Regeneration of West Indian limes (Citrus aurantifolia) containing genes for decreased seed set

Transgenic lime plants (Citrus aurantifolia) containing genes for decreased seed set were obtained from seedling hypocotyl and epicotyl segments by Agrobacterium-mediated gene transfer. Etiolation of germinating seedlings was used as a conditioner to improve shoot regeneration, and co-cultivation with Agrobacterium in the dark improved transformation efficiency. Most transformants were obtained from hypocotyl and epicotyl segments closest to the cotyledons (2.9%–4.1%). Escapes were high (66%–91%) and putative transformants were identified by polymerase chain reaction (PCR) prior to in vitro grafting on etiolated rough lemon or lime seedling rootstocks. Transgenic limes were established in soil 12–14 weeks from the start of the procedure. Following growth of several new leaves the copy number of the inserted genes was determined. Selected lines were propagated by budding on mature rough lemon rootstock. Because limes have a shorter juvenile period, the efficacy of the inserted genes can be determined prior to their introduction to cultivars with longer juvenile periods that are currently difficult to transform.