BITS Faculty Publications

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    Role of phytohormones in regulating agronomically important seed traits in crop plants
    (Elsevier, 2023) Sharma, Rita
    Seed development is a complex process that commences after double fertilization. Both forward and reverse genetic studies have revealed the critical roles of phytohormones in regulating seed development and the associated agronomic traits. The growing evidence points to the complex interactions among underlying genetic pathways due to hormone cross talk or shared signaling components. Moving forward to deconvolute these complex interactions requires an in-depth understanding of the genes regulating individual hormone pathways. Here, we summarize the multifaceted roles of key genes regulating biosynthesis and signaling of plant hormones, and the broad spectrum of mechanisms underpinning hormone action during seed development. The gain- and loss-of-function phenotypes associated with agronomically important seed traits, namely, seed size, weight, shape, number, longevity, and dormancy, provide compelling evidence for the plant hormones as crucial metabolic engineering targets to optimize seed traits in crop plants.
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    Functional delineation of rice MADS29 reveals its role in embryo and endosperm development by affecting hormone homeostasis
    (OUP, 2013) Sharma, Rita
    Rice MADS29 has recently been reported to cause programmed cell death of maternal tissues, the nucellus, and the nucellar projection during early stages of seed development. However, analyses involving OsMADS29 protein expression domains and characterization of OsMADS29 gain-of-function and knockdown phenotypes revealed novel aspects of its function in maintaining hormone homeostasis, which may have a role in the development of embryo and plastid differentiation and starch filling in endosperm cells. The MADS29 transcripts accumulated to high levels soon after fertilization; however, protein accumulation was found to be delayed by at least 4 days. Immunolocalization studies revealed that the protein accumulated initially in the dorsal-vascular trace and the outer layers of endosperm, and subsequently in the embryo and aleurone and subaleurone layers of the endosperm. Ectopic expression of MADS29 resulted in a severely dwarfed phenotype, exhibiting elevated levels of cytokinin, thereby suggesting that cytokinin biosynthesis pathway could be one of the major targets of OsMADS29. Overexpression of OsMADS29 in heterologous BY2 cells was found to mimic the effects of exogenous application of cytokinins that causes differentiation of proplastids to starch-containing amyloplasts and activation of genes involved in the starch biosynthesis pathway. Suppression of MADS29 expression by RNAi severely affected seed set. The surviving seeds were smaller in size, with developmental abnormalities in the embryo and reduced size of endosperm cells, which also contained loosely packed starch granules. Microarray analysis of overexpression and knockdown lines exhibited altered expression of genes involved in plastid biogenesis, starch biosynthesis, cytokinin signalling and biosynthesis.
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    Microscale thermophoresis as a powerful tool for screening glycosyltransferases involved in cell wall biosynthesis
    (Springer Nature, 2020) Sharma, Rita
    Identification and characterization of key enzymes associated with cell wall biosynthesis and modification is fundamental to gain insights into cell wall dynamics. However, it is a challenge that activity assays of glycosyltransferases are very low throughput and acceptor substrates are generally not available
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    Development of gold nanoparticle-fungal hybrid based heterogeneous interface for catalytic applications
    (Elsiever, 2015-08) Panwar, Jitendra; Gangopadhyay, Subhashis
    Unsupported and free gold nanoparticles (Au NPs) represent great potential in the field of catalysis. However, shortcomings like agglomeration and loss of the precious catalyst has encouraged the development of supported Au NPs as catalyst with increased activity, selectivity, ease of separation from the reaction mixture and recyclability. The present work demonstrates an eco-friendly, rapid and facile synthesis of catalytically active bio-supported Au NPs using a soil fungus, Aspergillus japonicus AJP01. The dual role of the fungal isolate in synthesis as well as immobilization of Au NPs is the remarkable feature of the study. The fungus successfully reduced Au(III) into Au NPs containing principally Au(0) with a small percentage of Au(I) as revealed by X-ray photoelectron spectroscopy. The particles were spherical in shape and well distributed on fungal mycelia with size ranging predominantly between 15 and 20 nm. The as-synthesized nanoparticle-fungal hybrid was found to be highly efficient in catalyzing sodium borohydride mediated reduction reactions of 4-nitrophenol and hexacyanoferrate(III). The versatility of the bionanocatalyst was further demonstrated by catalyzing the A3 coupling reactions for the synthesis of propargylamines.
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    Utilizing metal tolerance potential of soil fungus for efficient synthesis of gold nanoparticles with superior catalytic activity for degradation of rhodamine B
    (Elsiever, 2016-08) Panwar, Jitendra
    In recent years, the surging demand of nanomaterials has boosted unprecedented expansion of research for the development of high yielding and sustainable synthesis methods which can deliver nanomaterials with desired characteristics. Unlike the well-established physico-chemical methods which have various limitations, biological methods inspired by mimicking natural biomineralization processes have great potential for nanoparticle synthesis. An eco-friendly and sustainable biological method that deliver particles with well-defined shape, size and compositions can be developed by selecting a proficient organism followed by fine tuning of various process parameter. The present study revealed high metal tolerance ability of a soil fungus Cladosporium oxysporum AJP03 and its potential for extracellular synthesis of gold nanoparticles. The morphology, composition and crystallinity of nanoparticles were confirmed using standard techniques. The synthesized particles were quasi-spherical in shape with fcc packing and an average particle size of 72.32 ± 21.80 nm. A series of experiments were conducted to study the effect of different process parameters on particle size and yield. Biomass: water ratio of 1:5 and 1 mM precursor salt concentration at physiological pH (7.0) favoured the synthesis of well-defined gold nanoparticles with maximum yield. The as-synthesized nanoparticles showed excellent catalytic efficiency towards sodium borohydride mediated reduction of rhodamine B (2.5 × 10−5 M) within 7 min of reaction time under experimental conditions. Presence of proteins as capping material on the nanoparticle surface was found to be responsible for this remarkable catalytic efficiency. The present approach can be extrapolated to develop controlled and up-scalable process for mycosynthesis of nanoparticles for diverse applications.
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    Revisiting the architecture, biosynthesis and functional aspects of the plant cuticle: there is more scope
    (Elsiever, 2020-12-25) Panwar, Jitendra
    Having evolutionary significance in establishing colonization of terrestrial plants, cuticle occurs to act as a continuous shield over the plant epidermal cells, facilitating multifunctional communication passage between the plant and outer environment. Cuticle is a hydrophobic layer acting as a fencing between the aerial plant parts viz. primary stem, leaves, trichomes, flowers and fruits, and their external environment. The chemical nature and structure of cuticle may vary during various developmental and growth stages, as well as between various organs, genotypes, and species, depending on the environmental conditions. It is majorly composed of cutin and epicuticular wax depositions. In-depth understanding of the mechanism behind the cuticle biosynthesis remains to be unveiled. This review systematically discusses and sheds light on the structure and composition of cuticle, various genes, transcription factors and molecular pathways involved in the biosynthesis of cuticle, and how their regulation affect the plant health. Moreover, various functions of cuticle in terms of plant protection have been discussed.