Cloning Of Hsp90 And Hsp20 Genes From The Diamondback Moth, Plutella Xylostella (L.) And Their Expression Under Heat Stress

Diamondback moth (DBM) is a destructive pest of cruciferous crops in the world. In this study, hsp90 and hsp20 genes from DBM were cloned by RT-PCR. The sequence analysis showed that the 2357bp full length of hsp90 cDNA contained a 2154bp open reading frame (ORF) that encoded 718 amino acids with PI 4.48. The deduced protein had a computed molecular mass of 82.460kDa. hsp20 had a full length of 600bp and contained 525bp open reading frame (ORF) that encoded 174 amino acids with PI 6.51. The deduced protein had a computed molecular mass of 19.64 kDa.The deduced amino acids of hsp90 had five highly conserved polypeptides: NKEIFLRELISNSSDALDKI、LGTIAKS、IGQFGVGFYSCYLVADR>IKLYVRRVFI �'� GVVDSEDLPLNISRE. The phylogenetic tree was created from the alignments of the amino acid sequences, and the analysis revealed that hsp90 of DMB is more than 90% identical to hsp90 from Bombyx mori、helicoverpa armigera、Argynnis paphia、 Spodoptera litura、Mamestra brassicae、cydia pomonella. The deduced amino acids of hsp20 had a typical a crystal domain. The phylogenetic tree was created from the alignments of the amino acid sequences, and the analysis revealed that hsp20 of DMB is 66%-75% identical to hsp20 from Danaus plexippus、Bombyx mori、 Mamestra brassicae-. Sesamia nonagrioides.The expression of hsp90 and hsp20 from DMB (larva and adult) under heat stress (33.5,37,42,47,50℃)were studied. The results showed that the expression level of hsp90 and hsp20 increased significantly when the larva and adult of DMB were pretreated with high temperation. With the increase of pretreated temperation, the expression of hsp90 and hsp20 reached the peak value at 42℃, and the extent of up-regulation (compared to 25℃) at 42℃ was significantly higher than that at 37℃ and 33.5℃.The expression of hsp90 in adult stage was significantly higher than that in larva stage at the same temperation, while the expression of hsp20 in adult stage was lower than that in larva stage. The results indicated that HSP90 and HSP20 could protect DMB from heat stress.