To isolate the plasma membrane intrinsic protein 2 (PIP2) gene and its promoter from mulberry (Morus multicaulis), and to analyse its expression under stress conditions using quantitative real-time polymerase chain reaction (qRT-PCR) analysis, the mulberry MmPIP2 gene was cloned and sequenced. The putative MmPIP2 protein was 282 amino acids long and contained Asn–Pro–Ala signature motifs. Phylogenetic analysis showed that MmPIP2 is highly conserved, exhibiting strong homology with other plant PIP2s. The 5′ flanking sequence was cloned by genome walking and numerous transcription factor binding sites were identified. qRT-PCR revealed that the expression levels of MmPIP2 differed with changes in abiotic stress, indicating that PIP2 is a multifunctional molecule in mulberry. Studying the molecular mechanisms behind adaptations to stress and strengthening stress tolerance in plants are of fundamental importance to mulberry production.

A full-length cDNA denominated as MmPOD12 for peroxidase in mulberry(Morus alba), an enzyme involved in the respiration, photosynthesis, and the oxidation of auxin, was cloned from 'Yu71-1' a variety of mulberry using a rapid amplification of terminal (RACE) approach. The full cDNA of MmPOD12 has1482 base pairs (bp) in length with an open reading frame (ORF) 1050 bp encoding a protein of 349 amino acids residues with a predicted molecular weight of 53.92 kDa and an isoelectric point of 9.35. Sequence analysis revealed that MmPOD12 shares homology with the Morus notabili (M. notabilis C.K.Schn) and has closely related to green plum, strawberry and pear. The expression patterns of MmPOD12 treated with drought, salt and hormones stresses were examined using real-time quantitative PCR (RT-qPCR). These experiments caused significant up-regulation of the expression of MmPOD12 under drought and salt stress. The highest expression level of MmPOD12 appeared at 2d for salt stress, and 7d for drought stress, while a significant fluctuation of MmPOD12 expression was detected after ABA and SA stresses. These findings provide a basis for future functional analyses of MmPOD12 gene in Mulberry.