Apoplastic barriers of Populus × canescens roots in reaction to different cultivation conditions and abiotic stress treatments

Abstract

Populus is an important tree genus frequently cultivated for economical purposes. However, the high sensitivity of poplars towards water deficit, drought, and salt accumulation significantly affects plant productivity and limits biomass yield. Various cultivation and abiotic stress conditions have been described to significantly induce the formation of apoplastic barriers (Casparian bands and suberin lamellae) in roots of different monocotyledonous crop species. Thus, this study aimed to investigate to which degree the roots of the dicotyledonous gray poplar (Populus × canescens) react to a set of selected cultivation conditions (hydroponics, aeroponics, or soil) and abiotic stress treatments (abscisic acid, oxygen deficiency) because a differing stress response could potentially help in explaining the observed higher stress susceptibility. The apoplastic barriers of poplar roots cultivated in different environments were analyzed by means of histochemistry and gas chromatography and compared to the available literature on monocotyledonous crop species. Overall, dicotyledonous poplar roots showed only a remarkably low induction or enhancement of apoplastic barriers in response to the different cultivation conditions and abiotic stress treatments. The genetic optimization (e.g., overexpression of biosynthesis key genes) of the apoplastic barrier development in poplar roots might result in more stress-tolerant cultivars in the future.

Suberin deficiency and its effect on the transport physiology of young poplar roots

“…Following previous studies focusing on the root development of the P . × canescens clone 84K (Grünhofer et al ., 2021, 2022b, 2023), two functional developmental zones important for the chemical suberin analysis could also be identified with 5‐wk‐old roots of INRA 717‐1B4. Zone A, defined by no observable endodermal suberization in the WT, ranged from 0% to 21.5% relative root length, and Zone B, characterized by patchy endodermal suberization, constituted the remaining 21.5–100%.…”