Natural variation in photosynthetic capacity, growth, and yield in 64 field-grown wheat genotypes.

S M Driever,C A Raines,M A J Parry,P J Andralojc,T Lawson

doi:10.1093/jxb/eru253

S M Driever, C A Raines + Show 3 more

Open Access

https://doi.org/10.1093/jxb/eru253

Copy DOI

Abstract

Increasing photosynthesis in wheat has been identified as an approach to enhance crop yield, with manipulation of key genes involved in electron transport and the Calvin cycle as one avenue currently being explored. However, natural variation in photosynthetic capacity is a currently unexploited genetic resource for potential crop improvement. Using gas-exchange analysis and protein analysis, the existing natural variation in photosynthetic capacity in a diverse panel of 64 elite wheat cultivars grown in the field was examined relative to growth traits, including biomass and harvest index. Significant variations in photosynthetic capacity, biomass, and yield were observed, although no consistent correlation was found between photosynthetic capacity of the flag leaf and grain yield when all cultivars were compared. The majority of the variation in photosynthesis could be explained by components related to maximum capacity and operational rates of CO2 assimilation, and to CO2 diffusion. Cluster analysis revealed that cultivars may have been bred unintentionally for desirable traits at the expense of photosynthetic capacity. These findings suggest that there is significant underutilized photosynthetic capacity among existing wheat varieties. Our observations are discussed in the context of exploiting existing natural variation in physiological processes for the improvement of photosynthesis in wheat.

Highlights

Wheat is one of the most important crops, providing over 20% of the calories consumed by the world’s population and a similar proportion of protein for about 2.5 billion people (Braun et al, 2010)
The products of photosynthesis are the primary determinants of plant productivity, and increasing photosynthesis has been widely recognized as a key trait to increase yields (Long et al, 2006; Zhu et al, 2010; Parry et al, 2011; Raines, 2011)
While biomass is a function of the total photosynthesis of the canopy over time, the flag leaves have, in the UK, been identified as the major contributor to grain yield (Thorne, 1973)

Summary

Introduction

Wheat is one of the most important crops, providing over 20% of the calories consumed by the world’s population and a similar proportion of protein for about 2.5 billion people (Braun et al, 2010). Current increases in global wheat productivity are only 1.1% per annum (Dixon et al, 2009) or even static in some regions (Brisson et al, 2010), while the predicted global demand is likely to increase by 1.7% per annum until 2050 (Rosegrant and Agcaoili, 2010). It is clear that the current yield gain per annum in wheat is insufficient to meet the growing demand, and that new approaches to increasing productivity are essential to avoid shortfalls of growing severity (Hawkesford et al, 2013). In the absence of chronic environmental stress, Abbreviations: A, CO2 assimilation; ANOVA, analysis of variance; CABP, 2′-carboxyarabinitol-1, 5-bisphosphate; Ci, intercellular CO2 concentration; Ci, intercellular CO2 concentration; ERYCC, Earliness & Resilience for Yield in a Changed Climate; gm, mesophyll conductance; h2, heritability; Jmax, maximum rate of electron transport demand for RuBP regeneration; PC, principle component; PCA, principle components analysis; PEG, polyethylene glycol; PPFD, photosynthetic photon flux density; Rd, respiration rate; Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase; RuBP, ribulose-1,5-bisphosphate; SBPase, sedoheptulose-1,7-biphospatase; Vcmax, maximum velocity of Rubisco for carboxylation

Objectives

Methods

Results

Conclusion