Praveen K. Saxena

University of Guelph | UOGuelph

Hyptis suaveolens (L.) Poit is known for containing podophyllotoxin (PTOX), a natural lignan used as the lead compound in antitumor agent preparations, in its roots. The use of phloroglucinol (PHL) and indoleamines, such as melatonin (MEL) and serotonin (SER), in plant tissue culture is a promising alternative for eliciting rare and high-value seco...

Plant growth regulators (PGRs) play a vital role in the induction of morphogenesis in vitro. Synthetic PGRs are commonly used to induce organogenesis and somatic embryogenesis from various explants, while natural substances are rarely utilized. This study aimed to enhance the regenerative response in Nicotiana tabacum leaf explants using Tulsi (Oci...

The medicinal plant tulsi (Ocimum sanctum L.) is acknowledged for its invigorating and healing properties that enhance resilience to stress in various human and animal models by modulating antioxidant compounds. While extensive research has documented these effects in humans, the adaptogenic potential of tulsi in stressful in vitro plant systems ha...

Stability of metabolites in harsh environments such as drought, temperature, and light suggest their untapped potential in processes the plants utilize in mitigation of abiotic and biotic stresses. Such metabolites could be nonspecific to microorganisms, plants, or animals. Many of the indoleamines are ubiquitous throughout species and have been sh...

Black knot (BK) is a deadly disease of European (Prunus domestica) and Japanese (Prunus salicina) plums caused by the hemibiotrophic fungus Apiosporina morbosa. Generally, phytopathogens hamper the balance of primary defense phytohormones, such as salicylic acid (SA)–jasmonic acid (JA) balance, for disease progression. Thus, we quantified the impor...

Black Knot (BK) is a deadly disease of European (Prunus domestica) and Japanese (Prunus salicina) plums caused by the hemibiotrophic fungus Apiosporina morbosa. Generally, phytopathogens hamper the balance of primary defense phytohormones such as salicylic acid (SA)-jasmonic acid (JA) balance for disease progression. Thus, we quantified the importa...

Citation: Shinde, R.; Ayyanath, M.-M.; Shukla, M.; El Kayal, W.; Saxena, P.; Subramanian, J. Hormonal Interplay Leading to Black Knot Disease Establishment and Progression in Plums. Plants 2023, 12, 3638. https://doi. Abstract: Black Knot (BK) is a deadly disease of European (Prunus domestics) and Japanese (Prunus salicina) plums caused by the hemi...

Black Knot (BK) is a deadly disease of European (Prunus domestics) and Japanese (Prunus salicina) plums caused by the hemibiotrophic fungus Apiosporina morbosa. After infection, the appearance of warty black knots indicates a phytohormonal imbalance in infected tissues. Based on this hypothesis, we quantified phytohormones such as indole-3-acetic a...

Climate change is forcing physiological changes, especially in temperate trees, in which the reproduction phase has been affected harshly, eventually resulting in poor performance. Erratic fluctuations during the flowering periods, predominantly in cold-sensitive, yet industry-desired (sourced), hazelnut cultivars have been causing at least a 10-fo...

Hazelnuts have recently gathered tremendous attention due to the expansion of the confectionary industry. However, the sourced cultivars fail to perform in initial phase of cultivation as they enter bare survival mode due to changes in climatic zones, for example, Southern Ontario, where the climate is continental, as opposed to the milder climate...

The Ascomycete Ophiostoma novo-ulmi threatens elm populations worldwide. The molecular mechanisms underlying its pathogenicity and virulence are still largely uncharacterized. As part of a collaborative study of the O. novo-ulmi-elm interactome, we analyzed the O. novo-ulmi ssp. americana transcriptomes obtained by deep sequencing of messenger RNAs...

Plant diversity is critical to the functioning of human societies, and evidence shows that plant conservation success is driven by integrative approaches that include social and biological factors. Plants have a unique capacity to reproduce asexually, and propagation practices can yield large numbers of plantlets. These plantlets can be used in sev...

American chestnut (Castanea dentata), a native species of eastern North America, is an economically important deciduous hardwood tree that has been designated as endangered in Canada. The population of American chestnut trees has dwindled significantly across Southern Ontario due to chestnut blight and many of the surviving trees continue to show b...

Dutch elm disease (DED), caused by Ophiostoma novo-ulmi (Onu), is a destructive disease of American elm (Ulmus americana L.). The molecular mechanisms of resistance and susceptibility against DED in American elm are still largely uncharacterized. In the present study, we performed a de novo transcriptome (RNA-sequencing; RNA-Seq) assembly of U. ame...

