A genetic diversity study of Persea

We present the molecular analysis of 41 accessions of the genus Persea (avocado) and a related genus: Persea cinerascens (1), Persea schiedeana (1), Persea floccosa (1), Persea parvifolia (1), Persea lingue (1), Persea meyeniana (1), Persea americana (25), Beilschmiedia anay (1), Persea hybrids (8), and an unidentified Persea sp. (1). Statistical analyses were performed based on amplified random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) bands that were recorded as discrete variables, 1 for present and 0 for absent, which formed the basis for phenograms to display genetic trees. The RAPD system generated a total of 144 polymorphic bands, with an average of 36 bands per primer. Their contributions ranged from 16.4 to 31.3%, while their polymorphic information content (PIC) ranged from 0.28 to 0.40, with an average of 0.34. For the ISSRs, 114 polymorphic bands were obtained, averaging 28.5 bands per primer, with a contribution range of 22.5 to 27.6% and a PIC range of 0.20 to 0.23 and an average of 0.22. RAPDs distinguished two main branches: branch A grouped Universidad Autónoma del Estado de México (UAEM) accessions and hybrids belonging to the Mexican race (P. americana var. drymifolia) and P. floccosa, while the others grouped in branch B. The latter accessions belong to the subgenus Eriodaphne (“aguacatillos”) and, associated with these, B. anay (anayo), a genus related to Persea and predominant in Puebla, Mexico. Because of their ability to identify specific polymorphisms within the genome, ISSRs distinguished almost a similar group in all individuals, making it difficult to distinguish them, but the closeness of P. cinerascens, P. floccosa and P. schiedeana is remarkable. Individuals share considerable genome similarity in spite of their distinct geographical origins. A new type of Persea was located in the states of México and Oaxaca.