Embriogênese somática em mandioquinha-salsa (Arracacia xanthorrhiza Bancroft)

Abstract

Arracacha (Arracacia xanthorrhiza) is a species of Andean origin whose roots have high economic importance and nutritional value. However, because it is vegetatively propagated through shoots, the crop may present problems related to seedling sanitary quality, mainly due to the dissemination of diseases such as viral and bacterial infections. In this context, the establishment of a somatic embryogenesis protocol enables large-scale mass propagation with the production of plantlets of high phytosanitary quality. Therefore, the objective of this study was to investigate a protocol for somatic embryo induction via callus production using the Thin Cell Layer (TCL) technique in different explants of A. xanthorrhiza established in vitro. Analyses were conducted through a bibliometric survey and laboratory-based callus induction experiments. For the bibliometric analysis, keywords were used to search the Web of Science Core Collection database, aiming to identify studies on somatic embryogenesis in different vegetable species, as well as their protocols and establishment strategies. In the laboratory, three experiments were conducted in which explants of A. xanthorrhiza (leaf and basal, middle, and apical regions of the petiole), previously established in vitro, were cultured under different concentrations of 2,4-D (0; 0.020; 0.040; 0.060; and 0.080 μM, and 0; 10; 20; 30; and 40 μM) for initial callus induction and subsequently transferred to other culture media to induce somatic embryogenesis. The bibliometric analysis revealed an increase over time in the number of publications, driven by the diversity of horticultural species studied and the protocols established. These studies highlight somatic embryogenesis as a relevant tool in plant biotechnology, contributing significantly to advances in clonal propagation, genetic improvement, and plant biodiversity conservation. Callus induction was favored at all tested concentrations when explants from the basal region of the petiole were used, showing greater callus formation capacity, acquisition of embryogenic competence, and plant regeneration. The concentrations of 0.040 and 20 μM 2,4-D stood out for initial callus induction and subsequent somatic embryogenesis. The Thin Cell Layer technique is capable of inducing in vitro development, following the organogenesis and somatic embryogenesis pathways, mainly in leaf explants and petiole base explants, generating calluses, roots, shoots, and somatic embryos. Furthermore, embryogenic competence could be achieved both with the addition of the cytokinin kinetin (KIN) and in the absence of plant growth regulators.