Cloning and expression of five heat shock protein genes in relation to cold hardening and development in the leafminer, Liriomyza sativa

The vegetable leafminer, Liriomyza sativae has spread worldwide, causing serious loss of agricultural productivity. Heat shock proteins (HSPs) play important roles in the environmental adaptation of various organisms, and to explore the functions of HSPs in relation to cold tolerance and development in L. sativae, three full-length cDNAs of small heat shock protein genes (ls-hsp19.5, ls-hsp20.8 and ls-hsp21.7) and two partial cDNAs of tcp1 (the hsp60 homolog, ls-tcp1α and ls-tcp1ζ) were cloned, and their transcriptional expression during cold hardening and development was examined by real time quantitative PCR. The open reading frames (ORFs) of ls-hsp19.5, ls-hsp20.8 and ls-hsp21.7 are 516, 543 and 573 bp in length, encoding proteins with molecular weights (M.W.) of 19.5, 20.8 and 21.7 kDa, respectively. The 956 and 323 bp partial cDNAs were respectively sequenced from ls-tcp1α and ls-tcp1ζ. The expression profiles during cold hardening revealed that ls-tcp1s did not respond to cold stress. However, the three small hsps were significantly induced by cold, and ls-hsp20.8 was more cold-sensitive than the others. These results suggest that different shsp members may be responsible for cold stresses of different intensity. The expression of hsps during developmental processes revealed that the mRNA levels of small hsps reached a peak in the pupal stage, whereas the levels of large hsps, including two ls-tcp1s, hsp60 and hsp90 increased gradually with the developmental process. These results suggest that, in addition to a heat shock response, these HSPs may be involved in the development of L. sativae.