Analysis and characterization of the Aldehyde dehydrogenase (ALDH) gene superfamily in the desert moss Syntrichia caninervis in response to abiotic stress

Abstract

Syntrichia caninervis is desiccation-tolerant moss and a dominant species in biological soil crusts in the Gurbantunggut desert of Northwestern China. S. caninervis is being developed as a model moss for studying the molecular mechanisms of desiccation tolerance (DT) and as a source for stress-related genes germplasm. Aldehyde dehydrogenases (ALDHs) are a set of NAD (P)+ dependent enzymes that oxidize a wide range of endogenous and exogenous aromatic and aliphatic aldehydes into their corresponding non-toxic carboxylic acids. In the current study, we identified 15 ALDH genes from the moss S.caninervis, grouped them into eleven families based upon clearly established criteria. As determined by RT-qPCR, transcript abundance of ScALDH genes respond to drought, salinity, cold, and/or ABA treatment. ScALDH5F, ScALDH6B1, ScALDH7B1, ScALDH11A1 and ScALDH21A1 exhibited consistent up-regulation as compared to other transcripts. We selected four genes (ScALDH2B2, ScALDH10A1, ScALDH11A1 and ScALDH21A1) based upon sequence characteristics and qRT-PCR profiles, and subsequently cloned and transformed to E. coli strain where the transgenes conferred varying degree of drought and salt tolerance. The four purified ScALDH proteins indicated enzyme activities with aldehyde of C6-C9 carbon chain as substrates were more suitable than that of C1-C2 carbon chain, especially unsaturated aldehyde, all have their own special substrates.