Study On Stress Resistance Of Three Cross Rape At Seedling Stage Under Different Growth Environments

New hybrid rapeseed varieties have been widely used due to their full grain,high yield and good resistance.In recent years,new methods for tri-cross breeding have emerged,but there are few studies on its related field traits and physicochemical properties.In this study,the differences of growth traits,physiological and biochemical characteristics,and the expression levels of photosynthesis-related genes and heavy metal resistance-related genes between three-line rape(Fengyou 520 ×159-6)and their parents(Fengyou 520and159-6)were analyzed under different growth environments.The main results were as follows :1.it was found that the rhizome diameter,SOD and CAT activities of tri-cross rapeseed at bud and bolting stage were higher than those of parents,which were48.2 %,17.9 % and 66.4 % higher than those of hybrid parents,51.8 %,34.9 % and34.3 % higher than those of inbred parents,and 71.9 % higher than those of inbred parents,respectively.MDA content was 29.6 % lower than that of inbred lines;The soluble sugar content of three cross rape was between parents,which was 10.7%higher than that of hybrid parents(p < 0.05).The above differences were significant(P < 0.05).The results showed that the plants of three-cross rape were coarser than their parents at the bud stage and grew well.2.The chlorophyll content of three cross rape under different degrees of waterlogging and drought stress was higher than that of the control,and was significantly higher than that of its parents(P < 0.05).The dry weight of triple cross rape under mild waterlogging and severe drought stress was 80% and 20% higher than that of hybrid parents,200% and 100% higher than that of inbred parents,respectively(P < 0.001).The SOD activity under mild waterlogging and moderate drought stress was 44.8% and 62.1% higher than that of hybrid parents,179.9% and48.7% higher than that of inbred parents,respectively(P < 0.001).Under moderate and severe drought stress,POD activity was 64.1% and 22.6% higher than that of hybrid parents,154.2% and 91.1% higher than that of inbred parents,respectively(P< 0.001).3.3.The fresh weight and dry weight of three crossing rape in the environment with cadmium concentration of 0.75mg/kg were 54.1% and 53.3% higher than those of hybrid parents,20.4% and 15.7% higher than those of inbred parents,respectively;When cadmium concentration was 1.5mg/kg,the fresh weight and dry weight were32.0% and 53.3% higher than hybrid parents,16.2% and 14.9% higher than inbred parents,respectively;All reached a very significant level(P < 0.001).The POD activity in the environment with cadmium concentration of 0.75mg/kg was 25.7% and29.3% higher than that of hybrid parents and inbred parents,respectively;Except for the environment with cadmium concentration of 1.5mg/kg,the MDA content of three cross rape was significantly lower than that of their parents(P < 0.05).Three photosynthetic genes(bna049040,bna0280620 and bnac08g46180d)and four heavy metal resistance genes(bnaa08g0400d,bnaa09g24330 d,bnnramp1 and bnpri-mir167a)were studied.Among them,the expression of bna0280620 gene decreased first and then increased in the leaves of the three materials with the increase of cadmium concentration,and the expression of bna0280620 gene in the leaves of three cross rape under the environment of cadmium concentration of 1.125mg/kg and1.5mg/kg was significantly higher than that of their parents(P < 0.05).The gene expression of bnaa08g0400 d and bnaa09g24330 d decreased first,then increased and then decreased in the leaves of the three materials with the increase of cadmium concentration;The gene expressions of bnnramp1 and bnpri-mir167 a were the highest in the leaves of three cross rape under the environment of cadmium concentration of1.125mg/kg.Under the environment of cadmium concentration of 0.75mg/kg and1.125mg/kg,the expression of four heavy metal resistance related genes in the leaves of three cross rape was higher than that of their parents(P < 0.001).This study found that three cross rape grew better than its parents at seedling stage,had better stress resistance;and had better adaptability under waterlogging,drought and heavy metal stress.