Mayank Anand Gururani

Eucalyptus globulus Labill. is one of the most widely utilized medicinal plants throughout the world due to its wide spectrum of interesting biological activities that are mainly attributed to the diversity of phytochemical constituents in the plant parts. The emerging crisis of pathogen resistance for conventional antibiotics is considered a global concern for the diminishing effectiveness of antibiotics; hence, there is an urgent need to explore new antimicrobial ingredients from botanical sources, among which the most promising sources are medicinal plants. Moreover, the growing limitation toward synthetic antioxidants motivated the scientific community all over the world to identify plant-acquired antioxidants and antimicrobials. This is a huge global challenge, because of the increasing public health awareness and reliance on natural compounds, as these compounds are safer alternatives. Moreover, the undesirable impacts of synthetic pharmaceuticals can be avoided. Furthermore, ...

In this study, the effects of melatonin-induced enhancement on the principal photosynthetic parameters and antioxidant machinery were investigated in Avena sativa (oat) plants exposed to polyethylene glycol (PEG)-induced osmotic stress. The parameters of growth, chlorophyll content, stomatal conductance, proline accumulation, lipid peroxidation, and electrolyte leakage showed noteworthy improvements between the groups. Melatonin treatment caused upregulation of the genes that encode the three major antioxidant enzymes: ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT). Chlorophyll-a fluorescence kinetic analyses revealed that melatonin treatment improved performance indices (PIABS and PItotal), quantum yields, and efficiencies of photosystem II (PSII) in oat plants subjected to PEG-induced osmotic stress. Furthermore, upregulation of five genes (PsbA, PsbB, PsbC, PsbD, and PsbO) that encode the core proteins of PSII implied melatonin exerted a positive influe...

Recent studies have demonstrated melatonin protects various crops against abiotic stresses. However, the effects of melatonin on the photosynthetic apparatus of stressed plants is poorly characterized. We investigated the effects of melatonin pretreatment on photosynthesis and tolerance to salinity stress in Avena sativa (oat) plants. Oat plants were exposed to four treatments (three replicate pots per treatment): well-watered (WW; control); watered with 300 mM salt solution for 10 days (NaCl); pretreated with 100 µM melatonin solution for 7 days then watered normally for 10 days (Mel+W); or pretreated with 100 µM melatonin for 7 days then 300 mM salt for 10 days (Mel+NaCl). Considerable differences in growth parameters, chlorophyll content, stomatal conductance, proline accumulation, lipid peroxidation, electrolyte leakage, and growth parameters were observed between groups. Genes encoding three major antioxidant enzymes were upregulated in the Mel+NaCl group compared to the other ...

Sound vibration (SV), a mechanical stimulus, can trigger various molecular and physiological changes in plants like gene expression, hormonal modulation, induced antioxidant activity and calcium spiking. It also alters the seed germination and growth of plants. In this study, we investigated the effects of SV on the resistance of Arabidopsis thaliana against Botrytis cinerea infection. The microarray analysis was performed on infected Arabidopsis plants pre-exposed to SV of 1000 Hertz with 100 decibels. Broadly, the transcriptomic analysis revealed up-regulation of several defense and SA-responsive and/or signaling genes. Quantitative real-time PCR (qRT-PCR) analysis of selected genes also validated the induction of SA-mediated response in the infected Arabidopsis plants pre-exposed to SV. Corroboratively, hormonal analysis identified the increased concentration of salicylic acid (SA) in the SV-treated plants after pathogen inoculation. In contrast, jasmonic acid (JA) level in the S...

Sound vibration (SV) is considered to be a mechanical stimulus which gives rise to various physiological and molecular changes in plants. Previously, we identified 17 SV-regulated genes (SRGs) which were up-regulated by SV treatments in Arabidopsis. Here, we analyzed the expression pattern of similar genes after an exposure of 500 Hertz at 80 decibels, for various time periods. Simultaneously, we confirmed the SV-mediated expression of these genes under lighted condition as many of them were reported to be dark-induced. For this, we designed an improved SV treatment chamber. Additionally, we checked the electrolyte leakage (EL), photosynthetic performance and expression of mechanosensitive (MS) ion channel genes after 5 days of SV treatment in the illuminated chamber. EL was higher, and the photosynthetic performance index was lower in the SV-treated plants compared to control. Seven out of the 13 MS ion channel genes were differentially expressed after the SV treatment. Simultaneously, we checked the touch-mediated expression pattern of 17 SRGs and 13 MS ion channel genes. The distinct expression pattern of 6 SRGs and 1 MS ion channel gene generate an idea that SV as a stimulus is different from touch. Developmental stage-specific expression profiling suggested that the majority of the SRGs were expressed spatiotemporally in different developmental stages of Arabidopsis, especially in imbibed seed, seedlings and leaves.

