A New Clonal Propagation Protocol Develops Quality Root Systems in Chestnut

There is, at the present time, a great demand for chestnut rootstocks with improved resistance toPhytophthora cinnamomiRands in the nurseries. New genotypes are emerging from European chestnut breeding programs and the production of thriving plants to restore old orchards with low yields due to a high incidence of diseases, namely root rot, is necessary. Micropropagation is a useful technique for clonal propagation. Nevertheless, in vitro culture propagation is genotype-dependent. Consequently, the existing protocols may demonstrate poor reproducibility and low efficacy. Thus, the need to contribute to the development of new micropropagation protocols suitable for large production of emerging genotypes. As a contribution to fill this gap, a three-step protocol was developed by using new combinations of Murashige & Skoog, Woody Plant, and adapted modified Melin-Norkrans media in different stages of the propagation process. About 90% of shoots were rooted, and after three months of acclimatization, 85% of these plants survived and were capable of continuous growth in the field. Currently, this protocol is being used in the production of several hybrid genotypes (with improved resistance toP. cinnamomi), selected from our ongoing breeding program and also inCastanea sativaMill. andCastanea crenataSiebold and Zucc. species.