Anatomy of absorptive roots in fine root system of different coffee species

The importance of studying root anatomical traits is related to their crucial roles in understanding root functions and root form–function correlations. In this regard the present study, within the EU-funded Bolero Project, aims to describe the main anatomical traits of absorptive roots in the fine root system, in different Coffea species kept under controlled conditions. The purpose is to reveal interspecific root anatomy differences and to deepen the knowledge of coffee fine root characteristics that have a key role in the carbon economy at both the plant and ecosystem level. Young plants (6-month-old) of several Coffea species, grown in horticultural trays under greenhouse conditions, were chosen for this study. Phenotypic characteristics of the whole plants and microscopy observations of absorptive roots were performed to highlight possible peculiarities. The primary tissues of absorptive roots, observed in transversal sections, were the same for all the species investigated, but revealed peculiar traits, such as the presence of short cells in the exodermis, typical of xerophytes and here observed in detail in coffee plants. The presence of multilayer cortical parenchyma that could affect root-biotic interactions was observed and for some coffee species it represents a strategy to reduce the metabolic cost of soil exploration. Some anatomical traits of absorptive roots put in evidence in this study have been discussed in view of a possible role played under stress conditions. The results of this study represent fertile ground for further investigation into the strategies adopted by root cells of different coffee species in response to abiotic or biotic stresses.