Slide 1

Beauty and Sex: Flowering

Slide 2

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

Slide 3

Primary and secondary inflorescences

Slide 4

Vegetative and generative meristems Sepals Petals Stamens Carpels Leaves SAM Vegetative meristemGenerative meristem FM

Slide 5

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

Slide 6

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

Slide 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)

Slide 8

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

Slide 9

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

Slide 10

Photoperiodism is an external stimulus of flowering

Slide 11

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

Slide 12

Natural variation in Arabidopsis GermanyWest-Africa

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

Slide 14

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

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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

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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

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

Slide 18

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

Slide 19

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

Slide 20

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

Slide 21

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