2- Morphogenesis in fruit tree species

Question 1

Please define In vitro morphogenesis

Answer 1

• Process of ex novo differentiation of well-organized structures starting from a plant explant (entire organs or part of them) or from callus
• From embryos → Somatic embryogenesis
• Or from Different Organs (Roots, Shoots,Floral Structures) →Organogenesis

Question 2

What´s the difference between direct and indirect morphogenisis?

Answer 2

• Morphogenesis: The neo-formation of well-organized structures can origin:

1. DIRECT: from explant tissues
2. INDIRECT: from callus produced by explants

Question 3

What´s a callus?

Answer 3

1. CALLUS is an amorphous aggregate of cells of variable size and irregular shape
2. callus cells are dividing untidily for a certain time period
3. Callus can be easily separated from the tissues from which it originates
4. Callus can proliferate on specific culture media: Solid or Liquid (Cell suspension culture)

Question 4

What´s the difference between embryogenesis and organogenesis?

Answer 4

Morphologic traits

• Embryogenesis: presence of two meristematic poles in the advanced developmental stages of somatic embryos (shoot and root apexes)
• Organogenesis: presence of one meristematic pole)

Histology studies

• Embryogenesis: presence in somatic embryos of closed vascular tissues (procambial traces lack connections with the explant or callus from which they were originated)
• Organogenesis: connection of the vascular system with those of explant or callus from which they were originated

Biochemical studies

• Embryogenesis: Somatic embryos present embryo-specific protein

Question 5

What are potential applications for In vitro morphogenesis?

Answer 5

1. Regeneration of plants identical to the originary genotype

• clonal propagation
• germplasm preservation

2. Production of new genetic variability and epigenetics

• production of variant clones
• transgenosis
• somatic hybrids (protoplast somatic hybridation) -
• ploidy level variation (haploids)

Question 6

What are the stages in Morphogenesis?

Answer 6

1. “Competence” stage
2. “Determination” stage (reversible)
3. “Development and expression” stages (not-reversible)

Question 7

What are the factors influencing morphogenesis efficiency?

Answer 7

1. Genotype (Natural attitude of each species to undertake one or more morphogenetic processes)
2. Explant (depending on the final aim)
3. Culture conditions