The IncRNA, LRSC1 is a novel and unexpected regulator of plant responses to carbon dioxide?

Context Understanding the impact of global increases in atmospheric CO2 concentration [CO2] on crops is a key global research objective. Research over the last 10 years has revealed that, while there can be beneficial effects on yield, there are also trade-offs in terms of negative impacts on plant-water relations, nutrient uptake and leaf temperature. This is largely due to elevated [CO2]-induced reductions in stomatal aperture. These play out as reductions in evapotranspiration, which result in warmer leaves and reduced water and nutrient uptake from the soil. Accordingly, understanding the cellular mechanisms that allow stomata to respond to elevated [CO2] is vital for mitigating the negative effects of climate change on food production and nutrient content. Recently (unpublished) we have found that a long non-coding RNA (lncRNA) has a major role to play in the response of stomata and other cells in the leaf to increasing [CO2]. Our discovery is a completely novel and unexpected insight into plant CO2 responses and as such represents a potential step-change in our understanding. It opens up a totally new avenue of research investigation into the regulation of CO2 driven processes. The challenge LncRNAs are important regulators of gene expression in animals and plants. Unlike protein coding genes, lncRNAs do not usually encode for functional proteins. Instead, they regulate the expression of protein encoding genes. In Arabidopsis we have identified a lncRNA locus that we named Regulator of Stomatal CO2 sensitivity (LRSC1), whose transcripts are extremely highly enriched in guard cells compared with other leaf cell types and that has homologues in other members of the Brassicaceae. lrsc1 mutants consistently display significantly increased evapotranspiration, suggesting that the mutants’ guard cells are less sensitive to CO2. Remarkably, given the guard cell enrichment of the lncRNA transcripts, changes in whole leaf gene expression in response to increased [CO2] are also virtually eliminated in the mutant. Our challenge now is to understand the mechanism by which LRSC1 regulates plant responses to increasing [CO2]. Aim: To understand how LRSC1 regulates plant responses to CO2. To achieve this aim, we will address three objectives: 1) Determine the molecular mechanism of action of LRSC1. 2) Establish how LRSC1 regulates sensitivity to CO2. 3) Determine conserved functions of LRSC1 across the Brassicaceae. Potential applications and benefits In 2023, the UK Brassica and field vegetable market was worth £1.5 billion. Determining how LRSC1 regulates stomatal and leaf sensitivity to [CO2] will allow us to manipulate crop water use, nutrient, uptake and cooling in economically relevant Brassica species. More widely, we critically lack knowledge of cell-type specific responses to CO2. This project will identify CO2 responsive genes in different types of leaf cells, which may provide novel targets for engineering more productive crops that are resilient to increasing global CO2 levels. Relevance to BBSRC priorities Rising [CO2] and associated global warming is already having major impacts on crop productivity. Our research aligns with the BBSRC strategic delivery plan for sustainable agriculture and food and also addresses fundamental questions focused on understanding the rules of life.