STK1基因对山梨醇高渗胁迫下玉米大斑病菌菌丝生长和发育的调控

Regulation of mycelium growth and development of Setosphaeria turcica by STK1 gene under sorbitol hypertonic stress

【目的】明确STK1基因在山梨醇高渗胁迫条件下对玉米大斑病菌菌丝生长和发育的调控作用。【方法】将野生型菌株(WT)与STK1基因敲除突变体(KO)分别接种在不同山梨醇浓度的葡萄糖-蛋白胨(DPA)培养基上,对比其生长速度、菌落形态、菌丝形态的差异变化;并通过油红O染液进行菌丝细胞脂肪染色,观察脂类物质沉积的形态学变化。【结果】山梨醇高渗胁迫显著抑制了野生型菌株(WT)的菌落生长速度,但1.0 mol/L山梨醇对STK1基因敲除KO菌株的生长有显著的促进作用,这种促进作用随着山梨醇浓度的增加而迅速降低,山梨醇浓度增加至1.5~2.0mol/L时,菌落生长速度受到显著抑制,并且抑制程度显著高于WT菌株。显微观察菌丝细胞内容物,发现山梨醇高渗胁迫后,KO菌株的颗粒状物明显少于WT菌株。利用油红O染色观察菌丝细胞的脂类物质沉积情况,发现在山梨醇高渗胁迫条件下,KO菌株的脂滴数量远远少于WT菌株。【结论】山梨醇胁迫具有与盐胁迫不同的渗透调节机制,STK1基因可能通过调节脂类物质的合成及分布调控对山梨醇高渗透胁迫的调节。

【Objective】The STK1 gene is one important MAPK gene regulating the conidial development,osmotic stress and pathogenicity of Setosphaeria turcica.In this paper,its role in regulating hypha growth and development of S.turcica under sorbitol hypertonic stress was analyzed.【Method】Both the wild type strain（WT）and the knockout mutant（KO）of STK1 gene were grown on Dextrose Peptone Agar（DPA）medium with different concentrations of sorbitol to compare the differences in colony growth speed,colony morphism,and mycelia morphology.The lipid deposition on mycelium cells was observed by the oil red O staining method.【Result】The sorbitol hypertonic stress significantly inhibited the colony growth of the wild type strain（WT）,but that of KO mutant was accelerated under 1.0 mol/L sorbitol stress.The acceleration was rapidly decreased with the increase of sorbitol concentration.When the sorbitol concentration increased to 1.5-2.0 mol/L,the inhibition to KO mutant was much stronger than that to the WT strain.The granular material in mycelium cells of KO mutant was less than that of WT strain un-der sorbitol hypertonic stress under microscopic observation.The lipid deposition on mycelium cells was observed by the oil red O staining method,and the results showed that the number of lipid droplets in KO strains was far less than that of WT strain under sorbitol hypertonic stress.【Conclusion】Sorbitol stress and salt stress had different osmotic regulation mechanisms and STK1 gene possibly regulated the sorbitol hypertonic stress by controlling lipid synthesis.