Cryopreservation is an effective tool for long-term preservation of plant species. The cryopreservation protocols are often plant specific and must be optimized for each species in order to maximize regeneration following the storage at ultra-low temperature of -196�C. Recently, the droplet vitrification method has been widely adopted for cryoprese...

Honeycrisp' (Malus domestica Borkh.), a premium applecultivar, is highly susceptible to bitter pit and decline in quality during long-term storage. In order to enhance the quality, an aque-ous composition containing hexanal was applied as a preharvest spray. The effects of hexanal were assessed on the treated fruit and compared with Harvista TM (a...

Yukon Draba (Draba yukonensis) is a small, short-lived perennial mustard species that is endemic to southwestern Yukon in Canada. This plant has been categorized as a species of Special Concern. It faces the threat of habitat loss due to natural and man-made causes and a population that is unevenly distributed to a few large and several small subpo...

Coffee (Coffea spp.) is an important tropical agricultural crop that has significant economic and social importance in the world. The ex situ conservation of plant genetic resources through seeds is not feasible due to the sensitivity of coffee seed to desiccation and low temperatures. The cryopreservation of zygotic embryos may allow for an effici...

Cryopreservation is considered an ideal strategy for the long-term preservation of plant genetic resources. Significant progress was achieved over the past several decades, resulting in the successful cryopreservation of the genetic resources of diverse plant species. Cryopreservation procedures often employ in vitro culture techniques and require...

Apples (Malus domestica Borkh) are prone to preharvest fruit drop, which is more pronounced in ‘Honeycrisp’. Hexanal is known to improve fruit retention in several economically important crops. The effects of hexanal on the fruit retention of ‘Honeycrisp’ apples were assessed using physiological, biochemical, and transcriptomic approaches. Fruit re...

In grafted plants, the movement of long-distance signals from rootstocks can modulate the development and function of the scion. To understand the mechanisms by which tolerant rootstocks improve scion responses to osmotic stress (OS) conditions, mRNA transport of osmotic responsive genes (ORGs) was evaluated in a tomato/potato heterograft system. I...

The growth and productivity of several apple rootstocks have been evaluated in various previous studies. However, limited information is available on their tolerance to osmotic stress. In the present study, the physiological and molecular responses as well as abscisic acid (ABA) levels were assessed in six apple rootstocks (M26, V3, G41, G935, B9 a...

Apples ( Malus domestica Borkh) are prone to pre-harvest fruit drop which is more pronounced in ‘Honeycrisp’. Using a transcriptomic approach, we analyzed the molecular mechanisms of fruit retention in ‘Honeycrisp’. A total of 726 differentially expressed genes (DEGs) were identified in the abscission zone of hexanal-treated and untreated fruit (FA...

Cryopreservation is a valuable tool that could potentially create an alternate plant preservation strategy for species at risk such as Hill’s thistle. The present study is focused on a successful paradigm involving conservation, propagation and redistribution (CPR), emaphasizing the usefulness of cryopreservation techniques for plant conservation u...

Hazelnut (Corylus spp.) flowering occurs during late winters and early spring which coincides with erratic fluctuating weather patterns. Irregular and reduced precipitation, especially in the form of snow, is assumed to dictate poor flowering and enhanced injury to catkins, especially in the sourced cultivars of interest to growers. We investigated...

Tulsi (Ocimum sanctum L.) is a sacred plant of medicinal and spiritual significance in many cultures. Medicinal properties of Tulsi are ascribed to its phytochemicals with antioxidant capabilities. The current study was undertaken to screen a large seed population of Tulsi to select germplasm lines with high antioxidant potential and to standardize...

Cryopreservation in liquid nitrogen (− 196 °C) ensures safe and cost-effective conservation of plant genetic resources using diverse materials, including roots. To date, successful cryopreservation of root explants isolated from in vitro grown plants as well as adventitious and hairy root cultures has been reported in large numbers of plant species...

Salinity is a major environmental stress in agriculture with significantly detrimental effects on crop productivity. The development of strategies to enhance salinity stress tolerance in plants is essential to ensure crop production in saline environments. Melatonin (Mel) and serotonin (Ser) accumulate in response to environmental stresses and are...

Conservation of threatened flora in genetic collections ex situ using in vitro culture and cryopreservation is receiving an increasing recognition as a complementary strategy to in situ conservation in natural habitats. The present study is focused on an integrated approach which involves conservation and propagation, emphasizing the usefulness of...

Thidiazuron (TDZ) is a diphenylurea synthetic herbicide and plant growth regulator used to defoliate cotton crops and to induce regeneration of recalcitrant species in plant tissue culture. In vitro cultures of African violet thin petiole sections are an ideal model system for studies of TDZ-induced morphogenesis. TDZ induces de novo shoot organoge...

