Breeding crops for enhanced roots to mitigate against climate change without compromising yield

Abstract

Boosting soil carbon by adding it to the soil, is among climate mitigation strategies. In a viewpoint more than a decade ago, Kell (2011) proposed plant breeding as a tool to develop varieties with larger underground biomass as a method to store carbon in the soil and reverse the trends of increasing atmospheric CO2 concentrations. To this date, the only evidence showing breeding for root traits is in rice. Wheat is well suited to serve this purpose because it is an important crop for food security and is the crop with highest cultivated area in the world. In this study, we developed breeding populations by crossing ‘Penny’ (a donor parent with large root) and ‘Yecora’ (a small root cultivar). Aboveground and belowground biomass partitioning, carbon content, and grain weight were studied in soil under controlled environment. Selection candidates differed significantly for all traits except carbon content. Broad-sense heritability for shoot biomass was 0.75 and for all other traits were equal or above 0.94. The root biomass ranged 0.43–7.72 g, averaging 2.13 g. A considerable range of root/shoot ratio was observed the selection candidates from 0.029 to 0.341, averaging 0.10. Based on LSD test, 13 out of 23 progenies tested in the replicated experiment, had significantly greater root biomass than ‘Yecora’. Among those, there were lines that produced equal or greater grain weight than “Yecora”. BC2 129, for example, showed 8.6-folds greater root biomass compared with ‘Yecora’ yet produced grain weight with no significant difference with that of ‘Yecora’. Similarly, BC2 147, BC2 165, BC2 137, showed 3.1-folds, 2.4-folds, 2.3-folds, respectively, greater root biomass but similar grain weights compared with ‘Yecora’. These lines showed significantly greater root/shoot ratios. Roots collected at physiological maturity showed 40.2%, on average, carbon content per dry biomass. This study showed that given one cycle of breeding involving a donor germplasm from genebank wheat root system can be manipulated to develop germplasm for grain production and simultaneously mitigating climate change by allocating more carbon in soil.