Effects Of Cadmium On Physiology,Biochemistry And Metabonomics Of Different Rice Varieties

Cadmium(Cd)is a heavy metal element with strong toxicity to animals and plants.Cd pollution will have a great impact on the growth and development of plants,and it is also an important factor restricting the productivity of global food crops.Therefore,it is very important to study the mechanism of Cd pollution on crops and select Cd tolerant rice varieties to improve the quality and yield of food crops.In this experiment,18 different rice varieties(lines)reserved by Tianjin Agricultural University were selected.Firstly,traditional physiological and biochemical detection methods were used to screen out rice varieties with different Cd tolerance.Secondly,gas chromatographymass spectrometry(GC-MS)was used to qualitatively and quantitatively analyze the small molecular metabolites of different varieties.Finally,principal component analysis and orthogonal partial least squares discriminant analysis were used.The results showed that:1.The results showed that: the stem length,stem diameter and root length of all rice varieties increased after Cd treatment;the content of superoxide dismutase(SOD)and catalase(CAT)increased in half of the rice varieties,among which Longyou 619 increased most significantly,while the SOD of Jinyuan 89 and cat of Jindao 777 decreased most significantly(P < 0.05);the content of superoxide dismutase(SOD)and catalase(CAT)increased in half of the rice varieties,The results showed that 6 rice varieties decreased,Jinyuan E28 decreased the most obviously,12 rice varieties increased,and jinyuanhei 1 increased the most;in soluble protein,61% of rice varieties increased,Longyou 619 increased the most significantly;the content of other rice varieties decreased;in MDA,the content of most rice varieties increased,and Jinchuan1 increased the most significantly,with only 3 rice varieties In proline(Pro),the activity of all rice varieties increased,contrary to malondialdehyde,the most significant increase was in agricultural college line 2.The sensitivity of antioxidant enzymes ranked as SOD > POD > CAT.2.The Cd tolerance index of rice seedlings was calculated,and the results showed that Jindao 179 and Longyou 619 had higher Cd tolerance than Jinchuan 1 and Jindao777.The overall trend of mineral element content in rice seedlings was K > Na > Mg >Ca > Fe > Mn > Zn > Cu.After Cd stress,the content of Cu increased as a whole,while the content of Mn and K decreased.Mg was similar to Ca,Fe and Zn,and Zn was positively correlated with Cu,Mg and Ca(P < 0.01).3.According to the above analysis results,18 rice varieties can be divided into two categories: the first category is common rice varieties: Jinyuan E28,Jinchuan 1,Jinyuan89,Jinyuan 45,Jindao 777,Jindao 919,c418 restorer line,agricultural college line 1and agricultural college line 4;the second category is Cd tolerant rice varieties,including jinyuanhei 1,jinyuanxiang 98,Jindao 179,Longyou 619,tiannongjing 518 and C34 Huifuxi.The results showed that there were three kinds of strains: multiple department,agricultural college strain 2,agricultural college strain 3 and agricultural college strain 5.Among them,Jindao 179 and Longyou 619 had higher Cd tolerance and could be planted in the soil containing about 0.5mg/kg Cd.Jinchuan 1 and Jindao777 had poor Cd tolerance and were not recommended to be planted in the soil polluted by Cd.4.After GC-MS analysis of rice,the total content of small molecule metabolites was organic acid > compound > sugar and derivative > amino acid > polyol.Three principal components were extracted by principal component analysis(PCA),all of which were highly correlated with organic acids,and the main metabolites were organic acids.Two differential metabolic pathways were screened out for Cd tolerance in rice,which were related to organic acids,while three were related to Cd stress,which were primary metabolites of organic acids and sugars.It can be seen that organic acids and sugars were the main differences in small molecule metabolites of rice under Cd stress.5.Cd tolerant rice varieties and common rice varieties after 0.5mg/kg After Cd stress,the growth of root length,stem diameter and stem length was promoted;SOD,CAT and soluble protein of Cd tolerant rice varieties increased,while SOD,CAT and soluble protein of common rice varieties decreased;in POD,Cd tolerant rice varieties generally increased,while common rice varieties as a whole decreased;in MDA,except for a few rice varieties with high Cd tolerance,SOD,CAT and soluble protein of common rice varieties decreased.All the other rice varieties showed an increase,and the greater the increase,the lower the Cd tolerance;all rice varieties showed an increase,but the increase of Cd tolerant rice varieties was greater than ordinary rice varieties.At the level of small molecule metabolites,the differences of Cd tolerance and Cd stress in rice were mainly organic acids,and the differences of different metabolic pathways were mainly organic acids.