Expression and Functional Analysis of the PaPIP1-2 Gene during Dormancy and Germination Periods of Kernel-Using Apricot (Prunus armeniaca L.)

Aquaporins play a crucial role in helping water molecules move across cell membranes. While some studies have examined the role of AQPs in model plants like Arabidopsis, their impact on the ability of non-model plants to withstand environmental stress is largely unknown. In this study, we have explored the functions of the PaPIP1-2 gene, which encodes a protein called PIP, in apricot kernels (Prunus armeniaca L.). Our findings reveal how the PaPIP1-2 gene behaves during both dormancy and sprouting phases. Using a network analysis, we identified its interaction with six genes related to cold resistance. The mRNA levels of PaAQP genes, which co-express with cold resistance genes, remain consistent throughout different stages of P. armeniaca flower bud development, including physiological dormancy (PD), ecological dormancy (ED), sprouting period (SP), and germination stage (GS). Furthermore, our investigation of the location of the GFP-tagged PaPIP1-2 protein showed that it is mainly found in the cell membrane. Yeast strains with overexpressed PaPIP1-2 exhibited improved cold resistance and higher protein content. Similarly, when we overexpressed PaPIP1-2 in Arabidopsis, it enhanced the growth of these transgenic plants under cold stress. This improvement was associated with reduced levels of MDA (malondialdehyde); decreased ion leakage; increased proline accumulation; superoxide dismutase (SOD) activity; and the expression of cold resistance genes like AtPUB26, AtBTF3L, AtEBF1-1, and AtRAV1, compared with the wild-type plants. In summary, our results highlight the role of the P. armeniaca PaPIP1-2 gene in enhancing cold resistance and its importance in the dormancy and germination stages.