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Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms
- Robert, Christelle A. M., Ferrieri, Richard A., Schirmer, Stefanie, Babst, Benjamin A., Schueller, Michael J., Machado, Ricardo A.R., Arce, Carla C.M., Hibbard, Bruce E., Giershenzon, Jonathan, Turlings, Ted C.J., Erb, Matthias
- Plant, cell and environment 2014 v.37 no.11 pp. 2613-2622
- Diabrotica virgifera, autoradiography, beta-fructofuranosidase, carbon, carbon dioxide, compensatory growth, corn, herbivores, irrigation rates, isotope labeling, leaves, meristems, radionuclides, resistance mechanisms, root systems, roots, seedlings, shoots, stems
- Upon attack by leaf-herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated this aspect in maize seedlings infested by the specialist root herbivore Diabrotica virgifera. By using radioactive 11CO2 in combination with autoradiography and gamma counting of tissue sections, we demonstrate that root-attacked maize plants allocate more new 11C carbon from source leaves to stems, but not to roots. Reduced meristematic activity and reduced invertase activity in attacked maize root systems are identified as possible drivers of the reallocation response. The increased allocation of photoassimilates to stems is shown to be associated with a marked thickening of these tissues and increased growth of stem-borne crown roots in induced plants. The strong quantitative correlation between stem thickness and root re-growth across different watering levels suggests that retaining the carbon in the shoots may help root-attacked plants to compensate for the loss of below ground tissues. Taken together, our results indicate that induced tolerance may be an important strategy of plants to withstand below ground attack. Furthermore, root-herbivore induced carbon reallocation needs to be taken into account when studying plant-mediated interactions between herbivores.