Molecular cloning and characterization of five genes encoding pentatricopeptide repeat proteins from Upland cotton (Gossypium hirsutum L.).

The pentatricopeptide repeat (PPR) protein family is one of the largest and most complex families in plants. These proteins contain multiple 35-amino acid repeats that are proposed to form a super helix capable of binding RNA. PPR proteins have been implicated in many crucial functions broadly involving organelle biogenesis and plant development. In this study, we identified many genes encoding PPR protein in Upland cotton through an extensive survey of the database of Gossypium hirsutum. Furthermore, we isolated five full-length cDNA of PPR genes from G. hirsutum 0-613-2R which were named GhPPR1-GhPPR5. Domain analysis revealed that the deduced amino acid sequences of GhPPR1-5 contained from 5 to 10 PPR motifs and those PPR proteins were divided into two different PPR subfamilies. GhPPR1-2 belonged to the PLS subfamily and GhPPR3-5 belonged to the P subfamily. Phylogenetic analysis of the five GhPPR proteins and 18 other plant PPR proteins also revealed that the same subfamily clustered together. All five GhPPR genes were differentially but constitutively expressed in roots, stems, leaves, pollens, and fibers based on the gene expression analysis by real-time quantitative RT-PCR. This study is the first report and analysis of genes encoding PPR proteins in cotton.