| to study the factors affecting the cadmium enrichment ability of different varieties of potatoes in potato growing areas,the effects of soil cadmium migration ability on the cadmium enrichment ability of potatoes in potato growing areas could be understood,and the differences in the cadmium enrichment ability of different varieties could be preliminarily determined.According to the difference of enrichment ability among varieties,6 varieties(3 high enrichment varieties and 3 low absorption varieties)were selected for cadmium stress resistance test.To explore and identify the cadmium resistance ability of different varieties of potato during the barley growing period,and establish a mathematical evaluation model of the cadmium resistance.Meanwhile,transcriptome sequencing is used to further understand the molecular mechanism of the cadmium resistance of potato and dig candidate genes.It can not only lay a foundation for the evaluation of cadmium resistance and variety selection,but also provide a theoretical basis for the germplasm selection in the main potato area.The variation coefficient(1.24)of 90 potato varieties and the corresponding soil enrichment coefficient in the potato base indicated that the cadmium resistance of different potato varieties might be different.Thirty pairs(10 potato varieties X 3 soil planting types)of potatoes and corresponding soil were randomly selected as the experimental objects.The K-means clustering method(clustering index: p H,organic matter,CEC,total cadmium,effective cadmium)and F test were used to analyze the cadmium enrichment capacity of different potato varieties under different soil types.The results showed that the content of cadmium in potato tubers in producing areas was 0.030 ~ 0.146mg/kg,with an average value of0.086 mg/kg,and the correlation with total cadmium and effective cadmium was 0.631 and 0.775,respectively.Soil available cadmium is only positively correlated with total cadmium and p H,while organic matter and CEC weaken this correlation.From the correlation of total cadmium,effective cadmium and potato cadmium content in the producing area,the effective partition characterization of cadmium migration ability in the study area is more accurate.The difference of soil effective cadmium content is mainly influenced by total cadmium and soil physical and chemical properties.Sigp H & total cadmium =5.639e-0.5 in the region with higher total cadmium and lower p H,the effective cadmium was significantly higher,leading to enhanced cadmium enrichment capacity of potatoes.In addition,there were 5 kinds of clustered soils and 7 kinds of tubers with different cadmium contents.The content of weitu 5 was 0.061mg/kg in the soil with the lowest total cadmium and effective cadmium,high p H,organic matter and CEC(category ii),and 0.091mg/kg in the soil with medium total cadmium,effective cadmium,and p H,and high organic matter and CEC(category iii).Although the resistance of different varieties of potatoes varied in different soil types,among the 10 varieties,the enrichment ability of xuanyu no.2(a)was the strongest on the whole,while that of yunshu no.505(e)was the weakest.According to different enrichment coefficients and bioavailability of potatoes,6 varieties(qingshuai no.9,weitu no.7,yunshuai no.505,yunshuai no.801,bishuai no.2 and LZ sichuan)were selected for the pot experiment of cadmium resistance.Three treatments(CK),short-term cadmium stress(S)and long-term cadmium stress(L)were used to determine the agronomic characters,photosynthetic ability,leaf enzyme activity and other physiological and biochemical indexes of 6 potato varieties under different treatments,such as plant height,maximum node spacing,tillering number and so on.The resistance to cadmium of potato varieties was comprehensively evaluated by membership function method,principal component analysis and cluster analysis,and the optimal regression equation was established by stepwise regression analysis to predict and identify the resistance to cadmium of potato varieties.The results of difference analysis showed that cadmium stress had a significant effect on all indexes of potato,which was embodied in 18 physiological indexes,including aboveground index,chlorophyll a content,chlorophyll b content,total chlorophyll content,Fo,Fm and Fv/Fm.These indexes were converted into five independent comprehensive indexes by principal component analysis(the cumulative contribution rate reached 83.55%),and the first principal component mainly reflected the content of chlorophyll a,chlorophyll b,total chlorophyll,Fm and Fv/Fm,etc.The second principal component reflects the information of photosynthetic dark reaction such as ETR,qp and NPQ.The 3rd principal component reflects t-sod and CAT related information,the 4th principal component reflects MAD,the 5th principal component reflects POD and OPP enzyme activity.In order to predict the cadmium resistance of each genotype and establish a mathematical evaluation model,D value was used as the dependent variable,and the cadmium resistance coefficient of each index was used as the independent variable for stepwise regression analysis.Results show that the optimal regression equation,through the establishment of chlorophyll b selection,CAT,ETR this 3 items affecting the potato resistance to cadmium ability index,and six potato genotypes of seedling ability of resistance to cadmium predicted values and the D value significantly related adjustment(R2 = 0.940 **),shows that using this equation to forecast the potato resistance to cadmium characteristics has certain accuracy and high efficiency,can simplify the potato resistance to cadmium features of the appraisal work.According to the cluster analysis diagram,the tested varieties were divided into three types,namely,weiyu no.7 and yunshu 801 were cadmium resistant varieties.Yunshu 505,bishu 2 and LZ sichuan are intermediate varieties.Qingshu 9 is not resistant to cadmium.Leaf transcriptome sequencing of 3 cultivars with the strongest cadmium resistance was selected according to the clustering results.Plants respond to abiotic stress by regulating transcriptional regulatory centers through ABA and independent pathways.Illumina platform rna-seq was used to analyze 11 potato c DNA libraries treated with different cadmium concentrations at different times.A total of 3,458 and 3,422 up-regulated and down-regulated cadmium sensitive genes were identified by reference transcriptome analysis.The core groups of 31 genes and 49 genes were simultaneously up-regulated or down-regulated in all samples.In addition,Man Map analysis showed that,in the short-term stress group,different varieties led to inconsistent gene behavior.In the long-term stress group,the behavior of different genes among varieties was more consistent.Compared with the blank group,the difference genes of short-term stress mainly occurred in photosynthetic system,hormone system and REDOX system.The long-term stress group was involved in various plant systems.The genes involved in different treatment groups showed that the traits(photosynthetic rate and fluorescence parameters)decreased due to the changes of photosynthetic genes.Gene changes related to hormone system and REDOX system may be the response or the effect of cadmium stress.In addition,coexpression network analysis found 10 transcriptional regulation modules,30 transcriptional factor families related to cadmium stress and some candidate genes in leaves,which may be the main regulatory centers in leaves.These findings are helpful for further understanding the molecular mechanism of cadmium resistance in potatoes and improving potatoes. |
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