Rapidly Evolved Genes in Three Transcriptomes and Potential Roles of Pentatricopeptide Repeat Superfamily Proteins in Endangerment of .

genus (Tamaricaceae) is widely distributed across the desert and semi-desert regions of Northern China, playing a crucial role in the restoration and protection of desert ecosystems. Previous studies mainly focused on the physiological responses to environmental stresses; however, due to the limited availability of genomic information, the underlying mechanism of morphological and ecological differences among the species remains poorly understood. In this study, we presented the first catalog of expressed transcripts for , a sympatric species of xerophyte . We further performed the pair-wise transcriptome comparison to determine the conserved and divergent genes among , , and the relict recretohalophyte . Annotation of the 600 relatively conserved genes revealed that some common genetic modules are employed by the species to confront with salt and drought stresses in arid environment. Among the 250 genes showing strong signs of positive selection, eight pentatricopeptide repeat () superfamily protein genes were specifically identified, including seven genes in the vs. comparison and one gene in the vs. comparison, while the cyclin D3 gene was found in the vs. comparison. These findings suggest that genetic variations in genes may affect the fertility system or compromise the extent of organelle RNA editing in . The present study provides valuable genomic information for and preliminarily reveals the conserved genetic bases for the abiotic stress adaptation and interspecific divergent selection in the species. The rapidly evolved and genes provide new insights on the endangerment of and the leaf length difference among the species.