Investigating trehalose synthesis genes after cold acclimation in the Antarctic nematode sp. DAW1.

sp. DAW1 is a freeze-tolerant Antarctic nematode which survives extensive intracellular ice formation. The molecular mechanisms of this extreme adaptation are still poorly understood. We recently showed that desiccation-enhanced RNA interference (RNAi) soaking can be used in conjunction with quantitative polymerase chain reaction (qPCR) to screen for phenotypes associated with reduced expression of candidate genes in sp. DAW1. Here, we present the use of this approach to investigate the role of trehalose synthesis genes in this remarkable organism. Previous studies have shown that acclimating sp. DAW1 at 5°C before freezing or desiccation substantially enhances survival. In this study, the expression of and other genes associated with trehalose metabolism, as well as , and , in cold-acclimated and non-acclimated nematodes was analyzed using qPCR. and were significantly upregulated after cold acclimation, indicating an inducible expression in the cold adaptation of sp. DAW1. The role of trehalose synthesis genes in sp. DAW1 was further investigated by RNAi. Compared to the controls, -treated and cold-acclimated nematodes showed a significant decrease in mRNA, but no change in trehalose content or freezing survival. The involvement of two other trehalose synthesis genes ( and ) was also investigated. These findings provide the first functional genomic investigation of trehalose synthesis genes in the non-model organism sp. DAW1. The presence of several trehalose synthesis genes with different RNAi sensitivities suggests the existence of multiple backup systems in sp. DAW1, underlining the importance of this sugar in preparation for freezing.