[Cloning and functional analysis of heat shock protein <i>Hsp70</i> from <i>Sclerotinia sclerotiorum</i>].

To clarify the roles of the heat shock protein gene <i>Hsp70</i> in the sclerotial formation and pathogenicity of <i>Sclerotinia sclerotiorum</i>, we employed reverse transcription PCR (RT-PCR) to clone <i>Hsp70</i> from <i>S</i>. <i>sclerotiorum</i> and performed sequence analysis. Quantitative real-time PCR (qRT-PCR) was employed to determine the relative expression levels of <i>Hsp70</i> at different growth stages and under the stress induced by cyclic adenosine monophosphate (cAMP) and low and high temperatures. The thermal stability of Hsp70 was measured. The <i>Agrobacterium</i>-mediated method was employed to construct the <i>Hsp70</i>-silenced strain. The pathogenicity and fungicide resistance of strains were tested by inoculation in detached rapeseed leaves and cultivation in the media containing procymidone and thiophanate-methyl, respectively. The results showed that the cloned <i>Hsp70</i> had a total length of 1 890 bp and close relationship with the <i>Hsp70</i> gene of <i>Ciborinia</i>. <i>Hsp70</i> showcased the highest expression level in sclerotia, which was more than 30 times higher than that in hyphae. The cAMP stress significantly induced the expression of <i>Hsp70</i>. The expression level of <i>Hsp70</i> showed an increasing-decreasing-increasing trend at 40 ℃ and no significant change at 4 ℃. Recombinant strain with high expression of Hsp70 showed good thermal stability. The <i>Hsp70-</i>silenced transformant did not form sclerotia, with decreased pathogenicity and fungicide resistance. This study reveals that Hsp70 plays an important role in the sclerotial formation and stress resistance of <i>S</i>. <i>sclerotium</i>, providing reference for further in-depth research on the biological roles of Hsp70 in <i>S</i>. <i>sclerotium</i>.