Rice (Oryza sativa L.) contributes to the diets of around 3.5 billion people every day and is consumed more than any other plant. Alarmingly, climate predictions suggest that the frequency of severe drought and high-temperature events will increase, and this is set to threaten the global rice supply. In this review, we consider whether water or heat stresses in cropsespecially ricecould be mitigated through alterations to stomata; minute pores on the plant epidermis that permit carbon acquisition and regulate water loss. In the short-term, water loss is controlled via alterations to the degree of stomatal "openness", or, in the longer-term, by altering the number (or density) of stomata that form. A range of molecular components contribute to the regulation of stomatal density, including transcription factors, plasma membrane-associated proteins and intercellular and extracellular signaling molecules. Much of our existing knowledge relating to stomatal development comes from research conducted on the model plant, Arabidopsis thaliana. However, due to the importance of cereal crops to global food supply, studies on grass stomata have expanded in recent years, with molecular-level discoveries underscoring several divergent developmental and morphological features. Cultivation of rice is particularly water-intensive, and there is interest in developing varieties that require less water yet still maintain grain yields. This could be achieved by manipulating stomatal development; a crop with fewer stomata might be more conservative in its water use and therefore more capable of surviving periods of water stress. However, decreasing stomatal density might restrict the rate of CO 2 uptake and reduce the extent of evaporative cooling, potentially leading to detrimental effects on yields. Thus, the extent to which crop yields in the future climate will be affected by increasing or decreasing stomatal density should be determined. Here, our current understanding of the regulation of stomatal development is summarised, focusing particularly on the genetic mechanisms that have recently been described for rice and other grasses. Application of this knowledge toward the creation of "climate-ready" rice is discussed, with attention drawn to the lesser-studied molecular elements whose contributions to the complexity of grass stomatal development must be understood to advance efforts.
Sugars are essential metabolites for energy and anabolism that can also act as signals to regulate plant physiology and development. Experimental tools to disrupt major sugar signalling pathways are limited. We performed a chemical screen for modifiers of activation of circadian gene expression by sugars to discover pharmacological tools to investigate and manipulate plant sugar signalling.Using a library of commercially available bioactive compounds, we identified 75 confident hits that modified the response of a circadian luciferase reporter to sucrose in dark-adapted Arabidopsis thaliana seedlings. We validated the transcriptional effect on a subset of the hits and measured their effects on a range of sugar-dependent phenotypes for 13 of these chemicals. Chemicals were identified that appear to influence known and unknown sugar signalling pathways.Pentamidine isethionate was identified as a modifier of a sugar-activated Ca 2+ signal that acts as a calmodulin inhibitor downstream of superoxide in a metabolic signalling pathway affecting circadian rhythms, primary metabolism and plant growth.Our data provide a resource of new experimental tools to manipulate plant sugar signalling and identify novel components of these pathways.
Sugars are the major product of photosynthesis and provide the stored energy and basic building blocks for all living cells. Sugars also act as dynamic signals throughout the plant life cycle to regulate growth, development and interactions with the biotic and abiotic environment. From a previous RNA-seq experiment, we have identified eight sugar-regulated WRKY transcription factor genes. Focusing on four, we find that WRKY11, WRKY17, WRKY60 and WRKY72 are upregulated by sucrose, glucose or fructose by a superoxide signalling pathway. WRKY gene expression is downregulated by 2-deoxyglucose (2-DG) or mannose, which are inhibitors of hexokinase (HXK), and in hxk1-3 mutants. Mutants in WRKY17, WRKY60 or WRKY72 have reduced hypocotyl growth in response to sucrose, but do not have altered circadian period. Our data suggest that HXK1-dependent regulation of WRKY genes by sugars represents a superoxide-activated transcriptional subnetwork that influences plant growth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.