LFY
Inflorescence
TF1
meristem
Floral meristem
The discovery of photoperiodism
Garner and Allard (1920’s)
Soybeans (Glycine max) planted over a three-month
period all flowered about the same time
LEAFY;
• LFY, FUNCTIONS IN: chromatin DNA binding, transcription factor activity, sequence-specific DNA binding; INVOLVED IN: flower development, maintenance of inflorescence meristem identity, response to gibberellin stimulus, gibberellic acid mediated signaling; LOCATED IN: nucleus;
• Genes (flowering-time genes and floral identity genes)
• Light (photoperiod) • The biological clock • Temperature • Hormones
Floral meristem
Flowering-time genes
2. Convert inflorescence meristem to floral meristem (terminal, flowers)
SC: stem cell P: organ primordia Se: sepal
Factors regulating the transitions
Vegetative meristem Inflorescence meristem
• EXPRESSED IN: shoot apex, leaf whorl, embryo, flower, seed; EXPRESSED DURING: 7 growth stages;
Factors regulating the transition to reproduction
EMF
Vegetative meristem
leafy (lfy): produce more
inflorescences, delayed flowering
tfl1
• [FUNCTION] Controls inflorescence meristem identity and is required for maintenance of a indeterminate inflorescence. Prevents the expression of 'APETALA1' and 'LEAFY'. Also plays a role in the regulation of the time of flowering in the long-day flowering pathway. May form plexes with phosphorylated ligands by interfering with kinases and their effectors] Expressed below the apical dome of inflorescence and coflorescence meristems, and in inflorescence stem. Weakly expressed in vegetative phase from day 2 or day 3. Increased expression after mitment to flowering from day 7 on.
Plant Reproduction
Zichao Mao
Life cycle of plant
Plant Reproduction • Transition to reproduction • Flower organ development • Gametogenesis and fertilization
Transition to reproduction
Flower
Inflorescence
Vegetative phase
Reproductive phase
Productansitions in Arabidopsis
1. Convert SAM （ Shoot Apical Meristem) to inflorescence meristem (infinite, making lateral organs)
Many more experiments were followed: • Eliminate a variety of environmental conditions:
Nutrition, temperature, and light intensity • Relative length of day and night decides the
Flower (from Floral meristem)
Inflorescence (from Inflorescence meristem)
Mutations in floral identity genes
terminal flower 1 (tfl1):
Convert the inflorescence meristem to the flower meristem.
affecting the transition of vegetative growth to reproductive growth
WT
emf1
emf2
embryonic flower
Floral identity genes
affecting formation of inflorescence and floral meristems