Development of Phytophthora root rot-resistant avocado rootstocks for the Caribbean

James W. Borrone, Helen A Violi, Randy Ploetz, Raymond J. Schnell, Cecile T. Olano


Phytophtora root rot (PRR), caused by Phytophthora cinnamomi Rands, poses the greatest limitation to avocado production worldwide. Through a collaborative effort between researchers at the USDA-ARS facility in Miami and the University of Florida in Homestead, PRR-resistant avocado (Persea americana) rootstocks are being developed for the Caribbean. Avocado breeding presents several challenges. These include a long regeneration time (4-15 years) and the low efficiency of controlled pollinations. To overcome these challenges we will: i) increase the number of accessions from the Caribbean in breeding blocks; ii) screen large numbers of half-sib and fullsib seedling progeny in controlled greenhouse and field trials; iii) genetically characterize parents of PRR-tolerant and -susceptible progeny with molecular markers and iv) with the identified markers, develop marker-assisted selection protocols for resistance.


Phytophthora cinnamomi; Persea Americana; avocado; Phytophthora root rot; marker assisted selection; germplasm

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283