Evolution of US maize (Zea mays L.) root architectural and anatomical phenes over the past 100 years corresponds to increased tolerance of nitrogen stress

Larry M. York, Tania Galindo-Castañeda, Jeffrey R. Schussler, Jonathan P. Lynch

Research output: Contribution to journalArticlepeer-review

152 Scopus citations

Abstract

Increasing the nitrogen use efficiency of maize is an important goal for food security and agricultural sustainability. In the past 100 years, maize breeding has focused on yield and above-ground phenes. Over this period, maize cultivation has changed from low fertilizer inputs and low population densities to intensive fertilization and dense populations. The authors hypothesized that through indirect selection the maize root system has evolved phenotypes suited to more intense competition for nitrogen. Sixteen maize varieties representing commercially successful lines over the past century were planted at two nitrogen levels and three planting densities. Root systems of the most recent material were 7 more shallow, had one less nodal root per whorl, had double the distance from nodal root emergence to lateral branching, and had 14% more metaxylem vessels, but total mextaxylem vessel area remained unchanged because individual metaxylem vessels had 12% less area. Plasticity was also observed in cortical phenes such as aerenchyma, which increased at greater population densities. Simulation modelling with SimRoot demonstrated that even these relatively small changes in root architecture and anatomy could increase maize shoot growth by 16% in a high density and high nitrogen environment. The authors concluded that evolution of maize root phenotypes over the past century is consistent with increasing nitrogen use efficiency. Introgression of more contrasting root phene states into the germplasm of elite maize and determination of the functional utility of these phene states in multiple agronomic conditions could contribute to future yield gains.

Original languageEnglish
Pages (from-to)2347-2358
Number of pages12
JournalJournal of Experimental Botany
Volume66
Issue number8
DOIs
StatePublished - Apr 1 2015
Externally publishedYes

Funding

We thank Dr Joseph Chimungu, Andrew Evensen, Dr Anthony Fernando, Dr Denise Fernando, Elizabeth Nottingham, Hannah Schneider, Robert Snyder, Michael Williams, Jennifer Yang, Ai Zhan, and Xinji Zhang for technical assistance. We thank Dr Carlos Messina and Dr Mark Cooper for their helpful discussions. DuPont Pioneer provided the seed. This research was supported by the National Science Foundation/Basic Research to Enhance Agricultural Development (grant no. 4184-UM-NSF-5380) and Agriculture and Food Research Initiative competitive grant no. 2014-67013-2157 of the USDA National Institute of Food and Agriculture to JPL.

Keywords

  • Anatomy
  • architecture
  • density
  • maize
  • nitrogen
  • phenotype
  • root

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