Exploring genetic variation, oil and α-tocopherol content in avocado (Persea americana) from northwestern Mexico

The Hass cultivar of avocado is the most widely grown commercial cultivar in Mexico. Unfortunately, this cultivar is poorly adapted to the Mexican low-lands with hot dry climates characteristic of northwestern Mexico. Other well-adapted avocado accessions are available for these regions, but their nutritional traits and genetic diversity have yet to be explored. In this study, we analyze oil content, (alpha-tocopherol) and genetic variation among five local varieties from northwest Mexico that grow in high temperatures regimes in unfertilized soils and without any agronomic management. We report significant phenotypic variability in oil and alpha-tocopherol components in different accessions of avocado as determined by HPLC. Interestingly, we find higher alpha-tocopherol content (45.02-50.66 mu g/g of fresh pulp) in some local avocados compared to Hass (32.28 mu g/g of fresh pulp). The analyzed accessions represent a moderately polymorphic set of genotypes as measured by microsatellite (10 alleles by locus) and SNP (1 SNP every 164.4 bp) analysis of the VTE3 and VTE4 genes, implied in the biosynthesis of tocopherols. SNP data allowed also identifying differences between the local varieties and controls (Hass and the Mexican race accession). The variation observed at the genetic, morphologic and nutritional levels provide significant new information that may be valuable in selecting and developing avocado genotypes adapted to high-temperature environments.