Comparing apoplastic root barrier formation and morphology in six crop species cultivated in soil vs. hydroponics

Cultivation medium affects apoplastic root barrier formation, gene expression, and morphology across crops, showing that soil growth compared to hydroponics strengthens suberization and lignification while altering plant structural traits. Hydroponic cultivation is commonly used in plant physiology studies; however, studies involving soil are rare. The response of 3 monocotyledonous and 3 dicotyledonous species to cultivation in soil compared with that to cultivation in hydroponic solution was investigated along with the quantification of relevant morphological parameters. The root anatomy was studied with the help of histochemical and microscopic analyses. Root suberin and lignin content were quantified via gas chromatography and mass spectrometry. Transcriptional changes were assessed via RNA-Seq analyses which compared the two growth conditions of barley plants. The results revealed that the plants of all the species cultivated in soil presented significantly longer roots and higher suberin and lignin contents. The above-ground organs of the plants grown in the hydroponic solution presented greater biomass accumulation, with greater shoot dry weights and leaf surface areas. We conclude that across a range of crop genera, the different physicochemical characteristics of the two cultivation media have a pronounced influence on plant morphology, root system architecture, and apoplastic barrier formation.