Phenotyping of field-grown wheat in the UK highlights contribution of light response of photosynthesis and flag leaf longevity to grain yield

Quantification of Photosynthetic Enzymes in Leaf Extracts by Immunoblotting

In this chapter, we describe a method to extract and quantify photosynthetic enzymes using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The method is particularly suitable for characterizing altered protein amounts in leaves of plants produced from genetic engineering or gene-editing approaches. We focus on RuBisCO and RuBisCO activase, a molecular chaperone required to sustain the activity of RuBisCO and CO₂ fixation, yet the method can be easily adapted to investigate other leaf proteins of interest.

Extraction of RuBisCO to Determine Catalytic Constants

RuBisCO enables net carbon fixation through the carboxylation of RuBP during photosynthesis. Its complex biochemistry and catalytic diversity found among different plants make characterization of RuBisCO properties useful for investigations aimed at improving photosynthetic performance. This chapter reports methods for rapid extraction of soluble proteins to examine RuBisCO catalytic properties, and for large-scale purification of RuBisCO from leaves to measure the specificity of the enzyme toward its gaseous substrates.

Contrasting Root and Photosynthesis Traits in a Large-Acreage Canadian Durum Variety and Its Distant Parent of Algerian Origin for Assembling Drought/Heat Tolerance Attributes

In Canada, the world's top exporter of high-protein durum, varietal development over its nearly six-decade history has been driven by a quest for yield improvement without compromise on grain protein content and other quality aspects. Pelissier, a landrace selection from Algeria that was introduced into North America more than a century ago and the variety Strongfield that was released in 2004 are notable. Pelissier, known to elaborate more roots and considered as drought tolerant, has been cultivated commercially and thus deemed adapted. Strongfield has Pelissier in its pedigree, and it remains a high-acreage variety. Strongfield was found to elaborate only about half of the root biomass of Pelissier at maturity in greenhouse trials under well-watered conditions. Extended drought stress caused a significant reduction in the root biomass of both lines. However, Pelissier under drought maintained at least as much root biomass as that of Strongfield under well-watered conditions. In comparison to Pelissier, it had a superior photosynthesis rate (27.16 μmol CO2 m-2 s-1), capacity for carboxylation (Vcmax: 132.83 μmol CO2 m-2 s-1) and electron transport/ribulose-1,5-bisphosphate (RuBP) regeneration (Jmax: 265.40 μmol CO2 m-2 s-1); the corresponding values for Pelissier were 19.62 μmol CO2 m-2 s-1, 91.87 μmol CO2 m-2 s-1, and 163.83 μmol CO2 m-2 s-1, respectively, under well-watered conditions. Under short-term/mild drought conditions, the carbon assimilation rate remained stable in Pelissier while it declined in Strongfield to the Pelissier level. However, Strongfield succumbed to extended drought sooner than Pelissier. Photosynthesis in Strongfield but not Pelissier was found to be sensitive to high temperature stress. These results provide encouraging prospects for further exploitation of beneficial physiological traits from Pelissier in constructing climate-resilient, agronomically favorable wheat ideotypes.

Leaf Photosynthetic Parameters Related to Biomass Accumulation in a Global Rice Diversity Survey

Mining natural variations is a major approach to identify new options to improve crop light use efficiency. So far, successes in identifying photosynthetic parameters positively related to crop biomass accumulation through this approach are scarce, possibly due to the earlier emphasis on properties related to leaf instead of canopy photosynthetic efficiency. This study aims to uncover rice (Oryza sativa) natural variations to identify leaf physiological parameters that are highly correlated with biomass accumulation, a surrogate of canopy photosynthesis. To do this, we systematically investigated 14 photosynthetic parameters and four morphological traits in a rice population, which consists of 204 U.S. Department of Agriculture-curated minicore accessions collected globally and 11 elite Chinese rice cultivars in both Beijing and Shanghai. To identify key components responsible for the variance of biomass accumulation, we applied a stepwise feature-selection approach based on linear regression models. Although there are large variations in photosynthetic parameters measured in different environments, we observed that photosynthetic rate under low light (Alow) was highly related to biomass accumulation and also exhibited high genomic inheritability in both environments, suggesting its great potential to be used as a target for future rice breeding programs. Large variations in Alow among modern rice cultivars further suggest the great potential of using this parameter in contemporary rice breeding for the improvement of biomass and, hence, yield potential.