A new model for chloroplast-to-nucleus communication during seedling development
Lead Research Organisation:
University of Cambridge
Department Name: Plant Sciences
Abstract
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Technical Summary
The development of photosynthetically-active chloroplasts is a critical phase during seedling development and requires co-ordination between the nucleus and chloroplasts. Chloroplasts are able to signal the nucleus to regulate gene expression, but this pathway is poorly understood and represents a major gap in our knowledge. In this proposal we have developed a new model for chloroplast-to-nucleus communication that is consistent with published data in the field and comprises both a promotive pathway from developing chloroplasts mediated by a specific heme pool, and an inhibitory pathway when changes in environmental conditions leads to the accumulation of photo-toxic chlorophyll intermediates. We will test this model robustly in three ways. Firstly we will manipulate heme levels by overexpression of the heme biosynthesis enzyme ferrochelatase and the heme-degrading enzyme heme oxygenase and follow the effect of this on nuclear gene expression. We will also develop new methodology to measure heme pools accurately within seedlings subjected to treatments affecting chloroplast signaling. Secondly, we will determine whether the chloroplast protein GUN1 functions as a repressor of chloroplast development, as we hypothesize, rather than as a central integrator of various chloroplast signaling pathways as generally proposed. We will do this by examining chloroplast development in new gun1 mutants and a GUN1 overexpressor, and testing whether GUN1 affects accumulation of the specific heme pool that functions as the promotive signal. Thirdly, we will identify components of the inhibitory pathway by undertaking a molecular characterization of five mutants unable to downregulate nuclear gene expression following accumulation of chlorophyll intermediates in the light. These mutants have already been isolated and represent a significant resource to this project.
Planned Impact
Plants are central both to agriculture, and to conservation of the natural environment. As well as food, they offer resources for construction, natural fibre, and fuel, and contribute to mitigation of climate change. Given these key roles, it is becoming increasingly recognised that we need to understand better the factors that ensure plant productivity so that we can safeguard our food and, increasingly, fuel supply. The most vulnerable stage of a plant's life is during seedling establishment as it becomes photosynthetically competent. This project will study how the photosynthetic apparatus is assembled efficiently and safely in the early stages of seedling development, and how this may be affected by environmental conditions. Our research will have academic impact, and will provide indicators that may be useful in crop plant management and chloroplast biotechnology.
For the academic community, the topic of chloroplast-to-nucleus signaling has been the subject of considerable research effort, but is still poorly understood. As well as researchers in chloroplast biogenesis, a better understanding of how chloroplasts communicate will also benefit those in the related fields of photosynthesis, photomorphogenesis and stress signaling. The methodology that we will develop during the project to measure heme and other tetrapyrroles will be applicable to many analytical projects both academically and in the medical/industrial arenas. The technician employed on the grant will become highly skilled in the use of sophisticated analytical equipment and methodology, enabling her to progress further in a scientific career. The PDRA will benefit from the opportunity to collaborate with and visit Professor Terauchi at Iwate Biotechnology Research Center in Japan.
In terms of the economic impact, our work on chloroplast development in seedlings will impact on our understanding of seedling establishment, an essential factor in plant survival and therefore crop productivity. Moreover, information about how chloroplasts interact with the environment to provide information to the cell is of considerable interest and likely to be important in designing crop plants that will be able to withstand future environmental change scenarios. Future industrial biotechnological approaches using plants will increasingly focus on strategies to harness the biosynthetic potential of chloroplasts, so a better understanding of the interactions of these organelles with the rest of the cell will support these endeavours. To ensure information from this project has significant impact in these commercial sectors we will continue with links that have been developed with technology transfer enterprises and networks, as well as commercial partners, to exploit opportunities arising from this work. Both applicants (independently) are engaged in more targeted research related to the development of algal biofuels and information and skills arising from the current proposal will be beneficial in supporting this work
Both applicants will utilize ongoing and new public outreach activities to explain the role of light and photosynthesis in plant biology through both school activities and to the general public. The current project has important implications for all those interested in plant productivity whether for agriculture, forestry, conservation, bioenergy or the use of plants for the expression of high value products. The work in the current study will also utilise the model plant Arabidopsis to address a fundamental cellular process, namely communication between organelles. Basic research undertaken with Arabidopsis has been shown to translate not only into crop plants but more broadly to be better understanding of fundamental cellular processes that can impact on human health (Jones et al, 2008, Cell 133, 939-43). These are important broad messages about the potential impact of this work that we intend to communicate.
For the academic community, the topic of chloroplast-to-nucleus signaling has been the subject of considerable research effort, but is still poorly understood. As well as researchers in chloroplast biogenesis, a better understanding of how chloroplasts communicate will also benefit those in the related fields of photosynthesis, photomorphogenesis and stress signaling. The methodology that we will develop during the project to measure heme and other tetrapyrroles will be applicable to many analytical projects both academically and in the medical/industrial arenas. The technician employed on the grant will become highly skilled in the use of sophisticated analytical equipment and methodology, enabling her to progress further in a scientific career. The PDRA will benefit from the opportunity to collaborate with and visit Professor Terauchi at Iwate Biotechnology Research Center in Japan.