IntroductionPlants respond to changes in their environments through hormonal activation of a physiological cascade that redirects metabolic resources and growth. In filberts (Corylus sp.), chelated iron promotes the growth of new shoots but the mechanism(s) are not understood.Objectives To use untargeted metabolomics and hormonomics approaches to g...

Hill’s thistle (Cirsium hillii (Canby) Fernald) is a perennial plant endemic to the Great Lakes region of North America. Hill’s thistle is listed as threatened in Ontario and Canada where it is found in globally rare alvar habitats. The main objective of this study was ex-situ conservation of Hill’s thistle using in vitro culture techniques and rei...

Commercial micropropagation of hybrid hazelnuts (Corylus avellana L. × C. americana Marshall) has been limited, owing to their poor rooting ability in vitro as well as ex vitro, leading to high mortality of plantlets transplanted in the greenhouse. The objective of this study was to develop an efficient and cost-effective protocol for rooting and p...

Plant tissue culture techniques have been used to propagate horticultural crops at a commercial scale for more than three decades. However, due to the high cost it is generally only used for high value crops. To increase production efficiency and make micropropagation viable for a wider range of species, new approaches to address key steps of the p...

The twentieth century witnessed deterioration of biodiversity and loss of natural habitats of many plant species. However, it was also an era of significant progress in tissue culture technology which opened further vistas for multiplication and conservation of plant species. Synthetic seed technology is one such method which involves selection of...

In spite of their lack of central organized nervous system, plants possess many of the same signaling compounds which are employed in the mammalian nervous system and commonly referred to as neurotransmitters or neuromodulators. These include classes such as the indoleamines, melatonin and serotonin, and the catecholamines, dopamine, epinephrine (a...

In the 60 years since Skoog and Miller first reported the chemical redirection of plant growth the underlying biochemical mechanisms are still poorly understood, with one challenge being the capacity for applied growth regulators to act indirectly or be metabolized to active phytohormones. We hypothesized that tryptophan is metabolized to auxin, me...

The full version can be viewed at https://rdcu.be/bKVOL In this study, an effective root-based cryopreservation method was developed for Hypericum perforatum L., an important medicinal species, using in vitro plants. A systematic approach was applied to determine effective combinations of protocol steps such as preculture, osmoprotection, vitrifica...

Main conclusion This DNA fingerprinting test confirmed 195 unique Corylus sp. accessions that were used to build a reference database for identity verification of unknown hazelnut trees from three locations in Ontario. Abstract Hazelnut is one of the most profitable tree nuts worldwide. Development of a hazelnut industry in Ontario is urgently req...

Hazelnuts (Corylus avellana) are monoecious, wind-pollinated, and self-incompatible, which guarantees cross-pollination and genetic diversity. Also, they are dichogamous, and in many locations male flowers open earlier than female flowers. Pollination starts with catkin elongation, differentiation of anthers, and release of pollen, which spreads wi...

Melatonin and serotonin are important phytochemicals enabling plants to redirect growth in response to environmental stresses. Despite much research on their biosynthetic routes, localization of their biosynthetic enzymes and recent identification of a phytomelatonin receptor, localization of the molecules themselves has to date not been possible....

The objective of the current study was to provide a preliminary assessment on the conservation status of Canadian medicinal plants in order to help guide future efforts to protect biocultural diversity in Canada. Using data provided from the Native American Ethnobotany Database (http://naeb.brit.org/), United States Department of Agriculture (https...

An efficient method for in vitro propagation of the bryophyte moss Plagiomnium cuspidatum (Hedw.) T.J. Kop is presented. Protocol optimization investigated media salt strength (quarter, third, or half-strength Murashige and Skoog; MS), sugar concentration (1 to 3% (w/v) sucrose), growth regulator content (presence of benzylaminopurine (BA) at 0–5 μ...

Thidiazuron (TDZ) is a substituted phenylurea first synthesized in 1967 by the Schering Corporation in Germany. Compared to other plant growth regulators, TDZ is a powerful and potent synthetic growth regulator, leading to a wide array of in vitro and in vivo applications in plants including prevention of leaf yellowing, enhanced photosynthetic act...

In this study conservation of Castilleja levisecta Greenm., a globally endangered species was addressed through in vitro cryopreservation of shoot tips. In vitro cultures were successfully established using seedlings received from British Columbia, Canada. Shoot tips excised from in vitro propagated plants were cryopreserved using a droplet-vitrifi...

