cDNA cloning of four Hsp genes from Agarophyton vermiculophyllum and transcription analysis in different phases

Agarophyton vermiculophyllum is an agarophytic red alga originating from Northeast Asia that successfully spread to Europe and North America in the last 20 years. In this study, three hsp70 genes (hsp70-1, hsp70-2, and hsp70-3) and one hsp90 gene were cloned, and real-time reverse transcription polymerase chain reaction (RT-qPCR) was used to measure their transcriptional levels in three kinds of thalli (tetrasporophytes, and male/female gametophytes) belonging to diploid or haploid phases in the life cycle of A. vermiculophyllum. The results show that the three Hsp70s in A. vermiculophyllum clustered into three different groups, and the locations of the putative Hsp70-1, Hsp70-2, and Hsp70-3 were in the cytoplasm, endoplasmic reticulum and chloroplast, respectively, according to their sequences. Beside on the same research, the putative Hsp90 was supposed to have a cytoplasmic location. The RT-qPCR results show that the three hsp70 genes were highly upregulated in gametophytes as compared to tetrasporophytes but the transcriptional level of hsp90 did not show such a significant increase. The chloroplast hsp70-3 exhibited the highest upregulation and the transcriptional level increased more than 570 fold in female gametophytes, and 17 fold in male gametophytes, compared with tetrasporophytes. Therefore, cpHsp70-3 might act more like a chaperon molecule involved in haploid development under natural condition, while Hsp70-1 and Hsp70-2 were more active in stress resistance.