Root growth and root system architecture: Potential for enhancing rapeseed tolerance to heat stress in a changing climate

Increased climatic variability is expected across the globe, and will lead to more frequent extreme heat and drought stress events. This is anticipated to have a devastating impact on plant growth, development, and yield formation of rapeseed/canola, an important oilseed crop for human consumption and a renewable feedstock for biodiesel production. The growing demand for rapeseed/canola and the challenge of global climate change on sustainable production ask for an urgent development of strategies to substantially improve crop yields and product quality. The impacts of heat and drought or their interactive effects on crop plants are typically being studied under the controlled or field conditions. In view of this, developing varieties with enhanced tolerance to heat and drought stresses emerges as the most sustainable solution towards improving crop productivity in a climate change scenario. Meanwhile, unraveling the genetic basis and the targeted identification of molecular networks using modern biotechnology, has led to a better understanding of the genetic makeup to the stress tolerance mechanisms and has provided plant breeders with new tools for efficient breeding program, targeting high yield potentials under both favourable and stressful environments. In this review, we will provide an update on recent advances on the response of rapeseed/canola to heat and drought stresses, from molecular level of signal transduction, up to phenotyping the whole-plant and agroecosystem scales. Roots, as the ‘hidden half’ of the plants, play a central role in acquisition of water and nutrients (improving water and nutrient use efficiencies) as well as maintaining crop standability (resistance to lodging, and tolerance to heat and drought stresses) to achieve sustainable production under changing climate. Therefore, this review will also provide readers with conventional and modern methodologies for root system architecture exploration as well as current understanding of root-specific tolerance mechanisms to abiotic stress.