REGULATION and GENE EXPRESSION in PLANT DEVELOPMENT Flashcards
______ connect genetics and development by establishing the chain of events from gene activity to morphological differences.
Hierarchies of gene interactions dictate the size, shape, and structure of plants through coordinated regulation.
Regulatory genes
Which are italicized? Gene symbols or proteins?
Genes
By the ____ of embryogenesis (approximately four days after fertilization), all principal elements of the plant body are established.
_____ of the hormone auxin begins early and is crucial for defining the embryo’s main axis and central vasculature.
heart stage
Apical-to-basal transport
Auxin Flux and Plant Development
Key Components:
_____ DNA sequences in the promoters of auxin-inducible genes.
_____ A family of proteins that bind to AREs and regulate gene expression.
_____ Transcriptional repressors that interact with ARFs to inhibit gene expression.
ARE (Auxin Response Element):
ARF (Auxin Response Factor):
Aux/IAA
Auxin Flux and Plant Development
Mechanism of Action:
Auxin as a _____:
Auxin binds to the TIR1/AFB protein complex, facilitating the interaction between Aux/IAA proteins and the SCF-type E3 ubiquitin ligase complex.
______:
Components: Skp1, Cullin1 (Cul1), Rbx1, and the TIR1/AFB protein.
The complex tags Aux/IAA proteins with ubiquitin (Ub) via a cascade involving E1 (ubiquitin-activating enzyme) and E2 (ubiquitin-conjugating enzyme).
Molecular Glue
SCF E3 Ubiquitin Ligase Complex
Auxin Flux and Plant Development
Mechanism of Action:
Degradation of Aux/IAA:
Polyubiquitinated Aux/IAA proteins are targeted for degradation by the _____, removing repression from ARE-containing promoters.
Activation of Transcription:
Once Aux/IAA repressors are degraded, ARFs can activate transcription of _____, leading to various developmental responses.
26S proteasome
auxin-inducible genes
Auxin Flux and Plant Development
_____ indicates the sites of organ initiation and development, mediated by the dynamic localization and function of PIN proteins.
Auxin maxima
Auxin Flux and Plant Development
_____ are auxin efflux carriers that facilitate the directional transport of auxin across cells, establishing auxin gradients essential for plant development. Predicts where auxin will be.
____ is localized to the basal membrane of inner cells in the _____, mediating ____
_____ localizes to the_____of suspensor cells and reportedly triggers weak expression of a _____ in the proembryo.
PIN proteins
PIN1
proembryo
basal-to-apical transport
PIN7
apical membranes
DR5 reporter gene
Auxin Flux and Plant Development
_____ postulates that auxin acts to polarize its own transport, this canalization is an important part of the mechanism that underlies coordinated tissue polarization
_____ constructs are synthetic auxin-responsive promoters used to visualize transcriptional responses to auxin. They help determine the positions of auxin perception maxima, essential for studying auxin’s role in organogenesis and cellular differentiation.
Canalization hypothesis
DR5: Reporter Gene
Key Genes and Pathways in Plant Development:
regulate cell division and expansion, particularly in (maintaining the stem cell population) in the shoot apical meristem (SAM).
WOX Family and WUSCHEL (WUS)
Key Genes and Pathways in Plant Development:
regulates membrane trafficking (endosomal recycling) of auxin-efflux carrier PIN1 essential for the correct (localization of PIN proteins) and therefore proper auxin distribution and embryonic pattern formation.
points to auxin drainage
alterthe asymmetric division of the zygote and interfere with the formation of distinct apical-basal regions in the developing embryo.
