Genetic Diversity and Population Structure Analysis in Avocado (Persea americana) Accessions of India

Avocado is an important fruit tree crop cultivated in more than 80 countries. It is a cross-pollinated species with a protogynous diurnally synchronous dichogamy (PDSD) flowering. Avocados were introduced into India in the early nineteenth century. Recently, the demand for avocados is increasing in the domestic and international markets due to the high nutritive value of the fruit. In India, wide morphological variations are observed in avocados due to the cross-pollinations. The comprehensive information on genetic diversity of Indian avocado is lacking. Understanding the genetic diversity existing in avocados is needed for germplasm conservation and crop improvement. Molecular markers are widely used for genetic characterization of germplasm. However, there are no reports on characterization of Indian avocado accessions using the microsatellite molecular markers. In the current study, the genetic diversity and population structure analysis of Indian avocado germplasm accessions were carried out using the genomic simple sequence repeats (gSSR) and expressed sequence tag (EST)-SSR markers. A high heterozygosity with an average of 0.74 was detected in the avocado accessions by the assayed SSR markers. The 83 avocado accessions were grouped into three major clusters in the genetic diversity analysis. Besides, a total of four subpopulations (K = 4) were identified in the STRUCTURE analysis. This is the first report of comprehensive characterization of Indian avocado accessions using the molecular markers.