Golden paintbrush (Castilleja levisecta Greenm.) is a hemiparasitic herbaceous perennial native to the Pacific Northwest of North America and is considered critically imperilled with only 11 populations remaining in the wild. The main objective of this study was to develop ex situ and in situ conservation through micropropagation and field planting...

Melatonin is a ubiquitously present indoleamine with a vast capacity for modulating the growth and behavior of plants, animals, and microbes. Though melatonin was discovered in plants decades after its discovery in mammals, its presence has now been confirmed in almost all plant families. Despite this, the in vitro and in vivo mechanisms of action...

This report presents a simple, rapid and accessible validated method for quantification of eight major plant growth regulators (PGR): cytokinins (6-(γ,γ-dimethylallylamino)purine (2-iP), benzylaminopurine (BA) and zeatin), auxin (indole-3-acetic acid; IAA), jasmonic acid (JA), salicylic acid (SA), gibberellic acid (GA3) and abscisic acid (ABA) by l...

Melatonin and serotonin are important signaling and stress mitigating molecules that play important roles across growth and development in plants. Despite many well-documented responses, a systematic investigation of the entire metabolic pathway (tryptophan, tryptamine and N-acetylserotonin) does not exist, leaving many open questions. The objectiv...

Tolerance to Dutch elm disease (DED) has been linked to the rapid and/or high induction of disease-responsive genes after infection with the fungus Ophiostoma novo-ulmi. Although the fungal infection by O. novo-ulmi primarily takes places in xylem vessels, it is still unclear how xylem contributes to the defense against DED. Taking advantage of the...

Serotonin is a neurotransmitter than has been identified across all forms of life. In recent years the presence and function of serotonin in plants (phytoserotonin) is becoming an increasingly active area of research. Serotonin has been found to function as a plant growth regulator, and a stress defense molecule. Through these functions serotonin h...

Attempts of clonal propagation of sugar maple through conventional and micropropagation techniques have been largely unsuccessful and the basis for this longstanding problem has remained unknown. Typical symptoms of stress in in vitro cultures of sugar maple and its intrinsic tolerance to highly shaded growing conditions indicated that optimization...

American Elms were devastated by an outbreak of Dutch Elm Disease is caused by the fungus Ophiostoma novo-ulmi Brasier that originated in Asia and arrived in the early 1900s. In spite of decades of study, the specific mechanisms and disease resistance in some trees is not well understood. the fungus is spread by a number of species of bark beetles...

A simple and efficient system was developed for the rapid in vitro multiplication of Baptisia australis using nodal explants derived from axenic cultures. Among the four cytokinins [benzylaminopurine (BA), kinetin, N6-(2-isopentenyl)adenine (2-iP) and zeatin] tested for axillary bud induction, BA at 4.4 µM proved to be the most effective treatment...

Melatonin is an indoleamine neurotransmitter that has recently become well established as an important multi-functional signalling molecule in plants. These signals have been found to induce several important physiological responses that may be interpreted as behaviours. The diverse processes in which melatonin has been implicated in plants have ex...

The genus Panax belongs to the taxonomic family Araliaceae and consists of many species that are commonly referred to as ginseng. The plants are perennial herbs that grow mostly in the wild and only a few are cultivated. Geographically, they are mainly distributed in North America and northeast Asia. The species contain bioactive chemicals includin...

Background: Due to the complex process of designing and manufacturing new plant tissue culture vessels through conventional means there have been limited efforts to innovate improved designs. Further, development and availability of low cost, energy efficient LEDs of various spectra has made it a promising light source for plant growth in controll...

Despite growing evidence of the importance of melatonin and serotonin in the plant life, there is still much debate over the stability of melatonin, with extraction and analysis methods varying greatly from lab to lab with respect to time, temperature, light levels, extraction solvents, and mechanical disruption. The variability in methodology has...

Bacterially-contaminated water is a major health concern leading to infectious diseases in emerging nations. The use of copper (Cu) and silver (Ag) wire independently, and Cu wire in combination with synthetic sunlight (SySu), were investigated as a low-cost water treatment method. Water inoculated with 1, 100 colony forming units/mL of Escherichia...

Study objectives: Melatonin is an important neurohormone, which mediates circadian rhythms and the sleep cycle. As such, it is a popular and readily available supplement for the treatment and prevention of sleep-related disorders including insomnia and jet lag. This study quantified melatonin in 30 commercial supplements, comprising different bran...

Serotonin is an ancient indoleamine that was presumably part of the life cycle of the first prokaryotic life forms on Earth millions of years ago where it functioned as a powerful antioxidant to combat the increasingly oxygen rich atmosphere. First identified as a neurotransmitter signaling molecule in mammals, it is ubiquitous across all forms of...