Adventitious shoot organogenesis and encapsulation technology in hop (Humulus lupulus L.)

Due to the increasing interest of growers in hop cultivation, there is a rising demand for hop plants that is not fully satisfied by nursery activity. Biotechnological methods and, specifically, in vitro propagation, could offer new opportunities to overcome these limitations, allowing the production of a great number of plantlets, in reduced space and independently of the season. In this research, organogenesis from two types of explant, petioles and internodes, and, for the first time to our knowledge, unipolar explants encapsulation have been studied to evaluate alternative methods for hop propagation and to try to satisfy hop nursery need. Our results confirmed the possibility of resorting to organogenesis as a propagation method, only if a precise and continuous check of somaclonal variation is carried out, due to the occurrence of a small percentage of tetraploids. Moreover, hop microcuttings were demonstrated to be a suitable starting material for encapsulation; indeed, in less than one month, it was possible to obtain a very high regrowth (up to 100%) and conversion (up to 82%). These results represent a first step towards the application of this technology to hop, also for other purposes, such as short and long term preservation.