regulates the formation of vesicles in membrane trafficking
GNOM Gene
Key Genes and Pathways in Plant Development:
_____ pathway plays a major role in (establishing different cell fates) post-zygotic division, influencing basal cell lineage towards (forming the suspensor)
_____ iestablishing different cell fates after the first zygotic division.
YODA (YDA)
MAPK kinase gene
Key Genes and Pathways in Plant Development:
_____ may play a role complementary to YDA and promotes normal development of the apical cell into a proembryo
Auxin
Key Genes and Pathways in Plant Development:
_____ Works within the YDA pathway to determine suspensor identity
its protein in the leaf epidermis is sufficient to activate YDA-dependent signaling
SHORT SUSPENSOR (SSP)
Key Genes and Pathways in Plant Development:
____ a transcription factor responsive to auxin, is required for primary root formation and vascular development.
Stabilizing mutations in____can be suppressed by the overexpression of MP
Aux/IAA proteins act as inhibitors of MP
It may directly activate transcription of PIN1.
MONOPTEROS (MP) Gene
Apical and Basal:
____ and _____mark the upper-tier cells between the 8-cell
______
mark the lower-tier cells between the 8-cell
______ genes normal patterning of the apical domain
_____ involved in maintenance of shoot fates
WOX2 and CUC3
PLETHORA 1 (PLT1)
GURKE/PASTICCINO (GK/PAS)
TOPLESS (TPL)
Globular Stage
______ Promotes central or adaxial cell fates.
Dominant alleles resistant to microRNA increase the size of the embryonic SAM and promote adaxial characters.
____ and ____
Promote central or adaxial cell fates.
Expressed in the center of the upper tier and the adaxial sides of developing cotyledons.
____ and _____
Define the peripheral domain.
Promote abaxial or peripheral cell fates.
______
Binds microRNAs and mediates the degradation of target transcripts.
Enhances effects of rev loss-of-function alleles.
PHB (PHABULOSA)
PHV (PHAVOLUTA) and REV (REVOLUTA)
KANADI (KAN) and YABBY (YAB)
ARGONAUTE (AGO)
Regulation of Leaf Development:
______
Promote abaxial cell fates and help maintain leaf bilateral symmetry.
KAN1 is expressed in the peripheral cells of the lower tier and the abaxial side of cotyledon primordia.
_____
Detected at the late globular stage, marks the abaxial side of cotyledon primordia.
Promotes blade outgrowth in lateral organs.
_____
Expressed in lateral organs and promotes differentiation by repressing meristematic characteristics.
KANADI Genes
FILAMENTOUS FLOWER (FIL)
AS1 (ASYMMETRIC LEAVES1)
Medial Stage
_____
A homeodomain gene of the KNOTTED family.
Establishes medial and lateral gene expression domains at the late globular stage.
Prior to cotyledon outgrowth, redirects auxin flux towards incipient primordia.
_____
Mediates redistribution of PIN proteins from basal to apical localization.
SHOOTMERISTEMLESS (STM)
PID (PINOID)
_______ Establish expression domains defining the medial domain separating cotyledon primordia.
Repress cell proliferation and differentiation to generate a boundary.
Initiate expression of STM in the medial domain.
CUP-SHAPED COTYLEDON (CUC) Genes (CUC1, CUC2, CUC3)
Hypocotyl and Embryonic Roots
______ Encode AP2 class transcription factors essential for QC specification and stem cell activity.
Expression confined to provascular cells above the hypophysis.
______ Regulates asymmetric cell division and radial organization of the root.
Required for stem cell maintenance in the root meristem.
_______
Works with SCR to maintain the root meristem.
PLETHORA (PLT1, PLT2) Genes
SCARECROW (SCR)
SHORT-ROOT (SHR)
Hypocotyl and Embryonic Roots
_____ Required for root meristem formation.
Affects hypophysis derivatives and limits auxin responses to actively dividing cells.
_____ Involved in maintaining adjacent tissue initials in an undifferentiated state during QC function.
_____ Involved in specifying hypophysis fate and root development.
HOBBIT (HBT)
RETINOBLASTOMA-RELATED (RBR)
WOX (WUSCHEL-related homeobox) Genes (WOX5, WOX8, WOX9/STIMPY)
