Why is root sprouting not more common among plants? Phytohormonal clues and ecological correlates

Martínková J., Klimeš A., Motyka V., Adamec L., Dobrev P.I., Filepová R., Gaudinová A., Lacek J., Marešová I., Klimešová J.

Keywords: Auxin/cytokinin ratio, buds, carbohydrate storage, disturbance, growth, phytohormones
Abstract: Root sprouting (RS) species can regenerate from even small root fragments. The root buds are usually well protected against disturbance because they are deep in the soil, and injury oftentimes boosts root sprouting. Despite these obvious advantages, only 10% of plants exhibit RS ability. Are there specific ecophysiological barriers to RS ability? We set up a controlled experiment with ten congeneric pairs of herbs differing in RS ability and exposed them to severe aboveground biomass removal and assessed how RS and non-RS species differ in biomass production, root nitrogen and phosphorus content, and root tissue carbohydrate concentrations and whether phytohormone profiles explain variation in RS ability. No differences were observed in regenerated biomass three months after biomass removal, although RS species had lower root dry matter content, lower root nitrogen content, higher soluble sugar content, and a lower auxin-to-cytokinin ratio than non-RS species. RS and non-RS herbs differed in root tissue carbohydrate concentrations, which suggests that RS species, apart from having RS ability, might be better prepared for disturbance due to the availability of stored energy and carbon. Presumably, the key barrier to the more frequent occurrence of RS ability in the herbaceous plants studied here is a low auxin-to-cytokinin ratio, which is necessary to induce RS but is likely non-existent in most plants in order to avoid the risk of developmental deformities.
DOI: 10.1016/j.envexpbot.2022.105147
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IEB authors: Petre I. Dobrev, Roberta Filepová, Alena Gaudinová, Jozef Lacek, Václav Motyka