In terms of the economic impact, our work on chloroplast development in seedlings will impact on our understanding of seedling establishment, an essential factor in plant survival and therefore crop productivity. Moreover, information about how chloroplasts interact with the environment to provide information to the cell is of considerable interest and likely to be important in designing crop plants that will be able to withstand future environmental change scenarios. Future industrial biotechnological approaches using plants will increasingly focus on strategies to harness the biosynthetic potential of chloroplasts, so a better understanding of the interactions of these organelles with the rest of the cell will support these endeavours. To ensure information from this project has significant impact in these commercial sectors we will continue with links that have been developed with technology transfer enterprises and networks, as well as commercial partners, to exploit opportunities arising from this work. Both applicants (independently) are engaged in more targeted research related to the development of algal biofuels and information and skills arising from the current proposal will be beneficial in supporting this work
Both applicants will utilize ongoing and new public outreach activities to explain the role of light and photosynthesis in plant biology through both school activities and to the general public. The current project has important implications for all those interested in plant productivity whether for agriculture, forestry, conservation, bioenergy or the use of plants for the expression of high value products. The work in the current study will also utilise the model plant Arabidopsis to address a fundamental cellular process, namely communication between organelles. Basic research undertaken with Arabidopsis has been shown to translate not only into crop plants but more broadly to be better understanding of fundamental cellular processes that can impact on human health (Jones et al, 2008, Cell 133, 939-43). These are important broad messages about the potential impact of this work that we intend to communicate.
Organisations
People |
ORCID iD |
Alison Smith (Principal Investigator) |
Publications
Page MT
(2017)
Seedlings Lacking the PTM Protein Do Not Show a genomes uncoupled (gun) Mutant Phenotype.
in Plant physiology
Page MT
(2017)
Singlet oxygen initiates a plastid signal controlling photosynthetic gene expression.
in The New phytologist
Page MT
(2020)
Overexpression of chloroplast-targeted ferrochelatase 1 results in a genomes uncoupled chloroplast-to-nucleus retrograde signalling phenotype.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Rovira A
(2019)
PPR proteins - orchestrators of organelle RNA metabolism.
Rovira A
(2019)
PPR proteins - orchestrators of organelle RNA metabolism
in Physiologia Plantarum
Description | - Heme and chlorophyll are made in plant and algal cells via a common pathway. As well as being an important compound for normal functioning of cells (functional heme), heme is used as a signal from the chloroplast - where photosynthesis takes place - to signal to the nucleus, which is where the genes for most chloroplast proteins are located. This is called regulatory heme. - Our partners at the University of Southampton are producing plant lines that have altered levels of enzymes involved in heme synthesis and breakdown to see what happens to expression of the nuclear genes for chloroplast proteins. - We have optimised several methods that allow measurement of heme in plant material whilst minimising interference from chlorophyll. However they are not sensitive enough to measure the small pool of regulatory heme against the very large amounts of functional heme. - We have optimised the process for measurement of intermediates of heme and chlorophyll synthesis so that we can study the effect of the mutant lines from Southampton. It is possible to estimate the role of regulatory heme by this approach. - We have initiated a collaboration with colleagues at University of California Davis to study similar process in a green alga |
Exploitation Route | Understanding chloroplast development is important for approaches to increase plant productivity. |
Sectors | Agriculture Food and Drink Energy Environment |
Description | SRA Payam Mehrshahi and Dr Lorraine Archer presented via a video walk-through the Algal Innovation Centre for the EIT food workshop ALGAL BIOTECHNOLOGY 2020 - TECHNIQUES AND OPPORTUNITIES FOR THE SUSTAINABLE BIOECONOMY |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | Due to Covid-19 restrictions the EIT Food Professional Development course was redesigned so that 3x 2day courses were combined and presented online once over a two-day course. As the lead organisation, the University of Cambridge team (Payam Mehrshahi, Matthew Davey, Lorraine Archer) produced daily programme of lecture/seminars that brought together leading international experts to introduce the theory of techniques, SOPs best practice and live demonstration of equipment and facilities. The course offered insights and examples from an industrial and entrepreneurial perspective, that helped the participants to start or improve their own algal-based business. The video walk-through of the Algal Innovation Centre at the University of Cambridge was designed by Payam and Lorraine to reflect the wide range of research involving algae that is carried out in the university and in this facility. The 30 minute video was followed by a 45 minute Q&A session during which participants asked about technical aspects of equipment, consumables, algae strains, culturing conditions and trouble shooting advice. |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.eitfood.eu/media/documents/ALGAL_BIOTECH_DRAFT_TRAINING_COURSE_2020_FINAL_v10.pdf |
Description | SRA Payam Mehrshahi presented at the EIT food workshop ALGAL BIOTECHNOLOGY 2020 - TECHNIQUES AND OPPORTUNITIES FOR THE SUSTAINABLE BIOECONOMY |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | In 2020 due to the COVID restrictions, the EIT Food professional development course ALGAL BIOTECHNOLOGY - TECHNIQUES AND OPPORTUNITIES FOR THE SUSTAINABLE BIOECONOMY was held as a hybrid course. This course was developed and led by colleagues at The University of Cambridge (UK), Matis (Iceland) and Fraunhofer (Germany). The course attendees were graduate, postgraduate and industry professionals who are interested in gaining exposure to the latest insight into technical, commercial and policy concepts that impact algal biotechnology. Payam's talk titled "Genetic Engineering Approaches For Algal Biotechnology" was followed by a Q&A session. The range of questions was testament to the diversity of interests and stage in career of those in attendance. |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.eitfood.eu/projects/algal-biotechnology-techniques-and-opportunities-for-the-sustainable... |