1. Beauty and Sex: Flowering

2. Flowers are derived from the process of transition from
vegetative to generative meristems

3. Primary and secondary inflorescences

4. Vegetative and generative meristems
Carpels
Petals
Leaves
Stamens FM
SAM
Sepals
Vegetative meristem
Generative meristem

5. Floral organs are initiated from the floral meristem in concentric whorls
Meristem identity genes → floral organ identity genes → cadastral genes

6. Floral organ identity genes are responsible for reproductive organ formation
No sepals/petals No petals/stamens No stamens/pistils

7. Flowering is regulated by internal and external stimuli
Juvenile to adult phase transition is characterized by morphological and physiological characteristics
English Ivy (Hedera helix)

8. Juvenile to adult transition requires competence (adult vegetative phase), determination and expression

9. Photoperiodism is an external stimulus of flowering
Short-day, long-day and day-neutral plants
Night break inhibits flowering
Night break of sufficient duration induces flowering

10. Photoperiodism is an external stimulus of flowering

11. West Lafayette Plants are adapted to day-length at different latitudes
Phytochromes and cryptochromes are the photoreceptors that regulate flowering
West Lafayette

12. Natural variation in Arabidopsis
Germany
West-Africa

13. Plants are adapted to day-length at different latitudes
Phytochromes and cryptochromes are the photoreceptors that regulate flowering
Ler
Ler
Cvi
Cvi

14. Plants track time with their circadian clock
Periodic rhythm of plant processes that is regulated by an internal timepiece

15. CO (CONSTANS) and FT (FLOWERING LOCUS T ) are regulators of flowering in Arabidopsis (long-day plants)
CO expression is clock controlled
CO protein accumulation is regulated by proteolysis

16. Similar homologs Regulate flowering in short-day plants
Rice (short-day plant) - Heading-date1 (Hd1) = CO and Heading-date3 (Hd3) = FT
However, Hd1 inhibits Hd3 activation of flowering

17. FLC negatively regulates flowering
Vernalization is required before some plants are responsive to photoperiodic-induced floral transition
FLC negatively regulates flowering

18. FLC negatively regulates flowering
Vernalization is required before some plants are responsive to photoperiodic-induced floral transition
FLC negatively regulates flowering

19. Florigen is the biochemical signal for flowering
Plant Biology (2010) Smith et al.

20. Zeevart (2007) Taiz and Zeiger Web Essay 25.2
FLOWERING LOCUS T

21. Integration of flowering stimuli
Plant Biology (2010) Smith et al.