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#plant tissue culture

56 public questions tagged with this topic.

Which plant tissue culture technique is used for large-scale plant propagation?

Micropropagation is used for large-scale production of genetically identical plants. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, physiology, human health and related concepts as per latest syllabus.

Which component in tissue culture media provides energy to growing plant lls?

Sucrose provides the energy required for the growth and development of plant lls in tissue culture media. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Structural Organisation in Animals and Frog, Topic: Tissues, skeletal and organ systems.

Which nutrient in plant tissue culture media provides energy for ll growth?

Sucrose provides the energy required for the growth and development of plant lls in tissue culture media. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Structural Organisation in Animals and Frog, Topic: Tissues, skeletal and organ systems.

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 liquid. Neoplasticity and genetic stability maintained over long term distinguish them from normal roots that require auxin for initiation. Recognition of high lateral branching as diagnostic marker helps differentiate hairy root cultures during selection and explains industrial interest for continuous secondary metabolite extraction in immersed bioreactors. Microscopic analysis reveals increased pericycle cell divisions and early lateral initiation, attributed to rolB mediated increase in auxin sensitivity and reduced expression of AUX/IAA repressors. Root hairs dense and elongated, increasing absorptive surface. Biomass productivity high because growth not dependent on external auxin supply. This highly branched phenotype exploited for rhizosphere interaction studies and secondary metabolite exudation.

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.

Friable callus is mainly used to initiate:

Texture of callus determines suitability for liquid systems. Compact nodular callus consists of tightly packed cells cemented by calcium pectate, resistant to dispersal. Friable type arises when pectin methylesterase activity reduces middle lamella cohesion, producing crumbly masses of loosely associated, highly vacuolated cells with large intercellular air spaces. Upon transfer to agitated liquid Murashige-Skoog medium containing 2,4-D, these fragments break easily into single cells and small aggregates under 100 micrometer diameter, forming homogeneous suspension. Such suspensions exhibit exponential growth, uniform nutrient uptake, and amenability to sieving and plating for single-cell cloning. They serve as source for protoplast isolation and bioreactor inoculum. Compact embryogenic callus retains cohesion and yields poor suspensions. Hence friable callus is specifically maintained and multiplied to initiate cell suspension cultures essential for secondary metabolite production and large-scale propagation. Size distribution analysis via hemocytometer shows friable callus yields high proportion of viable small clusters. Sieving through 250 micrometer mesh enriches for embryogenic units initiating suspensions. Maintenance requires regular subculture of friable clumps to prevent compacting. This physical property exploited in scale-up for bioreactor inoculum and somatic embryogenesis induction protocols.

Ref: Murashige & Skoog 1962 friable callus; Street Plant Tissue 1977 suspension initiation; Dodds & Roberts Experiments 4th ed; NCBI NBK26844 cell suspensions texture importance.

Habituation in callus culture refers to:

Normal plant cell proliferation requires exogenous auxin to activate S-phase genes and cytokinin to induce mitotic cyclins. Habituation denotes acquired ability to divide without these supplements due to stable metabolic reprogramming. Prolonged culture selects variants overproducing cytokinins via isopentenyl transferase genes or auxins via YUCCA flavin monooxygenases, or mutations conferring constitutive signaling through type-B response regulators and auxin receptors TIR1. Epigenetic changes in promoter methylation lock these biosynthetic genes in active state, making trait heritable through mitosis but occasionally reversible. Habituated callus appears vigorous, proliferates on basal medium lacking hormones, yet often shows reduced capacity to form organized primordia because internal hormone ratio is unbalanced. Recognition of hormone independence as habituation explains why some callus lines become recalcitrant to regeneration despite optimal external hormone supplementation and require rejuvenation strategies. Transcript profiling of habituated lines reveals constitutive expression of cytokinin response regulators ARR and auxin biosynthesis genes, circumventing requirement for external supply. Such autotrophy often accompanied by loss of regenerative competence because high internal hormone levels inhibit organized meristem formation. Reversal attempted by culture on hormone-free medium with activated charcoal to adsorb residual regulators.

Ref: Gautheret 1955 habituation; Meins & Binns PNAS 1979 hormone autotrophy; Taiz Plant Physiology Ch 21 cytokinin autonomy; NCBI NBK218342 habituation concept review.

