Plant tissue culture 3

Plant tissue culture 3

Immobilized plant cell cultures enhance secondary metabolites because they:

Enhanced secondary product formation in encapsulated systems results from combination of stress alleviation and differentiation cues. Free suspensions expose fragile vacuolated cells to hydrodynamic forces that rupture tonoplast and trigger oxidative burst through phenylalanine ammonia lyase activation leading to browning. Entrapment in alginate or pectate gel dampens shear, maintains high local cell density that mimics tissue context, facilitates accumulation of signaling molecules such as oligosaccharides, and reduces growth rate, redirecting carbon flux from cell division to phenylpropanoid

Ref: Brodelius FEBS Lett 1979 immobilization metabolites; Tanaka J Ferment Bioeng 1993 shear protection; NCBI PMC3425142; Shuler Bioprocess Eng.

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Plant tissue culture 3

Cell suspension culture is mainly useful for:

Suspension cultures differ from callus grown on agar by continuous agitation ensuring homogeneous nutrient and gas distribution and removal of growth inhibitors. Inoculation of friable callus fragments into Erlenmeyer flasks on orbital shaker at 110 rpm disperses cells, creates single cells and small aggregates suitable for growth kinetic measurements, mutant selection, and bioreactor scale-up. Uniform cell size allows precise biomass estimation by packed cell volume and dry weight, enabling process control for large-scale production of cells for biochemical studies, somatic embryogenesis, art

Ref: Murashige & Skoog 1962 suspension; Street 1977 suspension methods; NCBI NBK26844 large scale; Phillips Plant Cell Culture 2010 bioreactor.

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Plant tissue culture 3

Natural insecticide produced by plants is:

Natural insecticidal compounds evolved as plant chemical defense against herbivory. Among most successful botanical insecticides, pyrethrin extracted from dried flower heads of Chrysanthemum cinerariifolium shows rapid knockdown, low mammalian toxicity with LD50 greater than 1 g per kg, and biodegradability within sunlight. Active esters partition into insect nervous system lipophilic phase, bind sodium channel and cause tremors, paralysis, and death. Unlike systemic carbamate toxins or mammalian neurotoxins, pyrethrin action is contact based and reversible at sublethal doses but enhanced by s

Ref: Isman Annu Rev Entomol 2006 botanical insecticides; NCBI NBK20389 pyrethrins; Casida Environ Health Perspect sodium channel; Campbell plant defense.

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Plant tissue culture 3

Vincristine and Vinblastine belong to:

Catharanthus roseus produces complex dimeric alkaloids via coupling of vindoline derived from tabersonine and catharanthine moieties through peroxidase α-3′,4′-anhydrovinblastine synthase. Resulting vinblastine and vincristine contain indole and dihydroindole units fused through intricate polycyclic framework bearing basic nitrogen essential for biological activity. They disrupt mitosis by specifically binding at vinca site on β-tubulin, preventing microtubule polymerization, arresting cells at metaphase, and inducing apoptosis through JNK pathway. Clinical importance in chemotherapy of childh

Ref: van Der Heijden Curr Med Chem 2004 Catharanthus alkaloids; NCBI NBK21154 indole alkaloid; Cragg Nat Prod Vinca; PubMed 15075446.

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Plant tissue culture 3

Pyrethrin is classified as:

Pyrethrin refers to mixture of six esters: pyrethrin I and II, cinerin I and II, jasmolin I and II, all sharing chrysanthemic acid monoterpene backbone esterified to rethrolone alcohol. Synthesis starts from dimethylallyl pyrophosphate via methylerythritol phosphate pathway in plastids of secretory trichomes of Tanacetum cinerariifolium flowers. Chemical skeleton built from five-carbon isoprene units classifies them as monoterpenoids, distinct from nitrogenous alkaloids or flavonoid phenylpropanoids. Insecticidal activity stems from binding to voltage-sensitive sodium channel IIS4-S5 linker, d

Ref: Casida & Quistad Pyrethrum Flowers 1995; NCBI CID 5281555 pyrethrin terpenoid; Crombie Pestic Sci 1999; Taiz secondary metabolites Ch 13.

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Plant tissue culture 3

Immobilization of plant cells helps in:

Plant cell suspension bioreactors generate hydrodynamic stresses from Rushton turbine agitation and aeration bubbles bursting at surface. Large vacuolated cells with thin primary wall shear more readily than microbial cells, leaking phenolics that cause browning and viability loss. Immobilization in calcium alginate beads of 2 to 4 mm diameter forms porous hydrogel matrix where cells entrap as microcolonies, shielding them from direct impeller impact and reducing turbulent eddies. Diffusion of nutrients and oxygen through beads sustains metabolism while preventing cell washout in perfusion mod

Ref: Brodelius Tibtech 1985 immobilized cells; Fowler Crit Rev Biotech 1986 shear; NCBI PMC3566382 alginate encapsulation; Yeoman Plant Cell Culture bioreactor.

