Evaluation of the effect of different culture systems on photomixotrophic capacity during in vitro multiplication of pitahaya (Hylocereus undatus)

Abstract

Pitahaya (Hylocereus undatus) micropropagation is an alternative for obtaining invigorated plants with high phytosanitary quality. The objective of this research was to evaluate different culture systems on photomixotrophic capacity during in vitro multiplication and their effect on survival in the acclimatization stage of H. undatus. Different temporary immersion systems (TIS) were used: temporary immersion bioreactors (TIB), Ebb-and-Flow bioreactor, Recipient for Automated Temporary Immersion (RITA), and semi-solid (SS) culture medium. At 60 d of culture, the percentage of explant response, developmental variables, chlorophyll and carotene content, stomatal index (SI), percentage of closed stomata (CS), PEP (Phosphoenolpyruvate) and Rubisco (Ribulose-1,5-bisphosphate carboxylase oxygenase) content and the percentage of survival in the greenhouse acclimatization stage were evaluated. The culture systems with the highest percentage of response were the SS culture medium (96%), Ebb-and-Flow (93%) and RITA (90%). The Ebb-and-Flow and RITA bioreactors showed the highest number of shoots, with 9.5 and 9.0, respectively, the greatest length, with 2.62 and 2.71 cm, the highest chlorophyll, with 0.30 and 0.28 mg g–1 FW, and carotenoid content, with 2.25 and 2.20 mg g–1 FW. The SS medium culture system showed the highest SI with (57%), while the TIB had the highest CS, with (85%). The Ebb-and-Flow and RITA culture systems showed the highest PEP content, with 15 and 18 nmol g–1 FW, respectively; whereas, for Rubisco content, no differences were found in the different culture systems. The Ebb-and-Flow and RITA culture systems presented the highest survival rate, with 99.6% during acclimatization. The use of Ebb-and-Flow and RITA bioreactors are a biotechnological alternative for in vitro propagation of H. undatus and guarantee high survival rates during acclimatization without going through a rooting stage.