One method to reduce somaclonal variation is:

Minimizing dedifferentiation reduces accumulation of chromosomal instability. Callus phase involves disorganized rapid mitosis under influence of potent synthetic auxin, creating opportunities for endoreduplication, transposon mobilization, and methylation drift. Each additional subculture multiplies these errors. Direct regeneration circumvents callus by activating axillary meristems, adventitious shoot formation from epidermal cells, or direct somatic embryogenesis on explant surface using balanced cytokinin to auxin ratio. Because organized meristems divide less frequently and maintain tight cell cycle checkpoints, genome remains stable. Protocols for banana, sugarcane, and potato emphasize direct shoot tip multiplication without intervening callus, limiting time on 2,4-D containing induction medium. Supplemental measures include using young explants, low growth regulator concentrations, and minimal subculture cycles. Avoiding callus and employing direct organogenesis is therefore principal strategy to curtail somaclonal variation frequency. Shoot meristems maintain L1, L2, L3 layer integrity and functional WUSCHEL-CLAVATA feedback loop preserving stem cell niche, reducing replication errors. Use of cytokinin BAP at moderate concentration promotes direct bud break from axillary meristems. This approach avoids dedifferentiation induced genome shock, ensuring clonal fidelity essential for commercial production of elite genotypes.

Ref: Bhojwani & Razdan Plant Tissue Culture 2015 Ch 10 direct organogenesis; Thorpe In Vitro Embryogenesis; NCBI PMC7469045 reducing somaclonal variation; Murashige & Skoog direct regeneration.

Herbicide-resistant somaclonal variants are detected by:

Herbicide resistance is a positive selectable trait best confirmed through functional challenge. Somaclonal populations contain rare cells with modified target enzymes such as glyphosate-insensitive EPSP synthase, acetylated phosphinothricin via PAT, or amplified glutathione S-transferases conferring detoxification. Plating callus or cell suspensions onto medium supplemented with discriminating concentration of respective herbicide imposes lethal pressure, killing wild-type cells by blocking aromatic amino acid synthesis or glutamine synthetase, causing ammonia toxicity. Only resistant clones proliferate, form green microcalli, and regenerate shoots. Secondary confirmation involves leaf painting or whole-plant spray at field-equivalent doses. Gel electrophoresis and chromosome counting cannot predict tolerance because single-base substitutions may confer resistance. Thus inclusion of herbicide in culture medium provides direct, scalable in vitro selection system accelerating isolation of resistant variants for crop improvement without requiring immediate field trials. Concentration optimized through kill curve experiments determines LD90 for wild type. Resistant calli isolated show stable inheritance of tolerance after removal of herbicide, indicating genetic mutation rather than epigenetic adaptation. Secondary leaf disc assays and whole-plant spray trials validate resistance level, supporting utilization for crop improvement programs targeting herbicide tolerance.

Ref: Chaleff & Raytbauer Science 1985 herbicide selection; PubMed 24254045 in vitro selection; NCBI NBK131103 selection systems; Bhojwani herbicide resistance screening.

Somaclonal variants can be detected using:

Comprehensive identification of somaclones demands multi-level screening, since variation manifests from visible morphology to DNA sequence. Whole-plant evaluation in greenhouse notes leaf shape, plant height, flowering time, flower color, and vigor, providing first indication of off-types. Cytological examination extends analysis to nuclear level, measuring chromosome number, polyploidy, anaphase bridges, and micronuclei after fixation and acetocarmine staining of actively dividing root tips. Molecular level assessment employs electrophoretic tools: isozyme SDS-PAGE reveals altered enzyme mobility, while RAPD, AFLP, SSR, and ISSR produce DNA fingerprints detecting point mutations, transposon insertions, and methylation polymorphisms. Biochemical chromatography adds secondary metabolite profiling. No single method covers all classes, so integrating morphological scoring, microscopic karyotyping, and gel electrophoretic analysis provides robust quality control for clonal fidelity and efficient isolation of novel beneficial variants in commercial micropropagation pipelines. Integration of datasets using multivariate analysis improves discrimination of beneficial versus detrimental variation. Modern approaches also employ flow cytometry for ploidy and high-throughput sequencing for SNP detection, reinforcing concept that combined morphological, cytological, and electrophoretic methods provide complete spectrum assessment for quality assurance in micropropagation systems.

