B.Sc. Ed. (Botany, Chemistry, Teacher Education) University of Mysore, India;
M.Sc. (Botany) University of Calicut, India;
Ph.D. (Biochemistry) Indian Institute of Science, Bangalore, India
Refereed publications in Journals- 80; Patents and Intellectual Properties-2; Disclosures-4; Chapters in Books- 27; Non-Refereed Contributions - 10; Research Reports -28; Conference Proceedings- 86; Edited Books- 9; Book reviews- 6; (h index-29, i10 index-57, citations-3686).
Most Significant Contributions to Research and/or to Practical applications:
My research is focused on the biochemistry of plant senescence, specifically pertaining to fruits and vegetables. Investigations on the role of phospholipase D (PLD) in membrane homeostasis and signal transduction have led to advances in the understanding of the mechanism of membrane deterioration that occur in nanodimensions during stress and senescence. The second aspect of my research is focused on understanding the mechanism of action of food components in disease prevention. The efficacy, bio-accessibility, bioavailability and the molecular mechanisms of action of nutraceuticals in fruits and processed products in relation to their cancer-preventive and anti-inflammatory actions are being investigated using mammalian cell lines, and in vivo models. The existence of nutraceutical components as nanocomplexes has opened a whole new approach to the research, unravelling mysteries on the biological properties of health-regulatory components.
Ethylene signal Transduction- Phospholipase D (PLD) and Membrane Deterioration:
Previous research has established the role of phospholipase D in membrane phospholipid degradation. PLD is stimulated both by elevated levels of calcium, as well as by a decrease in pH. Full length cDNAs for PLD α were isolated from tomato and strawberry fruits, and their sequences, as well as the primary structures of the predicted PLD proteins compared. The PLD α isoforms were predicted to be cytosolic proteins and possessed N-terminal C2 domains. C2 domains enable the recruiting of cytosolic proteins to the membrane in response to the elevation in cytosolic calcium, and potentially membrane PIP2 levels, during hormonal stimulation. A complete cDNA corresponding to PLDα C2 domain was cloned and expressed in E.coli, and the C2 protein was isolated and characterized. By contrast to mammalian and Arabidopsis C2 domains, tomato PLDα C2 possessed a much longer loop region, showed a much higher affinity to phosphatidic acid than phosphorylated phosphatidylinositols, and did not require calcium for membrane binding (Tiwari and Paliyath, 2011 a).
Practical Implications of Phospholipase D Inhibition:
Previous studies on the role of PLD in enhancing membrane deterioration suggested that inhibition of its activity has the potential to increase shelf life and quality of fruits, vegetables and flowers. Based on phospholipase D inhibiting properties of a naturally occurring plant component hexanal, technologies have been developed for enhancing the shelf life and quality of fruits, vegetables and flowers. Fruits such as apple, pear, cherry, peach, grape, banana, and tomato showed enhanced shelf life and quality in response to the application of hexanal compositions (Tiwari and Paliyath, 2011 b, Sharma et al., 2010; US patents #7198811, 6514914). Recent projects are targeted to achieve controlled release of hexanal in packaging systems using nanotechnology for increased efficiency, and the development of nanoemulsions for dip treatments of fruits and vegetables.
Fruit Polyphenols and Cancer Prevention:
Polyphenols such as flavonoids in apples have been identified as powerful inhibitors of calcium- and calmodulin-mediated biochemical processes. Abnormalities in signal transduction processes are associated with maladies such as cancer, and normalizing these activities using food components has the potential to achieve disease prevention. In general, fruit polyphenols are powerful scavengers of reactive oxygen species such as superoxide and hydroxyl radicals. These free radicals can cause gene mutations, an initiator of cancer, and inflammation processes that lead to cardiovascular and degenerative diseases. Grape polyphenols inhibited the growth and proliferation of cancer cells without affecting the growth and proliferation of normal cells (Hakimuddin et al., 2006, 2008). The polyphenols appear to cause an increase in cytosolic calcium in cancer cells, subsequently followed by a disruption of mitochondrial membrane potential, as well as membrane vesiculation and damage, eventually leading to apoptosis/necrosis of the cancer cell. Grape polyphenols effectively inhibited the growth of MDA-MB231 cancer cells transplanted into athymic nude mice in association with down-regulation of genes involved in the inflammatory pathway and cell cycle regulation. Recent studies show enhanced uptake of polyphenol nanocomplexes in cancer cells that may enable targeted delivery of health regulatory components and drugs specifically into cancer cells. As well, developing designer functional fruit products enriched in active components with increased bioavailability can potentially enhance their efficacy in disease prevention (cancer, inflammation) (Hakimuddin et al., 2006, 2008; Jacob and Paliyath, 2008, 2011).
Jincy, M., M. Djanaguiraman, P. Jeyakumar, K.S. Subramanian, S. Jayasankar, G. Paliyath. (2017). Inhibition of phospholipase D enzyme activity through hexanal leads to delayed mango (Mangifera indica L.) fruit ripening through changes in oxidants and antioxidant enzymes activity. Scientia Horticulturae. 218: 316-325.
Anusuya, P., R. Nagaraj, G.J. Janavi, K.S. Subramanian, G. Paliyath and S. Jayasankar. (2016). Pre-harvest sprays of hexanal formulation for extending retention and shelf-life of mango fruits. Scientia Horticulturae. 211: 231-240.
