S04 - Session O1 - Micrografting in almond (Prunus dulcis) Portuguese varieties for production of disease-free plants

Authors: Ana Faustino, Rita Costa Pires, Sandra Caeiro, Armindo Rosa, António Marreiro, Jorge Canhoto, Sandra Correia, Liliana Marum *

Almond is an important tree nut crop ( Prunus dulcis , (Mill.) D.A. Webb) whose consumption has been increasing in the last years due to its nutritional value. In Portugal, new orchards are being installed in the Alentejo and Beira Interior regions, using commercial varieties. Portugal has a long history of almond production in other regions and the traditional varieties are known for the high quality of the fruits [1 ] . Almond trees are often infected with Prunus dwarf virus (PDV) and Prunus necrotic ringspot virus (PNRSV) that affect productivity and have been responsible for significant economic losses [2] . Micrografting allows the placement of a shoot explant of a specific variety onto a decapitated rootstock, in aseptic conditions. Some protocols have been described for commercial almond trees [3] , and recently our team initiate the establishment and optimization of in vitro protocol for Portuguese varieties. Different culture media supplemented with PGR have been tested to improve the micrografting of disease-free traditional varieties. Preliminary results demonstrated that the use of IBA (indole-3-butyric acid) improves the micrograft growth, healing rate, and rooting rate. The cultural conditions and media, and good contact between the scion and rootstock, seem to influence the success of micrografting. New studies are being performed in order to confirm the micropropagation of the plant viruses-free. The knowledge obtained with this work will allow the design of an efficient protocol for micrografting almond Portuguese varieties. This technique is being applied in several tree nuts not only for the production of disease-free plants, but also for rejuvenation of mature tissues and elimination of virus.