Measuring the dynamic photosynthome

Abstract

BackgroundPhotosynthesis underpins plant productivity and yet is notoriously sensitive to small changes in environmental conditions, meaning that quantitation in nature across different time scales is not straightforward. The ‘dynamic’ changes in photosynthesis (i.e. the kinetics of the various reactions of photosynthesis in response to environmental shifts) are now known to be important in driving crop yield.ScopeIt is known that photosynthesis does not respond in a timely manner, and even a small temporal ‘mismatch’ between a change in the environment and the appropriate response of photosynthesis toward optimality can result in a fall in productivity. Yet the most commonly measured parameters are still made at steady state or a temporary steady state (including those for crop breeding purposes), meaning that new photosynthetic traits remain undiscovered.ConclusionsThere is a great need to understand photosynthesis dynamics from a mechanistic and biological viewpoint especially when applied to the field of ‘phenomics’ which typically uses large genetically diverse populations of plants. Despite huge advances in measurement technology in recent years, it is still unclear whether we possess the capability of capturing and describing the physiologically relevant dynamic features of field photosynthesis in sufficient detail. Such traits are highly complex, hence we dub this the ‘photosynthome’. This review sets out the state of play and describes some approaches that could be made to address this challenge with reference to the relevant biological processes involved.

Dynamic non‐photochemical quenching in plants: from molecular mechanism to productivity

“…To understand the reasons underlying this surprising assertion one also has to appreciate the processes and the rationale that underlies the regulation of leaf photosynthesis, partly covered in the NPQ mechanism described above. Central to this, is the coordination of ATP and NADPH formation with the metabolic activity of the Calvin cycle and the limitation of the production of ROS (Kaiser et al , ; Murchie et al , ). For this to occur, the energy supply to the ETC (from PSII and PSI) must be proportional to the capacity for its use.…”

“…The events just described can occur on a second‐by‐second basis. By comparison, a leaf held for several minutes in the same conditions will often demonstrate a statistically unchanging rate of gas exchange, NPQ and electron transport, the so‐called ‘steady state’ (Murchie et al , ). It has been suggested that this represents optimal photosynthesis whereas a change in rate represents a suboptimal rate (Kaiser et al , ).…”

Converging phenomics and genomics to study natural variation in plant photosynthetic efficiency

“…In this section, various aspects of photosynthesis are discussed which require future attention in genetic mapping studies, but which impose serious challenges to phenotyping strategies. Photosynthetic responses due to environmental change are among those where most genetic variation is expected and novel traits are to be discovered (Lawson et al, ), but which are simultaneously the most difficult to properly track (Murchie et al ., ; Rungrat et al ., ).…”

“…The identification of functional allelic variations of important genes and traits related to photosynthesis using a forward genetics analysis of diversity panels is therefore a valuable approach, for three main reasons. First, the study of natural variation offers key insights into regulatory processes of photosynthesis, for example under fluctuating light conditions (Lawson et al ., ; Murchie et al ., ). Furthermore, genetic variation in the core genes of photosynthesis has been acknowledged to be an important resource for the bio‐engineering of improved photosynthesis (Prins et al ., ; Reeves et al ., ).…”

“…Despite the potential for increasing photosynthetic efficiency, major bottlenecks in the phenotypic and genotypic evaluation of photosynthesis‐related traits exist (Flood et al ., ; Murchie et al ., ). In the last 10 years, however, both plant genomics and phenomics have matured to the point where, together, they can be used in forward genetics analyses of photosynthetic traits.…”