Monitoring Photosynthesis by In Vivo Chlorophyll Fluorescence: Application to High-Throughput Plant Phenotyping

Abstract

In spite of the decrease in the rate of population growth, world population is expected to rise from the current figure (slightly above to 7.2 billion) to reach 9.6 billion in 2050. There is therefore a pressing need to increase food production. Since most of the best arable lands are already under production, expanding the agricultural areas would have negative impacts on important natural areas. Thereby, increasing the productivity of the current agricultural areas is the chief objective of agronomical planners, and planting more productive and better adapted plant varieties is crucial to achieve it. In fact, plant breeding is at the forefront of concern of both agronomists and plant biologists. Plant breeding is a millenary activity that deeply changed our world. However, the use of molecular biology techniques jointly with informatics capabilities-giving rise to the omics techniquesdeeply accelerated plant breeding, providing new and better plant varieties at an increased pace. The advances in genomics, though, far by-passed the advances in phenomics, and so there is a rising consensus among plant breeders that plant phenotyping is a bottleneck to advancing plant breeding. Therefore, a range of international initiatives in highthroughput plant phenotyping (HTPP) are at course, and new automated equipment is being developed. Phenotyping plants, however, is not a simple matter. To begin with, it has to be decided which parameters to measure in order to extrapolate to the desired goals, plant resistance and plant productivity. For this, as well as for plant breeding, an indepth knowledge of plant physiology is required. Photosynthesis has been considered as a good indicator of overall plant performance. It is the only energy input in plants and thereby impacts all aspects of plant metabolism and physiology. The cumulative rate of photosynthesis over the growing season is the primary determinant of crop biomass. It largely determines the redox state of plant cells, and therefore, it is at the core of regulatory networks. Therefore, assessing photosynthesis and the photosynthetic apparatus plays a core role on plant phenotyping. Nevertheless, high-throughput phenotyping demands very rapid measurements, and consequently the most common method of photosynthesis measurement-the infra-red gas analysis-is not well suited for this purpose. On the contrary, the techniques based on in vivo chlorophyll (Chl) a fluorescence measurements are perfectly fit. In this chapter, an historical perspective on the development of in vivo Chl a measurement is briefly addressed. Then, the state of the art of the fluorescence-based techniques of photosynthesis assessment is presented, and their potential use in HTPP is evaluated. Finally, the current use of these techniques in the main systems of phenotyping is surveyed.

Robust Microplate-Based Methods for Culturing and in Vivo Phenotypic Screening of Chlamydomonas reinhardtii

“…The photopigments, chlorophylls and carotenoids, provide valuable insight into photosynthetic potential, metabolic flux, and cell stress ( Lichtenthaler and Rinderle, 1988 ; Boyle and Morgan, 2009 ; da Silva, 2016 ). Our plate based assay has the potential to measure relative photopigment concentrations in a non-destructive in vivo manner.…”

“…Quantifying photopigments is traditionally a terminal process, whereby samples are extracted in solvents and measured spectrophotometrically ( Lichtenthaler, 1987 ). However, photopigments such as carotenoids are especially good indicators of cell stress and a microplate method to analyze this in a non-destructive fashion would be especially useful ( Peñuelas et al, 1993 ; Lobato et al, 2010 ; Havaux, 2014 ; da Silva, 2016 ). Here we have established a method to determine both chlorophyll as well as carotenoid concentrations directly through absorbance measurements based on corrections due to the bathochromic (red) shift and an extraction normalization.…”

Using Chlorophyll a Fluorescence Imaging to Select Desiccation-Tolerant Native Moss Species for Water-Sustainable Green Roofs

“…The introduction of imaging technologies, such as the long-established chlorophyll a fluorescence measurement [25], a non-invasive technique that allows obtaining topographic representations of photosynthesis over a biological surface, allows the screening for organisms/samples with varied photosynthetic performances [26]. The recent development of the lower-cost user-made systems [27] facilitates the use of this technique for screening bryophytes most suitable for green roof technologies.…”

“…The introduction of imaging technologies to the in vivo chlorophyll a fluorescence measurement allowed to obtain spatial (topographic) representations of photosynthetic activity over a biological surface. Furthermore, this combined approach is an effective method, fostering for screening organisms/samples with different photosynthetic performance, as well as providing a lower-cost and faster tool for establishing user-made systems [26,27].…”

Effect of tobacco smoke on the growth, biochemical composition, and biodiesel characteristics of two Chlamydomonas strains

“…Monitoring photosynthetic pigments such as chlorophyll and carotenoids offers a valuable understanding of cell stress, metabolic ux, and photosynthetic potential [31]. Changes induced by various stressors are initially detectable in photosynthetic pigments changes before the recognition of any changes in the growth [32].…”