Q.(a) List out the applications of plant tissue culture. OR

(a) Plant tissue culture applications range from clonal propagation and disease-free plants to synthetic seeds, haploid breeding, somatic hybridisation and transformation; (b) epiphytes are support-only, non-parasitic plants with root, stem and leaf adaptations for absorbing atmospheric moisture.

(a) Applications of plant tissue culture

1. Micropropagation (clonal propagation): mass, rapid, true-to-type multiplication of genetically superior or ornamental plants.
2. Production of disease (virus)-free plants: meristem-tip culture is used to obtain plants free of viral infection, since the actively dividing meristem is usually free of virus particles.
3. Germplasm conservation: tissue/cell cultures and cryopreservation techniques allow long-term storage and conservation of valuable or endangered plant genetic material in a small space.
4. Haploid production: culturing anthers or pollen (anther/microspore culture) yields haploid plantlets, which after chromosome doubling give completely homozygous diploid lines quickly -- greatly speeding up plant breeding programmes.
5. Somatic hybridisation: fusing protoplasts (cells with the wall removed) from two different, sexually incompatible species produces hybrid cells/plants, overcoming natural barriers to cross-breeding.
6. Production of secondary metabolites: cell suspension cultures can be used to produce valuable plant-derived chemicals (medicinal compounds, dyes, flavours) in bioreactors, independent of field cultivation.
7. Synthetic seed production: somatic embryos produced in culture are encapsulated to make artificial (synthetic) seeds.
8. Embryo rescue: hybrid embryos from wide (interspecific/intergeneric) crosses that would normally abort in the seed are rescued and grown in culture to obtain the hybrid plant.
9. Genetic transformation: tissue culture provides the regenerable cells/tissues needed to produce and multiply genetically transformed (transgenic) plants.

(b) Epiphytes and their morphological adaptations

Epiphytes are plants that grow attached to the surface of another plant (usually a tree), using it purely for physical support and anchorage, without being parasitic (they do not derive nutrients from the host's tissues). They are especially common in humid tropical and subtropical forests, obtaining their water and mineral nutrients from the surrounding humid air, rainwater, and accumulated organic debris. Examples include many orchids, ferns, mosses, and bromeliads such as Tillandsia.

Morphological adaptations that allow epiphytes to survive without soil contact:

1. Velamen-covered aerial roots: many epiphytic orchids have specialised aerial roots covered by velamen, a spongy, multi-layered epidermal tissue that rapidly absorbs and stores atmospheric moisture and dissolved nutrients. …