Applications of Biotechnology in Plant Breeding

1. Applications of Biotechnology inPlant Breeding Sadanand Dhekney, PhD University of Florida / IFAS Mid-Florida Research & Education Center Apopka, FL 32703

2. Limitations of Conventional Breeding • Extreme heterozygosity and pronounced inbreeding depression in plant species • F1 hybrid produced is of intermediate quality • Long juvenile period of sp. makes screening of new selections tedious and time consuming

3. Plant biotechnology What is plant biotechnology? Products on the market Benefits of biotechnology

4. Plant biotechnology A precise process in which scientific techniques are adopted to develop useful and beneficial plants.

5. Commercial variety New variety Desired gene Using plant biotechnology, a single gene may be added to the strand. (only desired gene is transferred) = (transfers) Desired gene Traditional plant breeding Commercial variety New variety Traditional donor DNA is a strand of genes, much like a strand of pearls. Traditional plant breeding combines many genes at once. (many genes are transferred) = X (crosses) Desired Gene Desired gene Plant biotechnology

6. What is Plant Tissue Culture? Totipotency Single cell has the ability to regenerate into a whole plant

7. What conditions do plant cells need to multiply in vitro? • Freedom from competition • Nutrients and removal of waste products • A controlled environment

8. Applications

9. Seed culture • Increasing efficiency of germination of seeds that are difficult to germinate in vivo • Precocious germination by application of plant growth regulators • Production of clean seedlings for explants or meristem culture

10. Embryo culture • Overcoming embryo abortion due to incompatibility barriers • Overcoming seed dormancy and self-sterility of seeds • Embryo rescue in distant (interspecific or intergeneric) hybridization where endosperm development is poor • Shortening of breeding cycle

11. Ovary or ovule culture • Production of haploid plants • A common explant for the initiation of somatic embryogenic cultures • Overcoming abortion of embryos of wide hybrids at very early stages of development due to incompatibility barriers • In vitro fertilization for the production of distant hybrids avoiding style and stigmatic incompatibility that inhibits pollen germination and pollen tube growth

12. Anther and microspore culture • Production of haploid plants • Production of homozygous diploid lines through chromosome doubling, thus reducing the time required to produce inbred lines • Uncovering mutations or recessive phenotypes

13. Organ culture Any plant organ can serve as an explant to initiate cultures

14. Shoot apical meristem culture • Production of virus free germplasm • Mass production of desirable genotypes • Facilitation of exchange between locations (production of clean material) • Cryopreservation (cold storage) or in vitro conservation of germplasm

15. Somatic embryogenesis • One major path of regeneration • Mass multiplication • Production of artificial seeds • As source material for embryogenic protoplasts • Amenable to mechanization and for bioreactors

16. Embryogenic Non - embryogenic Leaf explant Embryogenic callus Embryo development Embryogenic Culture System for Vitis Initiation from leaves on NB 2 medium (Gray, 1995)

17. Organogenesis • One major path of regeneration • Mass multiplication • Conservation of germplasm at either normal or sub-zero temperatures

18. Callus Cultures • In some instances it is necessary to go through a callus phase prior to regeneration via somatic embryogenesis or organogenesis • For generation of useful somaclonal variants (genetic or epigenetic) • As a source of protoplasts and suspension cultures • For production of metabolites • Used in in vitro selection

19. Stamen explant Callus formation from connective tissue Callus formation from filament tip Embryogenic callus Embryo development Embryo germination Initiation from Stamens and Pistils

20. In vitro mutagenesis • Induction of polyploidy • Introduction of genetic variability

21. Genetic transformation • Introduction of foreign DNA to generate novel (and typically desirable) genetic combinations Many different explants can be used, depending on the plant species and its favored method of regeneration as well as the method of transformation • Used to study the function of genes

22. Genetic Transformation System + Co-cultivate 48 h Callus induction medium Embryo explants Wash explants Agro culture Select transgenic embryos using GFP/NPT II system Embryo development medium Regenerate transgenic plants

23. Applications • Disease resistance • Insect resistance • Salinity tolerance • Heavy metals tolerance • Improved nutritional characteristics

24. More than 50 biotech food products have been approved for commercial use in the United States • Canola (5%) • Corn (21%) • Cotton (12%) • Papaya • Potato • Soybeans (62%) • Squash • Sugarbeets • Sweet corn • Tomato

25. Advantages & Limitations Advantages • Food quantity • Food quality • Eco friendly Limitations • Recent scientific advances • Tangible benefits may not be long term