Newly discovered trait helps plants grow deeper roots in dry, compacted soils

A previously unknown root trait allows some cereal plants to grow deeper roots capable of punching through dry, hard, compacted soils, according to Penn State researchers, who suggest that harnessing the inherited characteristic could lead to crops better able to deal with a changing climate. The trait helps corn, wheat and barley grow deeper roots, which is important for drought tolerance, nitrogen efficiency and carbon sequestration.

MCS phenotype

Roots with the newly discovered MCS (multiseriate cortical sclerenchyma) genotype have a greater concentration of lignin. More lignin gives the MCS roots greater tensile strength and greater root tip bending force compared to non-MCS genotypes. This added rigidity helps roots penetrate hard soil layers.

And this is important for growers, since plants with roots that are able to penetrate hard soil and forage deeper have an advantage in capturing water and nutrients. This leads to increased yield in drought or low soil fertility.

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Called multiseriate cortical sclerenchyma by the researchers — or MCS — the phenotype is characterized by small cells with thick walls just beneath the surface of the roots, as shown by these images captured by the researchers using laser ablation tomography. Roots with the MCS genotype have a greater concentration of lignin — an organic polymer that lends rigidity. – Photo: Hannah Schneider/Penn State

Field experiments

The Penn State study included both field and greenhouse components to assess root-penetration ability in compacted soils. Scientists conducted two field experiments to study root growth. Researchers grew six corn genotypes contrasting in root lignin content. Each field experiment involved compaction and noncompaction treatments.Twelve wheat genotypes and six corn genotypes also were grown in a greenhouse at the University Park campus.

Trait can be selected in breeding programs

Genetic variation for MCS was found in each of the cereals examined by the researchers, and heritability was relatively high, they reported, suggesting that this trait can be selected in breeding programs. Of the plant lines reviewed in this study, MCS was present in 30 to 50% of modern corn, wheat and barley cultivars.

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Lead researcher Hannah Schneider using laser ablation tomography – known as LAT – to visualize the anatomy of roots from plants in the study. Researchers using LAT can measure the light spectra given off by different cells cut by the laser to differentiate between various tissues. – Photo: Penn State

The implications of corn crops growing deeper roots to range farther for water and nutrients – and as a consequence producing larger yields – would be immense in regions where the populace is food-insecure. That is especially true in the face of a changing climate that is making vast areas more drought-prone, and in the face of soil compaction.

Increased yields in cereal crops

Researcher Hannah Schneider said: “We observe MCS in corn, wheat, barley and many other cereal crops, and our work suggests that many of the benefits of MCS may be analogous across different species,” she said. “MCS could be an important trait for stress tolerance and increased yields in cereal crops.”