Genome-Wide Analysis of Pentatricopeptide Repeat Proteins in Gossypium Species

The PPR gene family is one of the largest gene families in plants, with 450 members in Arabidopsis and 477 in rice. Most PPR genes lack introns and encode PPR proteins containingtwo to 35 tandem repeats of 35 degenerate amino acids. The PPR gene family is further divided into the P subfamily and the PLS subfamily based on the PPR motif variation and a series of conserved C-terminal domains. As the PPR gene family is closely related to the function of mitochondria and chloroplasts in plants, the discovery of this family has quickly drawn widespread attention worldwide. In this study, PPR protein-coding genes are identified and classified into subfamilies and classes in four sequenced cotton species, i.e., Gossypium arboreum, G. raimondii, G. hirsutum and G. barbadense. A phylogenetic tree for each species is constructed and compared among the four species. Homologous and homeologous PPR genes are further identified for identification of sequence variations and evolutionary analysis. Candidate PPR genes for fertility restoration of cytoplasmic male sterility will be identified and analyzed.