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Designing the Superplant: Increasing Lipid Signaling for Enhanced Phosphorus Uptake

Jedemark, Louise LU (2021) KBKM05 20202
Pure and Applied Biochemistry
Theoretical Chemistry
Abstract
Phosphate is fundamental for optimal growth and reproduction for plants. However, due to low solubility, not all phosphorus in the soil is available to the plant. It has recently been discovered that plants can take up complex phosphate-containing organic compounds, such as phospholipids. This depends on membrane transporters, more specifically lipid flippases. In the model plant Arabidopsis, the lipid flippases ALA10 is upregulated by phosphate deficiency. ALA10 form together with ALA9, ALA11 and ALA12 an evolutionary subfamily, suggesting that they might be involved in similar cellular functions.

The aim was to design a strategy to obtain proof of concept that hyperactivation of specific flippases can lead to plants with an increased... (More)
Phosphate is fundamental for optimal growth and reproduction for plants. However, due to low solubility, not all phosphorus in the soil is available to the plant. It has recently been discovered that plants can take up complex phosphate-containing organic compounds, such as phospholipids. This depends on membrane transporters, more specifically lipid flippases. In the model plant Arabidopsis, the lipid flippases ALA10 is upregulated by phosphate deficiency. ALA10 form together with ALA9, ALA11 and ALA12 an evolutionary subfamily, suggesting that they might be involved in similar cellular functions.

The aim was to design a strategy to obtain proof of concept that hyperactivation of specific flippases can lead to plants with an increased phosphate utilization efficiency, using Arabidopsis as a model organism. This was done by creating yeast transformants containing C-terminal deletions of ALA10-ALA12 and a beta subunit. Lipid translocation was tested using flow cytometry. A small plant experiment was conducted to see if plants can grow under a phosphate deficiency.

It was found that the lipid uptake assay tested in this study was not enough to tell if ALA10-ALA12 with C-terminal deletions results in more lipid translocation and further investigation is needed. Preliminary results of ALA9 specificity suggest that it is a phosphatidylserine (PS) transporter. Results from a growth experiment suggest that Arabidopsis can grow under phosphate deficiency with a media containing lipids. (Less)
Popular Abstract
Phosphorus is a fundamental nutrient for plants without which plants cannot grow. However, phosphorus compounds tend to have low solubility which results in less available phosphorus for the plants in the soil. To compensate for this, millions of tons of phosphate-based fertilizers are used every year in the agricultural sector. These fertilizers are expensive, come from a limited resource and they are also responsible for a large proportion of freshwater pollution.

However, under conditions of phosphate limitation, the production of certain proteins, called flippases, is initiated, increasing the uptake efficiency of plant cells. These flippases transport complex phosphate-containing organic compounds, such as lipids, from the outside... (More)
Phosphorus is a fundamental nutrient for plants without which plants cannot grow. However, phosphorus compounds tend to have low solubility which results in less available phosphorus for the plants in the soil. To compensate for this, millions of tons of phosphate-based fertilizers are used every year in the agricultural sector. These fertilizers are expensive, come from a limited resource and they are also responsible for a large proportion of freshwater pollution.

However, under conditions of phosphate limitation, the production of certain proteins, called flippases, is initiated, increasing the uptake efficiency of plant cells. These flippases transport complex phosphate-containing organic compounds, such as lipids, from the outside to the inside of the plant cells. In the model plant Arabidopsis, the flippase ALA10 is responsible for taking up lipids through the root. Three other flippases (ALA9, ALA11 and ALA12) are 75 % similar to ALA10, suggesting that they might be involved in similar functions.

The hypothesis is that hyperactivation of ALA10 (and/or its related ALA proteins) will increase lipid uptake, mimicking conditions of phosphate deficiency and enhancing phosphate uptake, even under normal nutritional conditions. The aim is to design a strategy to obtain proof of this concept. This was done by first deleting the inhibitory end part of the flippase and then perform a lipid uptake assay. The amount of lipids taken up was compared between the mutated version of the flippase and the full length flippase. An experiment involving growing Arabidopsis wild type and a mutant lacking ALA10 and ALA11 was also performed to see if the plants can grow with lipids as a phosphate source.

The result shows that removing the end part of the flippase is not enough for the flippase to increase the uptake efficiency. Further experiments are needed to fully understand what happens when the end part of the flippase is removed and if the activity can be increased. The growth experiment suggests that plants can grow with a media containing lipids. This project will contribute to a better understanding of how plants can be engineered in order to improve phosphate utilization and remove the need for inorganic phosphate-based fertilizers, which are a big source of pollution of groundwater. (Less)
Please use this url to cite or link to this publication:
author
Jedemark, Louise LU
supervisor
organization
alternative title
Designa Superväxten: ökad lipidsignalering för förbättrad upptag av fosfor
course
KBKM05 20202
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Lipid flippases, Arabidopsis, Yeast, Transport biology, Applied Biochemistry, Tillämpad biokemi
language
English
id
9042613
date added to LUP
2021-04-01 10:44:08
date last changed
2021-04-01 10:44:08
@misc{9042613,
  abstract     = {Phosphate is fundamental for optimal growth and reproduction for plants. However, due to low solubility, not all phosphorus in the soil is available to the plant. It has recently been discovered that plants can take up complex phosphate-containing organic compounds, such as phospholipids. This depends on membrane transporters, more specifically lipid flippases. In the model plant Arabidopsis, the lipid flippases ALA10 is upregulated by phosphate deficiency. ALA10 form together with ALA9, ALA11 and ALA12 an evolutionary subfamily, suggesting that they might be involved in similar cellular functions. 

The aim was to design a strategy to obtain proof of concept that hyperactivation of specific flippases can lead to plants with an increased phosphate utilization efficiency, using Arabidopsis as a model organism. This was done by creating yeast transformants containing C-terminal deletions of ALA10-ALA12 and a beta subunit. Lipid translocation was tested using flow cytometry. A small plant experiment was conducted to see if plants can grow under a phosphate deficiency. 

It was found that the lipid uptake assay tested in this study was not enough to tell if ALA10-ALA12 with C-terminal deletions results in more lipid translocation and further investigation is needed. Preliminary results of ALA9 specificity suggest that it is a phosphatidylserine (PS) transporter. Results from a growth experiment suggest that Arabidopsis can grow under phosphate deficiency with a media containing lipids.},
  author       = {Jedemark, Louise},
  keyword      = {Lipid flippases,Arabidopsis,Yeast,Transport biology,Applied Biochemistry,Tillämpad biokemi},
  language     = {eng},
  note         = {Student Paper},
  title        = {Designing the Superplant: Increasing Lipid Signaling for Enhanced Phosphorus Uptake},
  year         = {2021},
}