The technologies behind high-throughput phenotyping are transforming ecophysiology, but the generation of new knowledge about how plants function is limited by the lack of a conceptual framework. Functional phenomics delivers a next-generation plant physiology framework using phenotyping, physiology, multivariate statistics, and simulation modeling to generate and test new hypotheses about how plant traits integrate to influence plant performance. The trait economics spectrum is a conceptual framework from ecology that could be useful for exploring whole plant trait integration in crops. In this context, economics refers to the balance among traits for resource acquisition and utilization, with explicit treatment of the tradeoffs between pairs of traits. A root economics spectrum has been proposed in which root respiration correlates to percent nitrogen, root length per mass, and the decomposition rate of dried roots in soil. To investigate the root economics spectrum, 276 diverse wheat (Triticum aestivum) genotypes with available sequence data were intensively phenotyped for a suite of shoot and root traits including specific root length and specific root respiration using open source tools such as RhizoVision Analyzer. Substantial intraspecific genetic variation was discovered for all traits measured. Nearly 5-fold variation was found among the wheat lines for specific root respiration on a root length basis, with a heritability of 0.46. Specific root length was found to have even greater heritability than shoot mass (0.6 and 0.57, respectively). Correlation networks among root economics traits confirm expectations based on previous literature. Genome-wide association studies (GWAS) for the univariate traits uncovered several genetic regions associated with variation in these economics traits. Excitingly, multivariate GWAS uncovered underlying genetics of a root economics spectrum itself, possibly for the first time. Combining crop physiology with ecological theory provides a unique opportunity to advance understanding of both natural and agricultural ecosystems.
Coauthors: Haichao Guo – Noble Research Institute;Xue-feng Ma – Noble Research Institute