The Role Of Autophagy In Anti-pathogen And Ethanol Stress Of Yeast

Fruits and vegetables could suffer a drop of immunocompetence after picking, and can be easily infected by penicillium, grey mold, sickle bacterial and so on. In addition to the economic loss, infected fruits and vegetables would do harm to the human health. Chemical fungicides is the main methods in the prevention and control of disease such infection. However, consumers are gradually repelling this method because of its toxic effect. Thus, it’s urgent to find green and safe prevention method. In recent years, antagonistic yeasts become a main biocontrol agent because of their green, natural and safe characters.Antagonistic yeasts first have to have a certain tolerance to the stress of the outside world. Based on previous research, the ethanol stress is the most stress that saccharomyces cerevisiae could suffer. Autophagy is a process of cell self-cleaning, which plays a key role in yeasts aging, death and resistance to various stresses. Autophagy is beneficial to the survival of the yeast under harmful conditions and it’s the research hotspot in recent years. However, relevant reports about whether autophagy is involved in saccharomyces cerevisiae’s ethanol stress and resistance to plant pathogens couldn’t be found. Therefore, this article focus on the effect of autophagy in yeast’s ethanol stress and resistance to plant pathogens, using deletion mutant of autophagy related genes atg1, atg8, atg11, atg32and saccharomyces cerevisiae wild type BY4742.The experimental results showed that the expression of macroautophagy and mitophagy related genes atg1, atg8, atg11, atg32were upregulated under the condition of ethanol stress. In YPD cultivation, the growth curve of yeasts that loss of autophagy related genes was similar to that of wild type. Under the condition of ethanol stress, the membrane integrity and livability of the four mutant yeasts types were lower than those of wild type, suggesting that the two are beneficial to maintain the the membrane integrity and livability of yeasts. ROS level was increased under ethanol stress in the four mutant yeasts types, indicating that macroautophagy and mitophagy contribute to the removal of ROS in yeasts. By flow cytometry instrument analysis, the amount of cells in S phase of mutant types under normal condition were higher than that of wild type, suggesting that the two kinds of autophagy were not beneficial to DNA synthesis under normal condition. Under ethanol stress, the amount of cells in S phase of ATG32bacterial strain was lower than that of wild type, while other mutant types were higher than that of wild type, indicating that mitophagy, rather than macroautophagy, contributes to DNA synthesis under ethanol stress.The study of cucumber sickle bacteria yeast antagonism suggests that the higher concentration of the yeasts, the stronger inhibiting effect yeasts to the fusarium, that is, concentration-dependent manner. The inhibiting effect of ATG1, ATG8mutant types were slightly lower than that of wild type, while that of ATG11, ATG32were obviously lower than that of wild type, indicating that in yeasts, macroaotophagy, especially mitophagy play an important role in inhibiting the growth of fusarium, contributing to exerting their inhibition effect. Morphological research found that when yeasts exist, the amount of fibrillae of spores of fusarium was obviously less than that of control and their weight decreased obviously too, indicating that the way of yeasts growth is inhibiting fusarium by competition for nutrients.The study of Penicillium yeast antagonism found that the higher concentration of the yeasts, the stronger inhibiting effect yeasts to the penicillium. The inhibiting effect of ATG1, ATG8, ATG11, ATG32mutant types were obviously lower than that of wild type, suggesting that macroautopahgy and mitophagy play an important role in inhibiting the growth of penicillium, contributing to exerting their inhibition effect.