Dineshkumar, S., S. Sherif, S. Mohd Pak-Dek, G. Paliyath, I. El Sharkawy and J. Subramanian. (2016). Identification and characterization of genes involved in the fruit colour development of European plum. Journal of the American Society of Horticultural Science. 141 (5): 467-474.
Anusha, B., K. Sathya, S. Parthasarathy, K. Prabhakar, D. Raghu, G. Thiribhuvanamala, R. Ramjegathesh, K.S. Subramanian, G. Paliyath and S. Jayasankar. (2016). Effect of hexanal on mycelial growth and spore germination of Colletotrichum gloeosporioides and Lasiodiploidia theobromae of mango. Tropical Agriculture. 93: 312-316.
Gill, K.S., H.S. Dhalliwall, B.V.C. Mahajan, G. Paliyath and R.S. Boora. (2016). Enhancing postharvest shelf life and quality of guava (Psidium guajava L.) cv. Allahabad Safeda by pre-harvest application of hexanal containing aqueous formulation. Postharvest Biology and Technology. 112: 224-232.
Fatima, T., V. Kesari, I. Watt, D. Wishart, J.F. Todd, W.R. Schroeder, G. Paliyath and P. Krishna. (2015). Metabolite profiling and expression analysis of flavonoid, vitamin C, and tocopherol biosynthesis genes in the antioxidant rich sea buckthorn (Hippophae rhamnoides L.). Phytochemistry. 118: 181-191.
Correa-Betanzo, J., P. Padmanabhan, M. Corredig, J. Subramanian and G. Paliyath. (2015). Complex formation of blueberry (Vaccinium angustifolium) polyphenols during freeze drying and its influence on their biological activity. Journal of Agricultural and Food Chemistry. 63: 2935-2946.
Sherif, S., I. El-Sharkawy, J. Mathur, P. Ravindran, P. Kumar, G. Paliyath and J. Subramanian. (2015). A stable JAZ protein from peach mediates the transition from outcrossing to self-pollination. BMC Biology. 13: 11. DOI: 10.1186/s12915-015-01246.
Misran, A, P. Padmanabhan, J.A. Sullivan, S. Khanizdeh and G. Paliyath. (2015). Composition of phenolics and volatiles in strawberry cultivars and influence of preharvest hexanal treatment on their profiles. Canadian Journal of Plant Science. 95: 115-126.
Cheema, A., P. Padmanabhan, J. Subramanian, A. Blom and G. Paliyath. (2014). Improving quality of tomato (Solanum lycopersicum L.) by pre- and postharvest applications of hexanal-containing formulations. Postharvest Biology and Technology. 95: 13-19.
Correa-Betanzo, J., E. Allen-Vercoe, J. McDonald, K. Schroeter, M. Corredig and G. Paliyath. (2014). Stability and biological activity of wild blueberry (Vaccinium angustifolium) polyphenols during Simulated in vitro gastrointestinal digestion. Food Chemistry. 165: 522–531.
Sherif, S., I. El-Sharkawy, G. Paliyath and S. Jayasankar. (2013). PpERF3b, a transcriptional repressor from peach contributes to disease susceptibility and side branching in EAR-dependent and –independent fashion. Plant Cell Reports. Special issue in hormonal signalling. 32: 1111-1124.
Sherif, S., G. Paliyath and S. Jayasankar. (2012). Molecular characterization of peach PR genes and their induction kinetics in response to bacterial infection and signalling molecules. Plant Cell Reports. 31: 697-711.
Sherif, S., I. El Sharkawy, G. Paliyath and S. Jayasankar. (2012). Differential expression of peach ERF transcriptional activators in response to signaling molecules and inoculation with Xanthomonas campestris pv. Pruni. Journal of Plant Physiology. 169: 731-739.
Jacob, J.K. and G. Paliyath. (2012). Infusion of fruits with nutraceutical and health regulatory components for enhanced functionality. Food Research International. 45: 93-102.
Uchendu, E.E., G. Paliyath, D.C.W. Brown and P. Saxena (2011). In vitro propagation of North American Ginseng (Panax quinquifolius L). In Vitro Cellular & Developmental Biology - Plant. 47: 710-718.
Tiwari, K and G. Paliyath (2011). Microarray analysis of ripening-regulated gene expression and its modulation by 1-MCP and hexanal. Plant Physiology Biochemistry. 49: 329-340.
Tiwari, K and G. Paliyath (2011). Cloning, expression and functional characterization of the C2 domain from tomato phospholipase Dα. Plant Physiology Biochemistry. 49. 18-32.
Correa-Betanzo, J., J.K. Jacob, C. Perez-Perez and G. Paliyath (2011). Effect of a sodium caseinate edible coating on berry cactus (Myrtillocactus geometrizans) fruit phytochemicals. Food Research International. 44: 1897-1904.
Sharma, M., J.K. Jacob, J. Subramanian and G. Paliyath. (2010). Hexanal and 1-MCP treatments for enhancing the shelf life and quality of sweet cherry (Prunus avium L.). Scientia Horticulturae. 125: 239-247.
Oke, M., J.K. Jacob and G. Paliyath. (2010). Effect of soy lecithin in enhancing fruit juice/sauce quality. Food Research International. 43: 232-240.