Cloning and sequence analysis of the Δ1-pyrroline-5-carboxylate synthase gene (MP5CS) from mulberry (Morus alba) and patterns of MP5CS gene expression under abiotic stress conditions

Drought is an important plant growth-limiting factor. Delta 1-Pyrroline-5-carboxylate synthase (P5CS) is a key enzyme closely related to proline biosynthesis under drought stress. A full-length cDNA sequence from the P5CS gene in mulberry (Morus alba), designated MP5CS (GenBank Accession Number KC202259), was cloned. MP5CS was 2190 bp in length, contained a 47-bp 5'-untranslated region (5'-UTR) and a 648-bp 3'-UTR, and encoded 497 amino acids with a predicted molecular weight of 53.92 kDa and an isoelectric point of 9.35. Phylogenetic analysis based on P5CS gene sequences from various species showed that mulberry was closely related to Boehmeria nivea, Malus hupehensis, Gossypium arboreum, and Euonymus japonicas. MP5CS gene expression under drought or salt stress conditions was quantified by quantitative real-time reverse transcription-polymerase chain reaction (RT-qPCR). The results showed that both abiotic stresses caused a significant upregulation in the expression of MP5CS in leaves compared to a normal growth environment. These data provide a better understanding of the molecular basis of signal transduction during stress responses in mulberry trees.