ARS | Publication request: MICROGRAFTING OF ASBVD-INFECTED AVOCADO (PERSEA AMERICANA MILL.) PLANTS.

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2003
Publication Date: January 27, 2004
Citation: Suarez, I.E., Schnell II, R.J., Kuhn, D.N., Litz, R.E. 2004. Micrografting of ASBVd-infected Avocado (Persea americana Mill.) Plants. Plant Cell, Tissue and Organ Culture. 80:179-185.

Interpretive Summary: The elimination of viruses and viroids by shoot tip grafting has been successful in some crops such as citrus. In avocado sunblotch viroid is persistent and cleaning up infected genetic stocks is not currently possible. This research utilized a micrografting technique to try to eliminate ASBVd from infected meristems by out growing the viroid. Unfortunately, we were not able to eliminate the viroid from the meristem using the micrografting technique. This technique is useful for rapid propagation of new genotypes for commercial production but cannot be used to eliminate ASBVd from infected germplasm.

Technical Abstract: Shoot tips (meristem plus 2-3 leaf primordial) from in vitro germinated avocado seedlings of 2 ASBVd-infected cultivars were in vitro micrografted onto decapitated seedlings from 2 ASBVd-free cultivars, and plants were recovered. Shoot tips consisted of two different sizes, i.e.: < 0.5 mm long and > than 0.5 mm long but less than 1 mm. The recovered plants were indexed using RT-PCR for ASBVd infection and amplified products were cloned and sequenced. More plants (58.8%) were recovered from scions >0.5mm than from those that were <0.5 mm (10.3%). The results of the RT-PCR showed that ASBVd replicated in the micrografts irrespective of the scion size, while no ASBVd was detected in micrografts from plants that tested negative. The cloning and sequencing of the amplified DNA fragments from a single micrograft, permitted the isolation of 3 ASBVd variants confirming that ASBVd is not eliminated using in vitro micrografting.