Following advances in genetics, genomics, and phenotyping, trait selection in breeding is limited by our ability to understand interactions within the plant and with the environment, and to identify traits of most relevance to the target population of environments. We propose an integrated approach that combines insights from crop modelling, physiology, genetics, and breeding to characterize traits valuable for yield gain in the target population of environments, develop relevant high-throughput phenotyping platforms, and identify genetic controls and their value in production environments. This presentation will use transpiration efficiency (biomass produced per unit of water used) in wheat as an example of a complex trait of interest to illustrate how the approach can guide modelling, phenotyping, and selection in a breeding programme. Transpiration efficiency was identified as a valuable target to improve crops in major producing regions. Phenotyping platforms were built to study the physiology and genetics of transpiration efficiency. Genetic variations for this trait were partly correlated to water saving at high evaporative demand. Associated molecular markers were identified repetitively across trials and in different genetic backgrounds. Promising genotypes with higher transpiration efficiency than modern varieties were also identified as potential parents for further crossing and selection to produce more crop per drop.

We anticipate that the proposed approach, by integrating insights from diverse disciplines, can increase the resource use efficiency of breeding programmes for improving yield gains in target populations of environments in current and future climates.

Xm-50134

Exploring drought tolerance in diverse wheat genetic resources based on early vigour and yield

Yuzhou Lan1, Aakash Chawade1, Ramune Kuktaite1, Eva Johansson1

1The Swedish University of Agricultural Sciences, Alnarp, Sweden

Global climate condition is changing noticeably and increased drought events are predicted across the world. Thus, the sustainability of the future wheat production is challenged, and improvement of yield under drought is urgently needed. This work aimed to study the early vigour, and investigate the effects of drought stress on wheat until maturity. Wheat materials of wide genetic background (modern, old and wheat-rye introgression) were used in two experiments. In the image-based early root and shoot assay, more vigourous early root growth was found in old and introgression genotypes with 1R and 1RS than in modern and introgression genotypes with 2R, indicating the presence of genes contributing to longer root in the genome of old genotypes and on the rye chromosome 1R and 1RS. No correlation was found between early root and shoot traits, which suggested that early root and shoot growth of wheat might be regulated by separate genetic mechanisms. From the pot experiment under controlled conditions (biotron) evaluating 13 traits, the chromosome 3R was found to contribute to higher early drought tolerance while no clear pattern of the genetic background was found for late drought tolerance. Based on the genotypes with the highest stress tolerance index of yield, it was suggested that root biomass, grains per plant and spikes per plant might explain the high tolerance to early drought while 1000-grain weight, flag leaf area might explain the high tolerance to late drought in wheat.

The importance of early root vigour was recognized in the present study as an important character in wheat breeding for tolerance to climate-change-induced drought. To secure the sustainability and improve the resilience of wheat, suitable genes need to be searched for in old Swedish lines and on the 1RS chromosome of wheat-rye introgression lines. At maturity, yield performance is always the most important characteristic. Our results emphasize that yield of wheat can be decomposed into several yield-contributing traits and combining yield and other yield-contributing traits might help achieve more effective results than selecting drought-tolerant lines based on yield alone.