Inoculation of somatic embryos of sweet potato with an arbuscular mycorrhizal fungus improves embryo survival and plantlet formation

Responses of somatic embryos of sweet potato (Ipomoea batata (L.) Poir., cv . White Star) at different developmental stages to in vitro inoculation wit h Glomus etunicatum (Becker and Gerdemann) (isolate INVAM FL329) were evalu ated. Somatic embryos were grown in glass tubes containing sterilized vermi culite and sand. A layer of natrosol plus White's medium was used as a carr ier for arbuscular mycorrhizal (AM) fungal spores. Survival of embryos inoc ulated with AM fungi was significantly (P < 0.05) greater than that of noni noculated embryos at the rooted-cotyledonary-torpedo and rooted-elongated-t orpedo developmental stages. Mycorrhizae significantly (P < 0.05) increased plantlet formation only when inoculation occurred at the rooted-elongated- torpedo developmental stage. The growth stage at which the embryos were ins erted into the glass tubes exerted a significant influence upon plantlet fo rmation, and plantlet formation was further enhanced by inoculation with G. etunicatum. Plantlet formation was greatest at the rooted-elongated-torped o stage. These results demonstrate that inoculation of somatic embryos with AM fungi improves embryo survival and plantlet formation, and could enhanc e use of somatic embryos as synthetic seeds.