The First Complete Chloroplast Genome Sequence and Phylogenetic Analysis of Pistachio (Pistacia vera)

Abstract

Pistachio is one of the most economically important nut crops worldwide. However, there are no reports describing the chloroplast genome of this important fruit tree. In this investigation, we assembled and characterized the complete pistachio chloroplast sequence. The Pistacia vera chloroplast genome was 160,598 bp in size, similar to other members of Anacardiaceae (149,011–172,199 bp) and exhibited the typical four section structure, including a large single copy region (88,174 bp), a small single copy region (19,330 bp), and a pair of inverted repeats regions (26,547 bp). The genome contains 121 genes comprised of 87 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Thirteen intron-containing genes were identified in the genome wherein two genes had more than two introns. The genomic patterns of GC content resembled those for other Anacardiaceae. P. vera displayed the highest number of simple sequence repeats (SSRs) among the genera studied, which may be useful for molecular marker development and future population studies. Amino acid analysis revealed that Leucine is the most frequent (10.69%) amino acid in the chloroplast genome followed by Isoleucine (8.53%) and Serine (7.77%). Cysteine (1.30%) and Tryptophan (1.74%) were the least frequent amino acids. Phylogenetic analysis revealed P. vera is most like its taxonomically close relative P. weinmaniifolia, followed by Rhus chinensis; all placed taxonomically in the tribe Rhoeae. Members of Anacardiaceae were most closely related to Rhoeae, followed by members of Spondieae. The reports of this chloroplast genome will be useful for future conservation studies, genetic evaluation and breeding of P. vera, and more comprehensive phylogenetic analysis of the Pistacia species and its closely-related genera.