Abstract Basic leucine zipper (bZIP) is a conserved transcription factor (TF) widely present in eukaryotes, and it plays an important role in regulating plant growth and stress responses. To better understand the white pear bZIP gene family, comprehensive bioinformatics analysis of the pear genome was performed. A total of 84 PbbZIP genes were identified, which were divided into 13 subfamilies by phylogenetic analysis. The 84 PbbZIP genes were all located in the nucleus, and 77 of those genes were unevenly distributed across the 17 chromosomes of white pear. The other 7 PbbZIP genes were located on the scaffold. Subsequent expression profile analysis showed that PbbZIP genes in exocarp were significantly upregulated or downregulated in ‘Huangguan’ pear with brown spot (BS) compared with healthy pear and in response to hormonal treatment with gibberellin A3 (GA3). These results provide helpful insights into the characteristics of PbbZIP genes and their responses to BS in ‘Huangguan’ pear.

Abstract The plant genes encoding ABCGs that have been identified to date play a role in suberin formation in response to abiotic and biotic stress. In the present study, 80 ABCG genes were identified in ‘Dangshansuli’ Chinese white pear and designated as PbABCGs. Based on the structural characteristics and phylogenetic analysis, the PbABCG family genes could be classified into seven main groups: classes A-G. Segmental and dispersed duplications were the primary forces underlying the PbABCG gene family expansion in ‘Dangshansuli’ pear. Most of the PbABCG duplicated gene pairs date to the recent whole-genome duplication that occurred 30~45 million years ago. Purifying selection has also played a critical role in the evolution of the ABCG genes. Ten PbABCG genes screened in the transcriptome of ‘Dangshansuli’ pear and its russet mutant ‘Xiusu’ were validated, and the expression levels of the PbABCG genes exhibited significant differences at different stages. The results presented here will undoubtedly be useful for better understanding of the complexity of the PbABCG gene family and will facilitate the functional characterization of suberin formation in the russet mutant.