agronomy Article Physiological and Molecular Characterization of New Apricot Cultivars Grafted on Different Prunus Rootstocks Patricia Irisarri 1,2 , Pilar Errea 1,2 and Ana Pina 1,2,* 1 Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda, Montañana 930, 50059 Zaragoza, Spain;
[email protected] (P.I.);
[email protected] (P.E.) 2 Instituto Agroalimentario de Aragón–IA2, CITA-Universidad de Zaragoza, 50013 Zaragoza, Spain * Correspondence:
[email protected] Abstract: In the last years, an important renewal of plant material from different breeding pro- grams is taking place in apricot in order to improve resistance to biotic stresses, extension of the harvest season, fruit quality, and productivity. However, the graft compatibility of many of these cultivars with most popular Prunus rootstocks is unknown, and this is an essential agronomical trait for their better performance and longevity. Hence, the introduction of new cultivars requires knowledge of the extent and nature of incompatibility reactions before releasing these cultivars on the market. In this study, the determination of graft compatibility was carried out in 13 new apricot cultivars grafted on four Prunus rootstocks: ‘Marianna2624’ (P. cerasifera × P. musoniana), ‘Miragreen’ (P. cerasifera × P. davidiana), ‘Mirared’ (P. cerasifera × Nemared), and ‘Montclar’ (P. persica L. seedlings) at early stages of development. By combining cytomorphological, anatomical, and phenylalanine ammonia-lyase (PAL) gene expression analysis at the graft interface, as well as differ- ent vegetative parameters, the results highlighted ‘Miragreen’ and ‘Mirared’ as promising rootstocks for apricot, showing the highest degree of compatibility with more than 90% of the apricot cultivars. Citation: Irisarri, P.; Errea, P.; Pina, These results provide useful information for breeders and growers by selecting the most suitable A.