Comparative Genomic Analysis of Gene Family, Cloning and Functional Characterization of Two Genes ( and ) in .

The (small auxin-up RNA) gene family is the biggest family of early auxin response genes in higher plants and has been associated with the control of a variety of biological processes. Although genes had been identified in several genomes, no systematic analysis of the gene family has been reported in Chinese white pear. In this study, comparative and systematic genomic analysis has been performed in the gene family and identified a total of 116 genes from the Chinese white pear. A phylogeny analysis revealed that the family could be classified into four groups. Further analysis of gene structure (introns/exons) and conserved motifs showed that they are diverse functions and -specific domains. The most frequent mechanisms are whole-genome duplication (WGD) and dispersed duplication (DSD), both of which may be important in the growth of the gene family in Chinese white pear. Moreover, cis-acting elements of the genes were found in promoter regions associated with the auxin-responsive elements that existed in most of the upstream sequences. Remarkably, the qRT-PCR and transcriptomic data indicated that and were significantly expressed in fruit ripening. Subsequently, subcellular localization experiments revealed that and were localized in the nucleus. Moreover, and were screened for functional verification, and Dangshan pear and frandi strawberry were transiently transformed. Finally, the effects of these two genes on stone cells and lignin were analyzed by phloroglucinol staining, Fourier infrared spectroscopy, and qRT-PCR. It was found that promoted the synthesis and accumulation of stone cells and lignin, inhibited the synthesis and accumulation of stone cells and lignin. In conclusion, these results indicate that and are predominantly responsible for lignin inhibit synthesis, which provides a basic mechanism for further study of gene functions.