Bacillus subtilis CB-R05, possessing antagonistic effects against several fungal pathogens, is a diazotrophic plant growth-promoting bacteria marked with the green fluorescent protein (gfp) gene. To confirm the expression level of the pathogenesis-related (PR) proteins in rice inoculated with CB-R05, the expressions of four pathogenesis-related (PR) proteins (PR2, PR6, PR15, and PR16) were examined in the rice leaves treated with wounding stress over a time period. The PR proteins were generally more strongly expressed in the rice leaves inoculated with CB-R05 compared with the untreated control. The marked gfp-tagged B. subtilis CB-R05 strain was inoculated onto the rice seedlings under axenic conditions. Under the confocal laser scanning microscope (CLSM), the gfp-tagged CB-R05 bacterial cells were observed to penetrate the rhizoplane, especially in the elongation and differentiation zones of the rice roots, and colonize the root intracellularly. The bacteria, 24 h after the gfp-tagged CB-R05 inoculation, were seen to penetrate into the cell wall, cortex, xylem, and concentrate mainly in the vascular bundle. Numerous bacteria were observed within the intercellular spaces, root cortical cells, and xylem vessels. Over time, these bacteria dispersed to the lateral root junctions and propagated slowly from the roots to the stems and leaves. The B. subtilis CB-R05 population in the rice root rhizosphere was also monitored. These results show a very widespread colonization of the B. subtilis CB-R05 in the rice rhizosphere. Further attempts are under way to investigate the competition between the CB-R05 bacteria and the fungal pathogen in vivo.

Abiotic stress accounts for huge crop losses every year across the globe. In plants, the photosynthetic machinery gets severely damaged at various levels due to adverse environmental conditions. Moreover, the reactive oxygen species (ROS) generated as a result of stress further promote the photosynthetic damage by inhibiting the repair system of photosystem II. Earlier studies have suggested that phytohormones are not only required for plant growth and development, but they also play a pivotal role in regulating plants' responses to different abiotic stress conditions. Although, phytohormones have been studied in great detail in the past, their influence on the photosynthetic machinery under abiotic stress has not been studied. One of the major factors that limits researchers fromelucidating the precise roles of phytohormones is the highly complex nature of hormonal crosstalk in plants. Another factor that needs to be elucidated is the method used for assessing photosynthetic damage in plants that are subjected to abiotic stress. Here, we review the current understanding on the role of phytohormones in the photosynthetic machinery under various abiotic stress conditions and discuss the potential areas for further research.

Manganese-stabilizing protein (MSP) represents a key component of the oxygen-evolving complex (OEC). In the present study, transgenic potato lines with both enhanced (sense) and reduced (anti-sense) expression levels of MSP were generated to investigate the putative role of MSP in overall plant growth, particularly in tuber development. MSP antisense plants were found to exhibit higher tuber yield with increased total soluble carbohydrates. The photosynthetic efficiencies of the plants examined through the OJIP kinetics revealed that MSP-antisense plants were photosynthetically more active than the MSP-sense and control (UT) plants. The oxygen measurements indicated that the relative oxygen evolution was directly proportional to the MSP expression, as MSP-antisense plants showed much lower oxygen evolution compared to MSP-sense as well as UT plants. MSP-sense plants behaved like the UT plants with respect to morphology, tuber yield, and photosynthetic performance. Chlorophyll a fluo...

Chlorophyll-a fluorescence analysis provides relevant information about the physiology of plants growing under abiotic stress. In this study, we evaluated the influence of cold stress on the photosynthetic machinery of transgenic turfgrass, Zoysia japonica, expressing oat phytochrome A (PhyA) or a hyperactive mutant phytochrome A (S599A) with post-translational phosphorylation blocked. Biochemical analysis of zoysiagrass subjected to cold stress revealed reduced levels of hydrogen peroxide, increased proline accumulation, and enhanced specific activities of antioxidant enzymes compared to those of control plants. Detailed analyses of the chlorophyll-a fluorescence data through the so-called OJIP test exhibited a marked difference in the physiological status among transgenic and control plants. Overall, these findings suggest an enhanced level of cold tolerance in S599A zoysiagrass cultivars as reflected in the biochemical and physiological analyses. Further, we propose that chloroph...

