North Carolina State University researchers have successfully transferred an important gene from one compartment of a plant cell to another to produce tobacco plants that lack pollen and viable seeds, while otherwise growing normally. Their findings could lead to better ways of producing hybrid seeds to maximize crop productivity, or to introduce seedlessness in fruit species lacking the often-desired trait, such as raspberries, blackberries or muscadine grapes.
The researchers began the work in the energy-producing portion of a cell, the mitochondria. In plants, aberrations within the mitochondrial genome can be associated with the inability to make pollen, a trait known as cytoplasmic male sterility (CMS) that has been successfully exploited for the production of high-yielding hybrid seeds in many important crops. Naturally occurring CMS-based systems that are robust enough to facilitate commercial scale hybrid seed production are limited, however.
In their proof-of-concept study, the NC State researchers, together with colleagues from Precision BioSciences and Elo Life Systems, deployed a unique strategy to test whether the CMS trait could be generated in tobacco, a commonly used model species in plant research. The researchers initially took an essential mitochondrial gene called atp1 and moved it to the nucleus after placing it under the regulatory control of an element – known as a promoter – that they predicted would allow the transferred atp1 gene to be expressed in every cell of the plant except those responsible for producing pollen. The researchers then used genome editing tools to permanently remove the native atp1 gene from the mitochondria.