A dry look at improving plant breeding in maize

A dry look at improving plant breeding in maize

By Jim Ruddock, Managing Editor

ARGOS8 variants generated by CRISPR–Cas9 improve maize grain yield under field drought stress conditions.

Shi J, Gao H, Wang H, Lafitte HR, Archibald RL, Yang M, Hakimi SM, Mo H, Habben JE (2017)

Plant Biotechnology Journal 15, 207 216 http://onlinelibrary.wiley.com/doi/10.1111/pbi.12603/abstract

Rapid population growth coupled with limited resources and climate change calls for innovation to keep pace at a similarly rapid rate. In this article Shi et al. describe research into CRISPR–Cas9-enabled crop improvements aimed at expanding genetic variation to enhance maize breeding for drought tolerance. Maize ARGOS8 gene negatively regulates ethylene responses and when ectopically over-expressed improves maize tolerance to drought stresses. CRISPR–Cas plant breeding technology develops improved seeds by using native characteristics available within the target crop. Using HDR-swap and HDRinsertion, facilitated by CRISPR–Cas9 genomeediting technology, the authors modified the regulatory elements of the ARGOS8 gene in maize and generated new ARGOS8 alleles which had different expression patterns from the native allele. Field trials demonstrated an increase in grain yield under water-limited stress during flowering, and no decrease in yield under optimal water availability. This study is important because it demonstrates that single endogenous genes can be modified using CRISPR–Cas9 technology to produce novel allelic variants that have a significantly positive effect on a complex trait such as drought tolerance. The results are of broad interest to researchers in plant genome engineering, demonstrating a new and easy way to breed abiotic stress tolerance in key crops, revealing a means to enhance the productivity of maize, and ultimately helping to meet the increasing global demands of food security.