Card Set Information
What are the two difference between stems and leafs
1. Stems are radially symmetrical
2. Stems are indeterminate
What are the two surfaces of leaves and which side are they one?
1. adaxial-top surface
2. abaxial-bottom surface
What are the 3 axis leafs can be divided into?
1. Proximodital-form base of leaf to tip
2. Adaxial/Abaxial-top to bottom
3. Centrolateral-from center of leaf to edge
time interval b/t the intitation of 2 successive leaf primordia
inititation of leaves with an angle between them of 137.5
What are the 3 steps in leaf intiation?
1. specifying of leaf founder cells in PZ
2. outgrowth of cell to form a bulge
3. morphogensis w/in leaf primodia to establish flat structure
T/F: existing leaf primordia prevent new leaf initiation at postions immediatly adjacent to them
Is Auxin required for leaf initation?
Which side of leaf primordia is adjacent to the meristem?
Which side of the leaf primordia points away from the meristem
Which side of the leaf do axillary meristems arise?
The polarity of adaxial-abaxial primordia involves a signal from where?
radialized leaves; loss of vascular polarity; loss of adaxial epidermis and palisade mesophyll(abaxial leaves)
radialized leaves; loss of abaxial cell types(adaxial leaves)
What two genes are the primary determinate of leaf polarity?
1. KAN for abaxial
2. PHB, PHV, REV for adaxial
responsible for abaxial polarity
PHB, PHV, REV
responsible for adaxial polarity
What are the 3 memebers of the KAN family, and which act partially redundant
KAN1, KAN2, KAN3
partially adaxial, reduced lamina expansion, floral organs adaxial
results in transformation of adaxial cell to abaxial cells, thin pointed cotelydons; lack of SAM and vascular tissue in the hypocotyl
III HD-ZIP gene family
PHB, PHV, REV
radialized and adoxail leaves; loss of abaxial cell types and radialized leaves
rev phb phv
seedlings has a single radialized and abaxialized cotlyedons and lack SAM
Describe the class III HD-ZIP proteins
Transcription factor which is divided into three domains: homedomain, leucine zipperm and sterol/lipid binding domain(START)
What does KAN repress
PHB like gene expression in the abaxial domain
What doe PHB/PHV/REV repress?
KAN gene expression in the abaxial domain
Signal from meristem____ PHB/PHV/REV___KAN__abaxial fate
----> , -----I ------->
PHB-like genes are regulated by what RNA
What are the two miRNAs
miR165 and miR166
What is the binding site for the miRNAs
START domain within the PHB mRNA
Which domain is the mRNA expressed in?
How does the miRNA work?
it restricts the the expression of PHB in the adaxial domain
mutants act in relation to miRNA
miRNA is not able to bind so PHB is not cleaved is expresssed thru out leaf primordia
What type of signals determine whetther the VM turns into IM
both internal and external signals
What are the 2 external siganls that determine the switch from VM to IM?
daily recurring patter of light and dark periods
What are the 3 types of photoperiodism?
require short days and long nights
require lond days and short nights
require either a short day or long night
cant flower even if it does not have a short day/long day
photoperiodic responses occur based on temperal co-occurance of an internal clock-regulated protein. in long day protein promotes flowers in short days regulator is a repressor of flowering
flower hormone that is expressed in the leaves and moves thru the phloem to the SAM which is promoted by CO
What does CO promote
What are the four pathways that control flowering in arabidopsis
1. photoperiodic=promotes in long days
2. autonomous= promoted by internal development signal
3. vernalization=promoted by exposure to cold
4. GA=promotes bu gibberillins
What do CO mutants do in realtion to flowering in long day