42℃极端高温胁迫对木薯单爪螨(Mononychellus mcgregori)保护酶及热激蛋白基因表达的影响

木薯单爪螨(Mononychellus mcgregori)是新入侵中国的木薯重要害螨,原产地为南美洲,是一种热带土著害螨,近年来该螨扩张范围不断增大,对高温的适应性是其种群扩散的重要前提。本研究发现,42℃极端高温胁迫1 h后,木薯单爪螨成螨保护酶基因PPO、POD、As A-POD、CAT和Cu/Zn SOD的相对表达量显著升高,分别高达对照的5.19、4.38、152.23、321.42和3.41倍,且与其酶活性变化趋势存在一致性,酶活性值分别升高为对照的1.81、12.52、9.00、1.75和1.14倍。热激蛋白基因Hsp70的相对表达量显著升高,为对照的56.85倍。因此说明,保护酶POD、As A-POD、CAT、SOD和PPO以及热激蛋白Hsp70可能在木薯单爪螨应对高温胁迫中具有重要作用,高温下保护酶及热激蛋白Hsp70基因表达量及其活性的升高可能导致木薯单爪螨对高温的耐受能力逐渐增强,从而逐渐适应热区高温环境,并可能增强其后续的繁殖能力而使其种群不断增长,扩张范围不断增强。

Influence of Extreme High Temperature Exposure on Protective Enzymes and Hsp70 Gene Expression of Mononychellus mcgregori(Acari: Tetranychidae)

Cassava green mite Mononychellus mcgregori is a newly invasive pest mite of cassava in China.It was reported the first time in Danzhou,Hainan,China in 2008 and has since become more widespread.The origin of M.mcgregori is South America and as a tropical native mite,the adaptation to high temperature is the significant foundation for its occurrence and damage.The results showed that the relative expression of PPO,POD,AsA-POD,CA T and Cu/Zn SOD genes in M.mcgregori via RTFQ PCR increased in adults after they were exposed to extremely high temperature (42 ℃) for 1 h,which increased 5.19,4.38,152.23,321.42 and 3.41 times over that of the control,respectively,and were in accord with their enzyme activities (1.81,12.52,9.00,1.75 and 1.14 times over that of the control).And the relative expression of heat shock protein 70 (Hsp70) gene increased 56.85 times over that of the control.These results suggested that protective enzymes POD,AsA-POD,CAT and SOD were associate with the thermostability of M,mcgregori and they might have synergistic effects on protect the mite against toxic oxygen intermediates and perhaps were associate with the resistance of high temperature in M.mcgregori.The increasing of PPO gene expression was perhaps associated with the immunity improvement of the mite to high temperature stress.And the elevated expression of Hsp70 gene was perhaps related to the adaptation of M.mcgregori to high temperature.These results provide a theoretical basis and precondition for further research on the molecular mechanisms of the thermostability and ecological adaptability of M.mcgregori.