Expression Analysis of MiSTPP5 Gene in Cold Stress and Different Tissues of Macadamia integrifolia

The PP1 family of serine/threonine phosphatase plays important roles in plant growth and development and response to stress. In order to provide a theoretical basis for further study on PP1 family genes in growth and development of Macadamia integrifolia and their molecular mechanism of cold resistance, the expression patterns of MiSTPP5 gene in cold stress and the different tissues of macadamia were analyzed. In this study, MiSTPP5 gene was cloned from macadamia by RT-PCR, and its coding protein was analyzed by bioinformatics. Expression patterns of MiSTPP5 gene in cold stress and the different tissues of macadamia were detected by real-time fluorescent quantitative PCR. The results showed that MiSTPP5 was a stable hydrophilic protein and non-secreted transmembrane protein, containing the typical domain MPP＿PP1＿PPKL of PP1 family. MiSTPP5 was mainly phosphorylated by serine residues, which may be located in the cytoplasm（up to 65%）. The secondary and 3 D main components of MiSTPP5 were α-helix, random coil and extended strand. MiSTPP5 gene was expressed in the roots, stems, leaves, flowers and small fruits of macadamia, which had the highest expression in leaves and the lowest expression in roots. Expression level of MiSTPP5 gene in leaves was increased under cold stress, with an “up-down-up-down” expression pattern. MiSTPP5 gene was expressed in different tissues of macadamia, and was up-regulated by cold stress.