Plants as sessile organisms are continuously exposed to abiotic stress conditions that impose numerous detrimental effects and cause tremendous loss of yield. Abiotic stresses, including high sunlight, confer serious damage on the photosynthetic machinery of plants. Photosystem II (PSII) is one of the most susceptible components of the photosynthetic machinery that bears the brunt of abiotic stress. In addition to the generation of reactive oxygen species (ROS) by abiotic stress, ROS can also result from the absorption of excessive sunlight by the light-harvesting complex. ROS can damage the photosynthetic apparatus, particularly PSII, resulting in photoinhibition due to an imbalance in the photosynthetic redox signaling pathways and the inhibition of PSII repair. Designing plants with improved abiotic stress tolerance will require a comprehensive understanding of ROS signaling and the regulatory functions of various components, including protein kinases, transcription factors, and phytohormones, in the responses of photosynthetic machinery to abiotic stress. Bioenergetics approaches, such as chlorophyll a transient kinetics analysis, have facilitated our understanding of plant vitality and the assessment of PSII efficiency under adverse environmental conditions. This review discusses the current understanding and indicates potential areas of further studies on the regulation of the photosynthetic machinery under abiotic stress.

Bacillus subtilis CB-R05, possessing antagonistic effects against several fungal pathogens, is a diazotrophic plant growth-promoting bacteria marked with the green fluorescent protein (gfp) gene. To confirm the expression level of the pathogenesis-related (PR) proteins in rice inoculated with CB-R05, the expressions of four pathogenesis-related (PR) proteins (PR2, PR6, PR15, and PR16) were examined in the rice leaves treated with wounding stress over a time period. The PR proteins were generally more strongly expressed in the rice leaves inoculated with CB-R05 compared with the untreated control. The marked gfp-tagged B. subtilis CB-R05 strain was inoculated onto the rice seedlings under axenic conditions. Under the confocal laser scanning microscope (CLSM), the gfp-tagged CB-R05 bacterial cells were observed to penetrate the rhizoplane, especially in the elongation and differentiation zones of the rice roots, and colonize the root intracellularly. The bacteria, 24 h after the gfp-t...

Here, we first report hyperparasitism of Honey Suckeled Mistletoe, Dendrophthoe falcata var. falcata (Loranthaceae) by Pseudaulacaspis cockerelli (Diaspididae). The infected mistletoe was found parasitising branches of the Senna siamea host. Pear-shaped white spots were observed on abaxial and adaxial leaf surfaces, stem and few on the haustorial surfaces of the mistletoe. Close inspection revealed a yellowish-brown spot on individual white spots. These were identified on the basis of morphological features as Cockerell ...

Phytochromes are photosensory phosphoproteins with crucial roles in plant developmental responses to light. Functional studies of individual phytochromes have revealed their distinct roles in the plant's life cycle. Given the importance of phytochromes in key plant developmental processes, genetically manipulating phytochrome expression offers a promising approach to crop improvement. Photo-biotechnology refers to the transgenic expression of phytochrome transgenes or variants of such transgenes. Several studies have indicated that crop cultivars can be improved by modulating the expression of phytochrome genes. The improved traits include enhanced yield, improved grass quality, shade-tolerance, and stress resistance. In this review, we discuss the transgenic expression of phytochrome A and its hyperactive mutant (Ser599Ala-PhyA) in selected crops, such as Zoysia japonica (Japanese lawn grass), Agrostis stolonifera (creeping bentgrass), Oryza sativa (rice), Solanum tuberosum (potato), and Ipomea batatas (sweet potato). The transgenic expression of PhyA and its mutant in various plant species imparts biotechnologically useful traits. Here, we highlight recent advances in the field of photo-biotechnology and review the results of studies in which phytochromes or variants of phytochromes were transgenically expressed in various plant species. We conclude that photo-biotechnology offers an excellent platform for developing crops with improved properties.

