Comparative analysis of root sprouting and its vigour in temperate herbs: anatomical correlates and environmental predictors

Abstract

Background and Aims Root sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves both as a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, viz.; the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (i) whether the presence or absence of specific tissues in roots can promote or limit RS, and (ii) whether there is some relationship between RS ability, RS vigour and species niche. Methods We studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits, and the relationship between RS and parameters of species niche. Key Results One quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats. Conclusions Our study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS, ability and vigour, should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats.

Comparative root anatomy and root bud development after injury in two perennial herbs

“…Furthermore, our findings reinforce the observations of Bartušková et al . (2021), where all root buds from several adult RS species had bud traces along the xylem to the root centre. However, further analyses are required to test whether a similar pattern also occurs in other herbaceous species.…”

“…Two perennial herbs, the root‐sprouting Inula britannica and the non‐root‐sprouting I. salicina, were characterized by root anatomical differences regarding root bud presence, root vascular cylinder, vessel diameters and the degree of root maturation and presence of sclerified cells, which have also been found in other species with similar resprouting behaviour (Bartušková et al . 2021). Contrary to expectations, none of the previously mentioned characteristics were affected by plant injury.…”

“…2019; Bartušková et al . 2021). In woody plants, it was observed that root buds may be of two types with distinct anatomy.…”

“…While root‐sprouting species are characterized by secondary thickening of the roots and the formation of sclereids, non‐sprouting species have roots without secondary thickening and sclereids (Bartušková et al . 2021). Secondary tissues are formed after the activation of lateral meristems (vascular cambium and phellogen), which help the organ to grow in diameter and, together with sclereids, will make the root more lignified.…”

“…However, in herbs, no such difference was found for 46 temperate root‐sprouting species, and all root buds developed after injury formed bud traces contiguous with the centre of the root (Bartušková et al . 2021). However, it is not clear whether plant injury was the trigger for bud formation or only for bud regrowth into shoots in the studied plants because anatomical assessment was conducted 4 weeks after plant injury (Bartušková et al .…”