Evaluation of Avocado Germplasm Using Microsatellite Markers

Abstract

<jats:p>Three horticultural races of avocado (<jats:italic>Persea americana</jats:italic> Mill.) are known: Guatemalan, Mexican, and West Indian. Each race has unique characteristics and current commercial varieties have been selected from within the races or from interracial hybrids. Using 14 microsatellite loci we investigated the genetic variation among 224 accessions (394 plants) maintained at the National Germplasm Repository (NGR) in Miami, Fla., and a set of 34 clones from the University of California South Coast Field Station (SCFS) located in Irvine, Calif. The 14 microsatellite loci had an average of 18.8 alleles per locus and average unbiased genetic diversity was 0.83. The total propagation error in the collection, i.e., plants that had been incorrectly labeled or grafted, was estimated to be 7.0%. Although many unique alleles did exist, no useful race-specific markers were found. A general concordance between the horticultural race and the clusters obtained from molecular data was observed. Principal Coordinate Analysis (PCA) grouped the Guatemalan and Mexican races into two distinct clusters. The West Indian also grouped into a unique major cluster but with an outlying group. Using the PCA a change in the racial designation or interracial hybrid status for 50 accessions (19.7%) is proposed. The unbiased gene diversity estimate was highest in the Mexican and Guatemalan races and lower in the West Indian group. This demonstrates the need to collect more of the West Indian germplasm to broaden the genetic diversity and to emphasize the identification of individuals conferring resistance to Phytophthora Root Rot (PRR).</jats:p>

Analysis of clonal germplasm from five Saccharum species: S. barberi, S. robustum, S. officinarum, S. sinense and S. spontaneum. A study of inter- and intra species relationships using microsatellite markers

“…This problem seems to exist in other clonally propagated horticultural crops, as demonstrated in avocado (Persea americana Mill.) by Schnell et al (2003) and in Mango (Schnell et al 2006), though to a lesser extent. Turnbull et al (2004) presented a more detailed discussion of how mislabeling can occur over the lifespan of a clonally propagated variety.…”

Some aspects of avocado (Persea americana Mill.) diversity and domestication in Mesoamerica

“…These figures constitute a forest growing around the coffin of the king, but it is not a wild forest. Instead, the ancestors emerge with fruit trees that the Maya grew and tended around their houses (Schele 1974(Schele , 1998.…”

An EST-SSR-based linkage map for Persea americana Mill. (avocado)

“…Avocado has been proposed to be the result of an ancient polyploid event (Chanderbali et al 2008). However, evidence from analyses of germplasm collections and seedling populations using simple sequence repeat (SSR) markers have demonstrated diploid inheritance for most markers although some primer pairs have amplified more than one locus (Schnell et al 2003;Borrone et al 2007Borrone et al , 2008.…”