plants Review Recent Advances in Adventitious Root Formation in Chestnut Jesús M. Vielba, Nieves Vidal , M. Carmen San José, Saleta Rico and Conchi Sánchez * Department of Plant Physiology, Instituto de Investigaciones Agrobiológicas de Galicia, Consejo Superior de Investigaciones Científicas, 15705 Santiago de Compostela, Spain;
[email protected] (J.M.V.);
[email protected] (N.V.);
[email protected] (M.C.S.J.);
[email protected] (S.R.) * Correspondence:
[email protected]; Tel.: +34-981590958 Received: 7 September 2020; Accepted: 5 November 2020; Published: 11 November 2020 Abstract: The genus Castanea includes several tree species that are relevant because of their geographical extension and their multipurpose character, that includes nut and timber production. However, commercial exploitation of the trees is hindered by several factors, particularly by their limited regeneration ability. Regardless of recent advances, there exists a serious limitation for the propagation of elite genotypes of chestnut due to decline of rooting ability as the tree ages. In the present review, we summarize the research developed in this genus during the last three decades concerning the formation of adventitious roots (ARs). Focusing on cuttings and in vitro microshoots, we gather the information available on several species, particularly C. sativa, C. dentata and the hybrid C. sativa C. crenata, and analyze the influence of several factors on the achievements of the × applied protocols, including genotype, auxin treatment, light regime and rooting media. We also pay attention to the acclimation phase, as well as compile the information available about biochemical and molecular related aspects. Furthermore, we considerate promising biotechnological approaches that might enable the improvement of the current protocols.