Analysis Of Fatty Acids Desaturase Gene Experssion And Autioxidant Enzyme Activitiesunder High Temperature Stress In Chrysanthemum

Chrysanthemum is perennial herbaceous perennial root flowers,widely used in city landscape.High temperature stress is an important impact factor of affect the plant,measuring the chrysanthemum of fatty acid desaturases gene expression in root and leaf of the trend,correlation,and the response of antioxidant enzyme indicators,known the response mechanism of chrysanthemum under high temperature stress.This study using the chrysanthemum varieties of ‘Jinlongtengyun’as test materials,selected the six processing temperature: 28℃,31℃,34℃,37℃,40℃ and 43℃,and selected four time gradient in each processing temperature: 0.5 h,3 h,12 h and 24 h.Measuring the antioxidant enzymes SOD,POD,CAT activity and MDA content,analysis of the test index changes,and discusses the chrysanthemum to fatty acids desaturases gene expression under high temperature and the change of antioxidant enzyme index,describe the respond patterns under high temperature stress.The main research conclusions are as follows:(1)Cm SAD,Cm FAD2,Cm FAD7 gene expression quantity in leaf and root were increased at first and then decrease with the temperature increase,Cm SAD and Cm FAD7 gene expression quantity in root are higher than leaf,the peak in root respectively are 2 times and 1.9 times than leaf,this results do not match the previous studies of low temperature condition chrysanthemum expression pattern.Cm FAD7 expression in leaf is far higher than the root,the peak in leaf are 56.7 times than root.The change trend of each gene expression quantity over time is differ,Cm SAD and Cm FAD2 expression decreased with increasing processing time,Cm FAD7 expression had no significant change over time.The most significant influenced by temperature is Cm SAD in root,the root of the Cm FAD7 genes is affected by temperature is minimal;and the highest relative expression is Cm FAD2 in leaf,9.55.Overall,the light high temperature stress can lead to chrysanthemum fatty acids desaturases gene expression quantity rise;Moderate and severe high temperature stress can lead to decreased expression,thus improve the degree of saturation of fatty acids,improve the phase transition temperature.(2)Relativity analysis was carried out on chrysanthemum three fatty acids desaturases gene expression under the same processing time:Cm FAD2 expression was significant relevant with Cm FAD7;Cm SAD was correlate with Cm FAD2 but no statistically significant difference was found,and the correlation was decreased with the time;Cm SAD and Cm FAD2 has no significant correlation.MDA has no significant correlation with fatty acids desaturases.(3)Test showed that under different high temperature treatment,the antioxidant enzyme activity response of chrysanthemum in different trend.In addition to SOD activity was not obvious change trend,POD activity,CAT activity and MDA content were significantly correlated with heat treatment temperature and time.POD activity shows different trend in leaf and root,the peak in root are 2.07 times than leaf.CAT activity increased with the rising temperature.MDA content was a positive correlation with the time and temperature.Under high temperature stress,chrysanthemum by adjusting the fatty acids desaturases gene expression,change the proportion of fatty acids,and adjusting the peroxidase activity to remove the excess reactive oxygen species,thus maintaining the stability of cell membrane,help the plants to cope with adversity.