Is the bacterial leaf nodule symbiosis obligate for Psychotria umbellata? The development of a Burkholderia-free host plant.

Embryo culture is a cultivation technique with a high success rate for the development of Burkholderia-free plants of P. umbellata. The increased growth rate in vitro when the specific endophyte is present cannot be explained by possible benefits put forward in previous studies. This might indicate that the benefits of the endosymbiosis are not yet completely understood.