By Juan Alejandro Perdomo, Lancaster Photosynthesis group postdoc.

“The relative abundance of wheat Rubisco activase isoforms is post-transcriptionally regulated.”
Perdomo, Buchner & Carmo-Silva, Photosynthesis Research (Paper link.)

Rubisco, the most abundant enzyme in plants, and its chaperone Rubisco activase (Rca) are key enzymes for photosynthesis. We wanted to get a better understanding of how much the expression and amount of these photosynthetic proteins vary during the day.

To obtain data over a suitable timescale to show how Rubisco and Rca varies in accordance with the daily cycle, and I slept outside the growth chambers for two days. We’ve learnt a number of interesting things from these results.

We found that alongside the different regulatory properties of each of the three Rca isoforms in wheat, each of them also shows different daily patterns. TaRca1-β expression was almost null during the whole daily cycle. The redox-sensitive TaRca-α isoform was less abundant, representing 85% of the redox-insensitive TaRca2-β at the transcript level and 12.5% at the protein level. Therefore, our results show that in wheat plants TaRca2-β is the isoform with the highest expression and amount. These changes in Rca isoform abundance and ratio are imperative since the three wheat Rca isoforms activate Rubisco at different rates and differ in their sensitivity to temperature and changes in the ADP/ATP ratio.

We found that Rubisco amounts are pretty constant during the daytime. However, its abundance dropped by 20% by the middle of the night. Could this be due to a high Rubisco degradation during the night, which represents a big nitrogen sink for wheat plants? We don’t yet know, but our data is an interesting note to explore further in the future.

On the other hand, gene expression and protein amount did not correlate for Rubisco or any of the Rca isoforms during the daily cycle. This outcome suggests that the abundance of both enzymes and their isoforms is post-transcriptionally regulated, and that for these proteins transcript levels are insufficient to predict functional protein levels. Though we have seen evidence of temperature impacts on transcription and subsequent protein amounts for the more thermally stable TaRca1-β isoform.

This was an interesting experiment to do to better understand how the expression of the different isoforms of this key regulator of photosynthesis behaves during the day (even if it meant some long nights sampling!). As we gain more and more understanding of both the expression and biochemical variability of wheat Rubisco activase isoforms, it gives us further knowledge to apply to improving the efficiency of photosynthesis, and improving wheat production for more sustainable, secure food production.

Tomorrow Tuesday 18th May is 2021 Fascination of Plants Day!

Members of the team have prepared a range of activities, tips, quizzes and even recipes that link to our Lancaster Photosynthesis!

You can check out the details here and the team will be tweeting tomorrow to share!

As part of her UKRI Future Leaders work on C2 Photosynthesis, there are currently 3 opportunities to join her in this exciting area!

Links to the positions for further details, and to access to application portal, can be found via our twitter here.

As part of her recently funded UKRI FLF work on engineering C2 photosynthesis, there is an exciting opportunity to work with Marj for a 42 month Senior Postdoctoral Associate role, with the potential for this to be extended.

You can find more about the work here.  Or on her LEC page here.

Application details and further details are available via the Lancaster University jobs page portal.
*Please note that full instructions are at the above link, all applications must be submitted through the portal.

Well done to Alejandro, Peter, and Elizabete whose work on expression and translation of the different wheat Rubisco Activase isoforms has just been published in Photosynthesis Research.

You can check out the paper here: tinyurl.com/3cv9pu8h

Congratulations to Alex Sokolnik who successfully complete his MRes viva this week! Well done!

Alex was working on cowpea development, and like many had to adapt and dramatically change his (formerly lab-based) project part way through.

Really valuable publication recently out from a large group of people including Lancasters Sam Taylor and Marj Lundgren.

This new paper “A reporting format for leaf-level gas exchange data and metadata” is just that, a set of advice and conventions for reporting your gas exchange.
This will help the community more easily share data on repositories and facilitate more detailed and larger meta-analyses, making everyones data and work even more valuable.

Check it out at Ecological Informatics

Congratulations are in order for team member Louis Caruana, who last week passed his MRes viva.
Well done Louis!
Louis’ did a great job having to adjust to an silico project like may others in the changing circumstances, and has produced some very nice work on Rubisco, Rca and related genes.

Thanks also to the internal and external examiners for an interesting and constructive conversation with Louis, with great feedback.

Louis is continuing with the team, now working on an ongoing project with wheat.

Well done to group members Louis Caruana and Alex Sokolnik who both recently submitted their Masters by Research theses, and are now preparing for their vivas.

Great job on all your hard work on this in challenging times!

A massive congrats to our resident C2 expert PI Marjorie Lundgren!

She has been awarded a UKRI Future Leaders Fellowship to continue her exciting work on C2 here at Lancaster!

You can see the news item from Lancaster here, and check out a recent review by Marj.