Phenotypic variation in photosynthetic traits in wheat grown under field versus glasshouse conditions

Recognition of the untapped potential of photosynthesis to improve crop yields has spurred research to identify targets for breeding. The CO2-fixing enzyme Rubisco is characterized by a number of inefficiencies, and frequently limits carbon assimilation at the top of the canopy, representing a clear target for wheat improvement. Two bread wheat lines with similar genetic backgrounds and contrasting in vivo maximum carboxylation activity of Rubisco per unit leaf nitrogen (V-c,V-max,V-25/N-area) determined using high-throughput phenotyping methods were selected for detailed study from a panel of 80 spring wheat lines. Detailed phenotyping of photosynthetic traits in the two lines using glasshouse-grown plants showed no difference in V-c,V-max,V-25/N-area determined directly via in vivo and in vitro methods. Detailed phenotyping of glasshouse-grown plants of the 80 wheat lines also showed no correlation between photosynthetic traits measured via high-throughput phenotyping of field-grown plants. Our findings suggest that the complex interplay between traits determining crop productivity and the dynamic environments experienced by field-grown plants needs to be considered in designing strategies for effective wheat crop yield improvement when breeding for particular environments. Wheat plants grown in the glasshouse show different physiological properties compared with plants grown under dynamic field conditions, highlighting the need to consider realistic environmental conditions when breeding for particular environments.

Automated summary

Research on the potential of photosynthesis to improve crop yields has led to the identification of breeding targets. The enzyme Rubisco, responsible for CO2 fixation, is inefficient and often limits carbon assimilation in wheat. Two bread wheat lines with similar genetic backgrounds but contrasting Rubisco activity were chosen for detailed study. Phenotypic analysis of photosynthetic traits in these lines showed no difference in Rubisco activity between in vivo and in vitro methods. Additionally, there was no correlation between photosynthetic traits measured in field-grown plants using high-throughput phenotyping. These findings highlight the need to consider the complex interplay between traits and the dynamic environment in breeding strategies for wheat yield improvement.