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Plant tissue culture 3

hpt gene provides resistance against:

Hygromycin B blocks translation elongation through interference with ribosomal translocation step on 80S plant ribosomes. Bacterial gene hpt from Escherichia coli encodes 341 amino acid phosphotransferase that uses ATP to phosphorylate C-4 hydroxyl of destomic acid moiety of antibiotic, creating inactive phospho derivative that cannot occupy decoding site. Expression cassette includes CaMV 35S promoter and terminator for constitutive high expression in plant cytosol. Enzyme kinetics show high affinity for hygromycin but not kanamycin or gentamicin, providing specific resistance profile. Select

Ref: Gritz & Davies Gene 1983 hpt mechanism; Herrera-Estrella Nature 1983 marker; NCBI NBK21414 phosphotransferase; PubMed 1848829 review.

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Plant tissue culture 3

Selective agent commonly used in hairy root culture is:

Effective recovery of transformed roots requires stringent chemical selection distinguishing transgenic from non-transformed background. Hygromycin B, aminoglycoside antibiotic, inhibits protein biosynthesis by stabilizing tRNA-ribosome interaction causing misreading. Plant cells are highly sensitive, with lethal concentration around 20 mg per liter for many dicots. Transformation vectors carry hpt gene under NOS promoter encoding hygromycin phosphotransferase that phosphorylates antibiotic hydroxyl group, preventing ribosome binding. Co-transformation with Ri T-DNA and binary vector results i

Ref: Beck Gene 1982 hpt hygromycin; Waldron Plant Mol Biol 1985; NCBI NBK131103 markers; Jefferson Plant Cell Rep 1987 hygromycin hairy root selection.

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Plant tissue culture 3

Hairy root cultures are mainly used for:

Differentiated roots possess endodermis, pericycle, and organized transport tissues that compartmentalize biosynthetic pathways and sequester toxic end products safely in vacuoles. Hairy root cultures preserve this organization while displaying exponential growth in hormone-free liquid, combining advantages of organized tissue and microbial-like scalability. Many pharmaceuticals like atropine, scopolamine, withanolides, and tanshinones are synthesized primarily in root cortex and stored in vacuoles, so root cultures maintain expression of pathway genes including putrescine N-methyltransferase

Ref: Guillon Curr Opin Plant Biol 2006 metabolites; Srivastava Biotechnol Adv 2007; NCBI PMC3644105 hairy root factories; PubMed 17270743.

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Plant tissue culture 3

Hairy roots show which characteristic?

Phenotype of transformed roots reflects activity of rol genes integrated into nuclear genome. rolA, rolB, rolC alter auxin perception and secondary metabolism. Roots exhibit lack of strong positive geotropism, grow plagiotropically or ageotropically on agar, and display prolific lateral branching due to diminished apical dominance and enhanced pericycle activation. Branch tips are covered with dense root hairs, increasing surface area. Growth occurs without exogenous auxin on hormone-free medium, showing hormone autotrophy, and biomass accumulation is rapid, doubling every 2 to 3 days in liqui

Ref: Nilsson 1997 rolB auxin sensitivity; Casanova Trends Plant Sci 2005 morphology; NCBI NBK21344; https://doi.org/10.1016/j.tplants.2005.08.004 hairy root branching review.

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Plant tissue culture 3

Hairy root inducing plasmid is called:

Agrobacterium plasmids determine disease phenotype. Ti plasmid, tumor-inducing, contains T-DNA with iaaM, iaaH, and ipt genes overproducing auxin and cytokinin, causing undifferentiated gall. Ri plasmid, root-inducing, carries TL and TR T-DNA regions in agropine strains; TL harbors rol cluster essential for hairy root syndrome and TR carries auxin genes and agropine synthesis. Virulence region mediates T-strand excision and transfer via type IV secretion. Upon integration, rol gene expression modifies host signaling, stimulating root proliferation rather than callus. Laboratory disarmed Ri vec

Ref: White & Nester J Bacteriol 1980 Ri structure; Nilsson & Olsson Physiol Plant 1997 rol; NCBI NBK21414 Ti vs Ri; https://www.ncbi.nlm.nih.gov/books/NBK21414/

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Plant tissue culture 3

Hairy root cultures are induced by infection with:

Hairy root syndrome originates when wounded dicot tissue is invaded by soil bacterium carrying root inducing plasmid. Transfer of T-DNA segment harboring rolA, rolB, rolC, rolD loci plus opine synthesis genes into host chromosome rewires hormone balance. rolB encodes tyrosine phosphatase increasing auxin sensitivity, rolC cytokinin glucosidase adjusting growth, together triggering extensive adventitious root emergence directly from callus. Roots grow plagiotropically, highly branched, hormone independent, and genetically stable for decades. In contrast Agrobacterium tumefaciens produces crown

Ref: Chilton Nature 1982 Ri plasmid; Tepfer PNAS 1984 hairy root; NCBI NBK21344 rol genes; PubMed 17302573 hairy root review 2014.

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