Prunus mume Sieb. et Zucc., P. armeniaca L., and P. salicina L. are economically important fruit trees in temperate regions. These species are taxonomically perplexing because of shared interspecific morphological traits and variation, which are mainly attributed to hybridization. The chloroplast is cytoplasmically inherited and often used for evolutionary studies. We sequenced the complete chloroplast genomes of P. mume, P. armeniaca, and P. salicina using Illumina sequencing followed by de novo assembly. The three chloroplast genomes exhibit a typical quadripartite structure with conserved genome arrangement, structure, and moderate divergence. The lengths of the genomes are 157,815, 157,797, and 157,916 bp, respectively. The length of the large single-copy region (LSC) region is 86,113, 86,283, and 86,122 bp, and the length of the SSC region is 18,916, 18,734, and 19,028 bp; the IR region is 26,393, 26,390, and 26,383 bp, respectively. Each of the three chloroplast genomes encodes 133 genes, including 94 protein-coding, 31 tRNA, and eight rRNA genes. Differential gene analysis for the three species revealed that trnY-ATA is a unique gene in P. armeniaca; in contrast, the gene trnI-TAT is only present in P. mume and P. salicina, though the position of the gene in these chloroplast genomes differs. Further comparative analysis of the complete chloroplast genome sequences revealed that the ORF genes and the sequences of linked regions rps16 and atpA, atpH and atpI, trnc-GCA and psbD, ycf3 and atpB, and rpL32 and ndhD are significantly different and may be used as molecular markers in taxonomic studies. Phylogenetic evolution analysis of the three species suggests that P. mume has a closer genetic relationship to P. armeniaca than to P. salicina.

Deubiquitinases are deubiquitinating enzymes (DUBs), which remove ubiquitin from proteins, thus regulating their proteasomal degradation, localization and activity. Here, we discuss DUBs as anti-cancer drug targets.

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Comparative and association analyses of the proteome and transcriptome for pear fruit development were conducted for the first time in this study. Pear fruit development involves complex physiological and biochemical processes, but there is still little knowledge available at proteomic and transcriptomic levels, which would be helpful for understanding the molecular mechanisms of fruit development and quality in pear. In our study, three important stages, including early development (S4-22), middle development (S6-27), and near ripening (S8-30), were investigated in 'Dangshansuli' by isobaric tags for relative and absolute quantitation (iTRAQ) labeling technology, identifying a total of 1,810 proteins during pear fruit development. The association analysis of proteins and transcript expression revealed 1,724, 1,722, and 1,718 associated proteins identified in stages S4-22, S6-27, and S8-30, respectively. A total of 237, 318, and 425 unique proteins were identified as differentially expressed during S4-22 vs S6-27, S6-27 vs S8-30, S4-22 vs S8-30, respectively, and the corresponding correlation coefficients of the overall differentially expressed proteins and transcripts data were 0.6336, 0.4113, and 0.7049. The phenylpropanoid biosynthesis pathway, which is related to lignin formation of pear fruit, was identified as a significantly enriched pathway during early stages of fruit development. Finally, a total of 35 important differentially expressed proteins related to fruit quality were identified, including three proteins related to sugar formation, seven proteins related to aroma synthesis, and sixteen proteins related to the formation of lignin. In addition, qRT-PCR verification provided further evidence to support differentially expressed gene selection. This study is the first to reveal protein and associated mRNA variations in pear during fruit development and quality conformation, and identify key genes and proteins helpful for future functional genomics studies, and provides gene resources for improvement of pear quality.