Ref: Bhojwani & Dantu Plant Tissue Culture Ch 12 detection; NCBI PMC403111 somaclonal markers; IntechOpen Molecular electrophoresis; https://www.ncbi.nlm.nih.gov/books/NBK218342/

Which is NOT a cause of somaclonal variation?

Causes of somaclonal variation encompass genetic epigenetic disruptions triggered by tissue culture environment, but pollination mechanism is unrelated because in vitro regeneration occurs without sexual fertilization. Authentic causes include gene mutations from replication errors under rapid division error prone repair under oxidative stress, chromosome number changes aneuploidy polyploidy due to spindle abnormalities c mitosis endoreduplication induced by culture hormones colchicine like effects, structural rearrangements translocations deletions from DNA strand breaks, activation of dormant transposable elements such as Ac Ds Mu or retrotransposons like Tos17 which excise insert causing insertional mutagenesis and genome shuffling, and epigenetic changes including altered cytosine methylation at CpG islands histone modifications regulating gene expression stability. Prolonged callus phase duration high 2,4-D concentration age of donor tissue and repeated subculture amplify variation frequency. Pollination mechanism describing self cross compatible outcrossing insect wind mediated pollen transfer belongs to sexual reproduction in field influencing seed set heterozygosity, not operating in axenic culture boxes where no pollinators pollen tubes or fertilization events occur, therefore cannot generate somaclonal variation observed among regenerants.

Ref: Kaeppler 2000 somaclonal causes transposons; NCBI causes methylation mutation.

Colchicine is used in plant tissue culture mainly to:

Colchicine is used in plant tissue culture mainly to induce polyploidy and chromosome doubling rather than as fusogen or wall digesting agent. Alkaloid isolated from Colchicum autumnale binds tubulin dimers preventing polymerization into microtubules forming mitotic spindle fibers during metaphase. Without functional spindle, sister chromatids fail to separate at anaphase, nuclear membrane reforms enclosing doubled chromosome complement leading to endoreduplication tetraploid or doubled haploid formation. Application involves treating haploid plantlets derived from androgenesis gynogenesis or diploid explants with aqueous colchicine 0.05 to 0.5 percent for few hours to few days often with DMSO enhancing penetration then washing thoroughly to remove residual toxicity. Resulting polyploids often exhibit larger cells organs increased vigor greater secondary metabolite production and restored fertility in doubled haploids homozygous at all loci valuable for breeding. Due to colchicine toxicity mutagenicity alternatives like oryzalin amiprophos methyl herbicides inhibiting microtubule organization at lower concentrations are increasingly used. Dosage optimization prevents chimerism aneuploidy and severe growth inhibition allowing recovery of stable polyploid lines after few subcultures.

Ref: Blakeslee & Avery 1937 colchicine polyploidy; Dhooghe et al., Plant Methods antimitotic.

Osmotic stabilizers such as mannitol are required to:

Osmotic stabilizers such as mannitol sorbitol glucose at 0.3 to 0.7 molar act as essential protectants preventing protoplast bursting after cell wall removal because wall normally provides mechanical resistance counterbalancing internal turgor pressure generated by high intracellular solute concentration. Without rigid wall plasma membrane alone insufficient to resist water influx driven by lower external water potential, protoplasts swell and lyse within minutes, destroying preparation. Non metabolizable sugar alcohol mannitol provides iso osmotic environment matching cell sap osmolarity about 0.5 osmolar measured by osmometer, maintaining spherical shape membrane integrity during enzymatic incubation and washing steps. Mannitol preferred over metabolizable sugars because it is not quickly consumed altering osmolarity and does not trigger unwanted metabolic pathways influencing division potential. Concentrations titrated slightly hypertonic initially causing gentle plasmolysis shrinking protoplast away from wall aiding enzymatic release, then gradually lowered after wall regeneration allowing expansion and division. Absence of stabilizer results in zero viable protoplast yield, highlighting critical role for maintaining viability during isolation culture fusion procedures underlying somatic hybridization and transformation workflows.

Ref: Kao & Michayluk 1975 osmotic stabilizer; Plant Cell Culture protoplast methods.