부산대학교 도서관

Δ8-sphingolipid desaturase is characterized by itsability to catalyze desaturation at the C8 position of the longchainbase of sphingolipids in plants. No previous studieshave been conducted on genes encoding Δ8-sphingolipiddesaturases in the woody plant Populus tomentosa. In thisstudy, three genes that encode Δ8-sphingolipid desaturasewere isolated fromP. tomentosa. Among these genes, PtD8Aand PtD8B showed high sequence similarity; whereas PtD8Cexhibited large sequence divergence.RT-PCRresults showedthat PtD8A and PtD8B were expressed in all tissues detected,whereas PtD8C was not expressed in roots. Heterologousexpression in yeast revealed that PtD8A/B/C were functionalΔ8-sphingolipid desaturases, and can catalyze the C18-phytosphingeninedesaturation to produce 8(Z)- and 8(E)-C18-phytosphingenine.However, the conversion rate and ratios ofthe two products differed. Compared with control cells,transgenic yeasts expressing PtD8A/B/C exhibited enhancedaluminum tolerance. Our findings further elucidated thebiochemical functions and evolutionary history ofΔ8-sphingolipid desaturases in plants. Candidate genes forbreeding new poplar germplasm resources with enhancedtolerance ability to aluminium were also provided.