ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Biotechnology
Thidiazuron and trans zeatin riboside promote development of shoots and nodes in in vitro propagation of hops (Humulus lupulus L. var. lupulus)
Provisionally accepted
Maria Jenderek1,2*
Elise R. Staats1,2- 1USDA-ARS Plains Area, Fort Collins, United States
- 2USDA-ARS Plant and Animal Genetic Resources Preservation Unit, Fort Collins, United States
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Hops (Humulus lupulus L. var. lupulus) are dioecious, climbing plants considered as horticultural and industrial crop. They are propagated vegetatively by root cuttings and to a lesser extent by tissue cultures. Various plant growth regulators were applied in hops tissue culture propagation such as benzyladenine, kinetin, indole-3-acetic acid, thidazuron, zeatin, gibberellic acid, and some in combination with glucose. We have carried out in vitro propagation of three randomly selected genotypes (PI 546055, PI 558687 and PI 617389) from the USDA ARS hop germplasm collection to establish a procedure for developing large quantity of shoots, nodes and long main shoots using 15 treatments of plant growth regulators and glucose without plant growth regulators. The micropropagation was carried out in three propagation cycles lasting 4 wks each. The most shoots and nodes resulted from treatments with thidiazuron (15.9+1.34 shoots; 40.6+3.6 nodes). Literature reports successful use of this plant growth regulator in selected hop cultivars, but thidiazuron caused hyperhydricity in PI 546055. Occurrence of hyperhydricity in this accession seems to be genotype dependent. Hence its use in hops micropropagation should be discreet. The disorder was not observed in the other treatments. In the 3 .0 mg L-1 trans zeatin riboside treatment, the shoot number (8.4+1.34) and node number (24.9+3.6) was not far from the thidazuron treatments, and the length of the main shoots (9.3+0.92 cm) was not significantly different from the other treatments, except for the thidiazuron treatments. The 3.0 mg L-1 of trans zeatin riboside was the top treatment for micropropagation of the three hop accessions; this treatment will be used for a variety of accessions from the USDA hop germplasm collection; it may also be useful when large quantities of plantlets are needed for other purposes and the responsiveness to TDZ is unknown.
Keywords: doubleMagentavessels, Hyperhydricity, Main shoot length, Micropropagation, Nodes, Plant Growth Regulators, Shoots
Received: 27 Aug 2025; Accepted: 11 Dec 2025.
Copyright: © 2025 Jenderek and Staats. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Maria Jenderek
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