Abstract:

The peach SAP genes were identified using bioinformatics methods to determine their structural characteristics and expression patterns following stress alleviation. Results showed that 11 PpSAP family members were identified in the peach genome，with molecular weights ranging from 16 268.42 Da（PpSAP3）to 31 983.27 Da（PpSAP8）. Only three genes PpSAP4，PpSAP8，and PpSAP9 contained introns. Subcellular localization predictions indicated that most members are localized in the nucleus. Phylogenetic analysis revealed that PpSAP proteins can be classified into four groups：ⅠA，ⅠC，ⅡA，and ⅡB. Most PpSAP family members contain A20-AN1 domains，and proteins within the same group exhibit similar motif distributions. cis-Acting element analysis suggested that PpSAPs are primarily associated with light，hormone，and abiotic stress responses. Moreover，tandem duplication events contributed to the expansion of the PpSAP gene family. GO enrichment analysis identified 13 GO terms for PpSAPs，while a protein-protein interaction network indicated interactions between seven PpSAP members and four other proteins. miRNA interaction analysis identified 175 miRNAs targeting PpSAP proteins，among which the miR172 family showed specific interactions with multiple PpSAP members. qRT-PCR analysis of PpSAP expression in peach rootstocks（Baihua Shantao，Zhongtao Kangzhen 1，SH，GF677）and Prunus cerasifera rootstocks（Li 1，Li 3，Li 5，RA）after mitigation of abiotic stress revealed that under drought stress，PpSAP4 showed high expression in Li 3 and in GF677 treated with Spd or PEG，PpSAP6 was highly expressed in Li 1 treated with Spd，while PpSAP7 and PpSAP8 were significantly upregulated in Li 3 treated with PEG，and PpSAP9 was notably expressed in SH treated with Spd. Under low-temperature stress，PpSAP3 exhibited significant expression in Li 5 and RA treated with ALA，RA treated with Spd，and SH and RA treated with PEG；PpSAP4 reached its highest expression level（1 404.05）in GF677 treated with PEG；PpSAP8 showed high expression in Li 5 and RA after treatment with ALA or Spd. Under saline-alkali stress，PpSAP1 was highly expressed in Zhongtao Kangzhen 1 treated with ALA，PpSAP6 was significantly upregulated in Li 1 treated with ALA，while PpSAP9 showed notable expression in both SH treated with ALA and GF677 treated with PEG. These results indicate that the exogenous mitigators ALA，Spd，and PEG can specifically induce high expression of key PpSAP genes，and their regulatory effects vary significantly depending on the rootstock type and stress environment. In conclusion，PpSAP is hypothesized to be a key gene family involved in mitigating abiotic stress.

Key words: peach, rootstock, SAP gene family, bioinformatics, abiotic stress