Challenges of modifying root traits in crops for agriculture

•Root architecture and function are important for yield and stress tolerance.•Root function has been modified using genetic engineering to improve crop stress tolerance and yield.•New methods are being developed to more rapidly phenotype roots in situ and ex situ.•Improving methods to phenotype roots poses the greatest future challenge.

Roots play an essential role in the acquisition of water and minerals from soils. Measuring crop root architecture and assaying for changes in function can be challenging, but examples have emerged showing that modifications to roots result in higher yield and increased stress tolerance. In this review, we focus mainly on the molecular genetic advances that have been made in altering root system architecture and function in crop plants, as well as phenotyping methods. The future for the modification of crop plant roots looks promising based on recent advances, but there are also important challenges ahead.