Single-Molecule Long-Read Sequencing of Avocado Generates Microsatellite Markers for Analyzing the Genetic Diversity in Avocado Germplasm

Abstract

Avocado (Persea americana Mill.) is an important fruit crop commercially grown in tropical and subtropical regions. Despite the importance of avocado, there is relatively little available genomic information regarding this fruit species. In this study, we functionally annotated the full-length avocado transcriptome sequence based on single-molecule real-time sequencing technology, and predicted the coding sequences (CDSs), transcription factors (TFs), and long non-coding RNA (lncRNA) sequences. Moreover, 76,777 simple sequence repeat (SSR) loci detected among the 42,096 SSR-containing transcript sequences were used to develop 149,733 expressed sequence tag (EST)-SSR markers. A subset of 100 EST-SSR markers was randomly chosen for an analysis that detected 15 polymorphicEST-SSR markers, with an average polymorphism information content of 0.45. These 15markers were able to clearly and effectively characterize46 avocado accessions based on geographical origin. In summary, our study is the first to generate a full-length transcriptome sequence and develop and analyze a set of EST-SSR markers in avocado. The application of third-generation sequencing techniques for developing SSR markers is a potentially powerful tool for genetic studies.