotechnology has the potential to reinforce the missiontoward ever-green revolution by enhancing agricultural productivity with limited inputs. Zinc plays a vital role in growth hormone production, internode elongation and sexual reproduction by affecting production and shape of pollen and changes in the stigma. Keeping above facts under consideration an experiment was conducted to study the effect of Zincoxide nanoparticles(ZnONPs) on reproductive and biochemical parameters in sunflower. ZnONPs treated and untreated seeds of sunflower were grown in sand culture supplemented with zinc deficient Hoaglandsolution in order to provide representative indication of the impact of ZnONPs on plants under environmentally relevant conditions. Plants treated with ZnONPs exhibited early flowering, improved pollen viability and high starch content in pollens with respect tocontrol. Flowers bloomed first in seeds and plants treated with ZnONPs at a concentration of 250 ppm, followed by 1000 ppm oftreated seeds and untreated sand. The highest pollen viability was observed in treated seeds and treated plant at a concentrationof 500 ppm and the lowest in treated seeds with foliar application at 1000 ppm. Starch content was the highest at 250 ppm in treated seeds and untreated plants and the lowest in treated seeds and treated plants at 500 ppm concentration. This experiment revealed that ZnONPs has exhibited note worthy effect onreproductive and biochemical parameters of sunflower plant at different concentrations and under different modes of application.

Physiological performance of two contrasting rice varieties under water stress.

Two rice varieties PR-115 and Super-7 were imposed to water stress and different physiological traits were monitored to evaluate the performance of these varieties under drought. Under water stress condition although the relative water content, osmotic potential, chlorophyll content, photosynthesis rate, carbon discrimination and biomass decreased in both the varieties however, the reduction was more pronounced in Super-7 variety. Oryzanol a trans-ester of ferulic acid functions as antioxidant and it increased along with total phenolic and anthocyanin content in both the varieties under drought stress. However, gallic acid, 4 hydroxy benzoic acid, syringic acid and chlorogenic acid showed differential pattern in both of the varieties under water limiting conditions. Under drought, grain yield was penalized by 17 and 54% in PR-115 and Super-7 varieties, respectively in comparison to watered plants. Super-7 variety showed pronounced electrolyte leakage and MDA enhancement under water stress condition. High non photochemical quenching and reduction in Y(NO) and Y(II) indicated balanced energy management in tolerant PR-115 variety. The studies showed that PR-115 is a drought tolerant variety while Super-7 is drought sensitive in nature.

Effect of Drought Stress on Biochemical Changes in Drought Tolerant and Drought Sensitive Barley (Hordium vulgare L.) Cultivars

Drought is a major stress that dramatically limits plant growth and productivity. Polyethylene glycol (PEG) has been used for osmotically induced water stress studies in plants. The present work was designed to examine the biochemical response in six barley varieties (three tolerant and three sensitive) at different osmotic potential of Polyethylene glycol-6000 (PEG-6000). The results showed at-3.0 bars osmotic potential of PEG-6000 decreased total chlorophyll and an increase in electrolyte leakage and catalase activity was observed in barley leaves.