SETIS™ bioreactor increases in vitro multiplication and shoot length in vanilla (Vanilla planifolia Jacks. Ex Andrews)

Abstract

Temporary immersion systems (TIS) are extensively used for the in-vitro regeneration of plants. These systems have been proposed as a suitable technique for propagating vanilla (Vanilla planifolia Jacks) for commercial purposes. This study compares three different culture systems for the micropropagation of vanilla: semi-solid (SS), liquid medium under partial immersion (PI), and temporary immersion (TI) using the SETIS™ bioreactor. In all cases, the culture systems included the Murashige and Skoog culture medium (MS) added with 30 g L−1 sucrose and 9.55 μM benzyladenine (BA). The number of shoots per explant, as well as shoot length, number of leaves per shoot, fresh weight, dry weight, stomatal index, and chlorophyll content were recorded after four weeks of culture. Also, the ex-vitro survival rate was estimated for all the culture systems investigated. The highest values of shoot proliferation and development were observed in TI (11.41 shoots/explant), followed by PI (6.53), and SS (3.76); the highest fresh and dry weights were obtained in TI, followed by PI, and SS. A higher synthesis of chlorophyll was observed in PI relative to TI and SS. Stomata showed a similar distribution and morphology in leaves of plants under the different culture systems. T1 showed peak values of the percentage of closed stomata and stomatal index. The highest percent survival during acclimatization was observed in TI (98%), followed by PI (85%), and SS (75%). At the end of the micropropagation process, 227 plants of V. planifolia were obtained in SS, 500 plants in PI and 3026 in TI. In conclusion, the SETIS ™ bioreactor improves the physiological conditions of in-vitro development and is an alternative for the propagation of V. planifolia at large scale.