Abstract
In plants, transport mediated by the PINFORMED (PIN) family of auxin efflux carriers helps create gradients on which many developmental processes depend. Current models suggest that Arabidopsis PIN1 has two concurrent functions during leaf initiation: 1) concentrating auxin to create local maxima in the meristem epidermis, and 2) transporting auxin away from the epidermal maxima and into the internal tissues. The resulting auxin gradient is required for leaf initiation and vein patterning. I identified an angiosperm PIN clade placed sister to PIN1, here termed Sister-of-PIN1 (SoPIN1), that has likely been lost within the Brassicaceae, including in Arabidopsis, but remains in all other angiosperms sampled. I also identify a conserved duplication of PIN1 to create PIN1a and PIN1b within the grasses. I used live-cell imaging and immuno-localization to characterize the expression and localization of SoPIN1, PIN1a and PIN1b members in both maize and Brachypodium. SoPIN1 expression is highest in the epidermis and is consistently oriented toward areas where the DR5 auxin reporter is highly expressed, suggesting that SoPIN1 functions in the creation of auxin maxima. PIN1a and PIN1b localization, largely absent from the epidermis and oriented rootward in the internal tissues, suggests that these PIN proteins transport auxin after maxima formation during the canalization of leaf and stem veins. These data support the functional division of PIN proteins into maxima creation and canalization modes. In addition, the loss of SoPIN1 within the Brassicaceae suggests that PIN1 in this group may be unique amongst the angiosperms in its ability to dynamically switch between these two functional modes. I then provide a model for how the PIN1a/PIN1b duplication in the lineage leading to the grasses may relate to the novel morphological and anatomical characteristics found in monocot plants. Finally, I summarize some preliminary PIN knockdown experiments that suggest a role for PIN mediated patterning in apical dominance, meristem maintenance and leaf proximal/distal patterning.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 10
Claim · model-written summary
SoPIN1 remains in the angiosperms sampled other than the Brassicaceae, where it was likely lost
- Taxon
- angiospermsMagnoliopsidae1
- Gene
- SoPIN1e1
- Outcome
- remains in all other angiosperms samplede1
Verbatim
e1“I identified an angiosperm PIN clade placed sister to PIN1, here termed Sister-of-PIN1 (SoPIN1), that has likely been lost within the Brassicaceae, including in Arabidopsis, but remains in all other angiosperms sampled”
Claim · model-written summary
PIN1 duplicated into PIN1a and PIN1b as a conserved feature within the grasses
Verbatim
e2“a conserved duplication of PIN1 to create PIN1a and PIN1b within the grasses”
Claim · model-written summary
SoPIN1 expression is highest in the epidermis of maize and Brachypodium and oriented toward DR5 auxin reporter maxima
- Taxon
- maize and Brachypodium
Zea mays
Brachypodiume4 - Organ / stage
- epidermise3
- Gene
- SoPIN1e3
- Outcome
- SoPIN1 expressione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“SoPIN1 expression is highest in the epidermis and is consistently oriented toward areas where the DR5 auxin reporter is highly expressed”
e4“in both maize and Brachypodium”
Claim · model-written summary
SoPIN1 may function in the creation of auxin maxima in maize and Brachypodium
- Taxon
- maize and BrachypodiumZea maysBrachypodiume4
- Gene
- SoPIN1e5
- Outcome
- creation of auxin maximae5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“suggesting that SoPIN1 functions in the creation of auxin maxima”
e4“in both maize and Brachypodium”
Claim · model-written summary
PIN1a and PIN1b localization is largely absent from the epidermis and oriented rootward in the internal tissues
- Taxon
- maize and BrachypodiumZea maysBrachypodiume4
- Organ / stage
- epidermise6
- Gene
- PIN1a and PIN1be6
- Outcome
- PIN1a and PIN1b localizatione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“PIN1a and PIN1b localization, largely absent from the epidermis and oriented rootward in the internal tissues”
e4“in both maize and Brachypodium”
Claim · model-written summary
PIN1a and PIN1b may transport auxin after maxima formation during canalization of leaf and stem veins
- Taxon
- maize and BrachypodiumZea maysBrachypodiume4
- Gene
- PIN1a and PIN1be6
- Outcome
- canalization of leaf and stem veinse7
- Qualifier
- after maxima formatione7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“suggests that these PIN proteins transport auxin after maxima formation during the canalization of leaf and stem veins”
e6“PIN1a and PIN1b localization, largely absent from the epidermis and oriented rootward in the internal tissues”
e4“in both maize and Brachypodium”
Claim · model-written summary
The data support a functional division of PIN proteins into maxima creation and canalization modes in grasses
Verbatim
t0“Auxin-transport mediated patterning in the grasses”
e0“These data support the functional division of PIN proteins into maxima creation and canalization modes”
Claim · model-written summary
Loss of SoPIN1 in the Brassicaceae may make PIN1 unique among angiosperms in switching between auxin transport modes
- Taxon
- BrassicaceaeBrassicaceaee0
- Gene
- PIN1e0
- Outcome
- ability to dynamically switch between these two functional modese0
Verbatim
e0“the loss of SoPIN1 within the Brassicaceae suggests that PIN1 in this group may be unique amongst the angiosperms in its ability to dynamically switch between these two functional modes”
Claim · model-written summary
The PIN1a/PIN1b duplication in the grass lineage may relate to novel morphological and anatomical characteristics of monocot plants
Verbatim
e0“a model for how the PIN1a/PIN1b duplication in the lineage leading to the grasses may relate to the novel morphological and anatomical characteristics found in monocot plants”
Claim · model-written summary
Preliminary PIN knockdown experiments suggest a role for PIN-mediated patterning in apical dominance, meristem maintenance and leaf patterning in grasses
Verbatim
t0“Auxin-transport mediated patterning in the grasses”
e1“some preliminary PIN knockdown experiments that suggest a role for PIN mediated patterning in apical dominance, meristem maintenance and leaf proximal/distal patterning”