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DTSTAMP:20260424T143336Z
UID:1756724400@ist.ac.at
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DESCRIPTION:Speaker: David Babic\nhosted by Kimberly Modic\nAbstract: Arabi
 dopsis embryo has long served as a model system for understanding how plan
 t body patterning and axis establishment arise. Previous work established 
 that auxin flows\, directed by polar transport and reinforced by local bio
 synthesis\, underpin axes formation\, while recent studies suggest that ma
 ternal tissue\, membrane composition and surface receptor signaling add fu
 rther regulatory layers. In this thesis\, we dissect the layers of auxin-m
 ediated processes which guide plant embryonic and post-embryonic developme
 nt. We review methodological advances that allow the embryo to be imaged a
 nd studied. These tools offer exciting venues for future addressing of out
 standing research questions. Furthermore\, we dissect the contribution of 
 maternal auxin for early embryo patterning. Targeted auxin scavenging in t
 he integuments lowers the hormone reaching the proembryo\, destabilizes PI
 N7 in the suspensor and weakens the initial apical maximum. The resulting 
 deficit dampens downstream embryonic auxin biosynthesis\, as well as auxin
  flow towards the root pole\, indicating that maternally provided auxin co
 ntrols auxin flows in the embryos on a larger scale than previously unders
 tood. Intriguingly\, we uncover a prolonged gametophytic maternal effect m
 ediated by the receptor-like kinases TMK1 and TMK4. Reciprocal crosses and
  promoter-reporter analyses show that these genes are transcribed preferen
 tially from the maternal genome in both embryos and seedlings. Loss of mat
 ernal TMK activity arrests embryos\, affects seedling development and pers
 ists into adult growth\, indicating that parental imprinting shapes develo
 pment beyond fertilization and early embryogenesis. Finally\, we describe 
 the role of very-long-chain fatty acids and membrane composition on PIN pr
 oteins and their auxin-induced relocalization. Disruption in this lipid me
 tabolism triggers widespread patterning errors.Together\, these results re
 position early plant patterning as a hierarchical cascade that begins with
  maternal auxin\, gets amplified by auxin transport and biosynthesis\, pot
 entially modulated by maternal receptor signaling and could ultimately be 
 gated by the biophysical properties of the membrane. By integrating auxin 
 supply\, genetic imprinting and lipid-dependent trafficking into a single 
 narrative\, this thesis helps shifting the approach of viewing the embryo 
 as an autonomous unit to regarding it as a dynamic system\, continuously s
 culpted by its maternal context.
LOCATION:Sunstone Bldg / Ground floor / Big Seminar Room B / 63 seats (I23.
 EG.102) \, ISTA
ORGANIZER:
SUMMARY:David Babic: Thesis Defense: Mechanisms of auxin-mediated early emb
 ryogenesis in Arabidopsis thaliana
URL:https://talks-calendar.ista.ac.at/events/5946
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