The Δ1-pyrroline-5-carboxylate synthetase family performs diverse physiological functions in stress responses in pear ( Pyrus betulifolia )

Δ1-Pyrroline-5-carboxylate synthetase (P5CS) acts as the rate-limiting enzyme in the biosynthesis of proline in plants. Although P5CS plays an essential role in plant responses to environmental stresses, its biological functions remain largely unclear in pear ( ). In the present study, 11 putative pear ( ) were identified by comprehensive bioinformatics analysis and classified into five subfamilies. Segmental and tandem duplications contributed to the expansion and evolution of the gene family. Various cis-acting elements associated with plant development, hormone responses, and/or stress responses were identified in the promoters of genes. To investigate the regulatory roles of genes in response to abiotic and biotic stresses, gene expression patterns in publicly available data were explored. The tissue-specific expressional dynamics of genes indicate potentially important roles in pear growth and development. Their spatiotemporal expression patterns suggest key functions in multiple environmental stress responses. Transcriptome and real-time quantitative PCR analyses revealed that most genes exhibited distinct expression patterns in response to drought, waterlogging, salinity-alkalinity, heat, cold, and infection by and . The results provide insight into the versatile functions of the gene family in stress responses. The findings may assist further exploration of the physiological functions of genes for the development and enhancement of stress tolerance in pear and other fruits.