Piriformospora indica is an axenically cultivable phytopromotional endosymbiont that mimics capabilities of arbuscular mycorrhizal fungi. This is a basidiomycete of the Sebacinaceae family, which promotes growth, development, and seed production in a variety of plant species. We report that the cell wall extract (CWE) from P. indica induces tuberization in vitro and promotes tuber growth and yield in potato. The CWE altered the calcium signaling pathway that regulates tuberization process. An increase in tuber number and size was correlated with increased transcript expression of the two Ca2+-dependant proteins (CaM1 and St-CDPK1) and the lipoxygenase (LOX) mRNA, which are known to play distinct roles in potato tuberization. External supplementation of Ca2+ ions induced a similar set of tuberization pathway genes, indicating presence of an active Ca2+ in the CWE of P. indica. Since potato tuberization is directly influenced by the presence of microflora in nature, the present study provides an insight into the novel mechanism of potato tuberization in relation to plant–microbe association. Ours is the first report on an in vitro tuber-inducing beneficial fungus.

Potato tuberization is a complicated biochemical process, which is dependent on external environmental factors. Tuber development in potato consists of a series of biochemical and morphological processes at the stolon tip. Signal transduction proteins are involved in the source-sink transition during potato tuberization. In the present study, we examined protein profiles under in vitro tuber-inducing conditions using a shotgun proteomic approach involving denaturing gel electrophoresis and liquid chromatography–mass spectrometry. A total of 251 proteins were identified and classified into 9 groups according to distinctive expression patterns during the tuberization stage. Stolon stage-specific proteins were primarily involved in the photosynthetic machinery. Proteins specific to the initial tuber stage included patatin. Proteins specific to the developing tuber stage included 6-fructokinase, phytoalexin-deficient 4-1, metallothionein II-like protein, and malate dehydrogenase. Novel stage-specific proteins identified during in vitro tuberization were ferredoxin–NADP reductase, 34 kDa porin, aquaporin, calmodulin, ripening-regulated protein, and starch synthase. Superoxide dismutase, dehydroascorbate reductase, and catalase I were most abundantly expressed in the stolon; however, the enzyme activities of these proteins were most activated at the initial tuber. The present shotgun proteomic study provides insights into the proteins that show altered expression during in vitro potato tuberization.► A total of 251 proteins during tuberization in vitro were identified and classified into 9 distinctive expression patterns. ► Eight novel proteins were identified, containing aquaporin, calmodulin and DDTFR10 which expressed constantly throughout the tuberization in vitro. ► Photosynthesis-related proteins are most highly expressed at stolon. ► Proteins in carbon metabolism are mainly expressed at initial and developing tuber stage. ► ROS-metabolizing enzymes are expressed at specific tuber stage, showing a little difference of maximal expression compared to tuberization in vivo.

Glucosinolates (GSL) and their derivatives are well known for the characteristic roles they play in plant defense as signaling molecules and as bioactive compounds for human health. More than 130 GSLs have been reported so far, and most of them belong to the Brassicaceae family. Several enzymes and transcription factors involved in the GSL biosynthesis have been studied in the model plant, Arabidopsis, and in a few other Brassica crop species. Recent studies in GSL research have defined the regulation, distribution, and degradation of GSL biosynthetic pathways; however, the underlying mechanism behind transportation of GSLs in plants is still largely unknown. This review highlights the recent advances in the metabolic engineering of GSLs in plants and discusses their potential applications.

ABSTRACT. Selection marker genes (SMGs) have been commonly used in genetic transformation of plants for efficient selection of transformed cells, tissue, or regenerated shoots. In the majority of cases, the selection is based on antibiotic or herbicide resistance. The presence of such genes within the environment or in the food supply might pose an unpredictable hazard to the ecosystem and to human health; therefore research has been initiated to develop an efficient marker-free transgenic system.

Manganese stabilizing protein (MSP) is an important component of the Photosystem II (PSII) oxygen evolving complex. In our previous work, transgenic potato plants with reduced expression of MSP (MSP-As) were developed and their physiological and biochemical responses were studied. In this report, we address the response of MSP-As plants toward salinity, heavy metal and osmotic stresses.

