Producing Cereal Food under Drought: a Root-based Approach to Plant Improvement

Objective

Water is the most limiting environmental factor for agricultural production worldwide and climate change exacerbates this threat. Breeding plants with improved resistance to drought is therefore a priority. Although roots play a strategic role in plant drought responses, their traits have been poorly explored by breeders, primarily due to the challenges associated high-throughput phenotyping. In this PoC project, we propose exploiting a whole genome survey of root water transport capacity recently obtained in maize and transfer this knowledge to modify the water economy of plants under drought stress. To achieve this, we will utilise the physiological link between root hydraulics, plant transpiration and growth that was discovered in this species and show that it can represent a novel trait network to be utilised in cereal breeding programmes. We will explore a new pre-breeding design using a pyramid strategy with up to four independent Quantitative Trait Loci (QTLs). Relevant nearly-isogenic or mutant inbred lines and a related F2 population will be cultivated under drought stress in a high-throughput phenotyping platform and phenotyped for plant growth and transpiration using specialized image analysis and gas exchange devices. In addition, we will use genomic sequencing in a diversity panel of 245 maize inbred lines to characterize the allelic diversity of the corresponding genes and identify the alleles with the most pronounced effects on root hydraulics. These approaches aim to provide breeders with the most relevant genetic information. In future, information on more than 20 other root hydraulic QTLs may be exploited in similar way. Overall, the proposed breeding approaches can be implemented using either genome editing or conventional breeding (introgression of favorable alleles) in elite lines. Based on an as yet unexplored root trait, these approaches will enable the water economy of the elite lines to be tailored via haplotype-informed breeding.