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
phb-1d and phv-1d
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
miRNAs
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?
abaxial
How does the miRNA work?
it restricts the the expression of PHB in the adaxial domain
How does phb-1d 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?
Photoperiod
temperature
Photoperiod
daily recurring patter of light and dark periods
What are the 3 types of photoperiodism?
1. Day-neutral
2. Short-day
3. Long-day
Short-day plants
require short days and long nights
Long-day plants
require lond days and short nights
Obligate
require either a short day or long night
Facultative
cant flower even if it does not have a short day/long day
Bunning Model
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
Florigen
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
florigen
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