Potato is one of the most important noncereal crops in the world today, and like other major crops, it is prone to substantial yield losses because of various factors including disease. Recent molecular advancements in plant–pathogen studies have led to the identification of various host genes involved in the plant’s defense against pathogen attack. These genes may encode antimicrobial peptides, enzymes for phytoalexin production, proteins involved in defense-signaling cascades, and hydrolytic enzymes or pathogenesis-related proteins that are directly or indirectly responsible for the plant’s defense responses following a pathogen attack. A plant’s disease-resistance (R) genes are another important group of genes that have been used with varying degrees of success in crop improvement programs. Cloning and characterization of these genes and the dissection of signal-transduction components of the defense response have greatly increased the scope for transgenic disease resistance. This article highlights the current scenario and potential of the molecular approaches to improve resistance against filamentous pathogens in potato.

In this report we address the changes in the
expression of the genes involved in ROS scavenging and
ethylene biosynthesis induced by the inoculation of plant
growth-promoting rhizobacteria (PGPR) isolated from
potato rhizosphere. The two Bacillus isolates used in this
investigation had earlier demonstrated a striking influence
on potato tuberization. These isolates showed enhanced
1-aminocyclopropane-1-carboxylic acid deaminase activity,
phosphate solubilization, and siderophore production.
Potato plants inoculated with these PGPR isolates were
subjected to salt, drought, and heavy-metal stresses. The
enhanced mRNA expression levels of the various ROSscavenging
enzymes and higher proline content in tubers
induced by PGPR-treated plants contributed to increased
plant tolerance to these abiotic stresses. Furthermore, the
photosynthetic performance indices of PGPR-inoculated
plants clearly exhibited a positive influence of these bacterial
strains on the PSII photochemistry of the plants.
Overall, these results suggest that the PGPR isolates used
in this study are able to confer abiotic stress tolerance in
potato plants.

Manganese-stabilizing protein (MSP) represents a key component of the oxygen-evolving complex (OEC). Transgenic potato plants with both enhanced (sense) and reduced (anti-sense) MSP expression levels were generated to investigate the possible physiological role of MSP in overall plant growth, particularly in tuber development. MSP antisense plants exhibited both higher tuberization frequency and higher tuber yield with increased total soluble carbohydrates. The photosynthetic efficiencies of the plants were examined using the OJIP kinetics; MSP-antisense plants were photosynthetically more active than the MSP-sense and UT (untransformed) control plants. The oxygen measurements indicated that the relative oxygen evolution was directly proportional to the MSP expression, as MSP-antisense plants showed much lower oxygen evolution compared to MSP-sense as well as UT plants. MSP-sense plants behaved like the UT plants with respect to morphology, tuber yield, and photosynthetic performance. Chlorophyll a fluorescence analyses indicate a possible lack of intact Oxygen Evolving Complexes (OECs) in MSP antisense plants, which allow access to internal non-water electron donors (e.g., ascorbate and proline) and consequently increase the Photosystem II (PSII) activity of those plants. These findings further indicate that this altered photosynthetic machinery may be associated with early tuberization and increased tuberization frequency.

Tomato (Solanum lycopersicum L.) is the second
most important vegetable crop in the world
after potato (Solanum tuberosum L.), and its
productivity is influenced by different abiotic
stresses. Though cultivated tomato is moderately
tolerant to various abiotic stresses, the
crop losses due to unfavorable environmental
conditions can be unpredictably severe. So
far, several efforts have been made to improve
abiotic stress tolerance in cultivated tomato
through cultural practices, breeding techniques,
and biotechnological approaches. Introgression
of abiotic stress tolerance to cultivated tomato
from more tolerant wild relatives through classical
breeding has been attempted with limited
success. However, genetic engineering based
on the introgression of genes that are known
to be involved in stress response and putative
stress tolerance could provide powerful tools
for improving abiotic stress tolerance in tomato
coupled with the growing knowledge of stress
physiology. The present review summarizes the
current status and future directions on the use
of biotechnological approaches to improve abiotic
stress tolerance in tomato.

Plant diseases can drastically abate the crop yields as the degree of disease outbreak is getting severe
around the world. Therefore, plant disease management has always been one of the main objectives of
any crop improvement program. Plant disease resistance (R) genes have the ability to detect a pathogen
attack and facilitate a counter attack against the pathogen. Numerous plant R-genes have been used with
varying degree of success in crop improvement programs in the past and many of them are being
continuously exploited. With the onset of recent genomic, bioinformatics and molecular biology techniques,
it is quite possible to tame the R-genes for efficiently controlling the plant diseases caused by
pathogens. This review summarizes the recent applications and future potential of R-genes in crop
disease management.