Characterization of the Pentatricopeptide Repeat (PPR) Gene Family and Its Role in Osmotic Stress Response.

The () superfamily is a large gene family in plants that regulates organelle RNA metabolism, which is important for plant growth and development. However, a genome-wide analysis of the gene family and its response to abiotic stress has not been reported for the relict woody plant . In this paper, we identified 650 genes from the genome. A phylogenetic analysis showed that the genes could roughly be divided into the P and PLS subfamilies. We found that 598 genes were widely distributed across 19 chromosomes. An intraspecies synteny analysis indicated that duplicated genes from segmental duplication contributed to the expansion of the gene family in the genome. In addition, we verified the relative expression of , , , and in the roots, stems, and leaves and found that all four genes had the highest expression in the leaves. By simulating a drought treatment and quantitative reverse transcription PCR (qRT-PCR) analysis, we confirmed the drought-responsive transcriptional changes in four genes, two of which responded to drought stress independent of endogenous ABA biosynthesis. Thus, our study provides a comprehensive analysis of the gene family. It contributes to research into their roles in this valuable tree species' growth, development, and stress resistance.