Genome-Wide Identification of Stress-Associated Proteins (SAPs) Encoding A20/AN1 Zinc Finger in Almond (Prunus dulcis) and Their Differential Expression during Fruit Development

Stress-associated proteins (SAPs) are zinc finger proteins involved in the regulation of various stresses in a variety of plant species. A total of nine PdSAP genes were identified in Prunus dulcis. Phylogenetic and synteny analyses were performed to analyze the homology and evolutionary relationship of PdSAP genes. The functions of PdSAP genes were assessed by further analyses, including cis-regulatory elements, gene duplication, gene ontology, gene structure, subcellular localization, and motif pattern. This study found that PdSAP genes were unevenly distributed on chromosomes 2, 3, 6, and 7. Phylogenetic analysis of PdSAP genes with Arabidopsis thaliana and Oryza sativa suggested that six subgroups have a similar pattern of AN1 and A20 domains in each subgroup. PdSAP genes lacked duplicated blocks. The majority of PdSAP genes were localized in the nucleus region. Three hormonal and five stress cis-regulatory elements were found in the upstream promoter region of the PdSAP gene family. RNA-seq analysis revealed differential gene expression of PdSAP genes at days 12, 17, 22, 27, 32, and 37 of fruitlet development after flowering. This study identifies the SAP genes in P. dulcis and also provides insights into the expression of PdSAP genes in abnormal fruitlets with diapause atrophic growth at various developmental stages.