| In order to explore the tolerance of heavy metal cadmium to the cadmium content and germination stage of rice grain,cadmium-resistant materials were screened,cadmium uptake in seeds of sub-rice seeds was explored,and low-cadmium accumulation genes and cadmium-tolerant genes of rice were explored.In this study,9311 was used as the recipient parent and the Nipponbare donor parent to construct a chromosome fragment replacement line containing 119 chromosomes,and 5μmol/L heavy metal was subjected to cadmium stress treatment at the budding stage,cadmium-related QTLs were localized,and cadmium content and cadmium stress at budding stage were analyzed in rice grain by combining RNAseq to analyze candidate genes related to cadmium content and cadmium stress at the budding stage.The main results are as follows:(1)The principal component analysis method and membership function method were used to comprehensively evaluate the cadmium stress index of rice budding stage 7 days after the end of stress treatment,and 6 very strong cadmium-resistant materials,68 strong cadmium-resistant materials,28 medium cadmium-resistant materials and 16 weak cadmium-resistant materials were screened.The higher the weight,the more suitable for planting environment was identified for the analysis of germplasm material with extreme cadmium accumulation,and the higher the cadmium tolerance ability,the more suitable for planting in a mild-cadmium polluted environment.(2)The displacement line population was used as experimental material and subjected to cadmium stress treatment of 7d 5μmol/L.A total of 14 QTLs(LOD≥2.0)associated with cadmium tolerance in rice were detected in two environmental harvesting stress QTLs in Hainan and Nanchang,and a total of 14 markers were detected on chromosomes 3,4,5,6,7 and 11,2 markers on chromosome 3,5 markers on chromosome 4,2 markers on chromosome 5,2 markers on chromosome 6,2 markers on chromosome 7,and 1 marker on chromosome 11.q TRL7.1 was repeatedly detected near the bin378 marker on chromosome7 and was the dominant QTL.This suggests that these QTLs are most likely related to cadmium tolerance in rice.(3)Two parents,9311 and Nipponbare who were treated under 5μmol/L cadmium stress for 7 days,were selected for transcriptome analysis,and a total of 5256 differentially expressed genes were found,including 2776 genes up-regulated and 2480 down-regulated genes.The enrichment analysis in the GO group found that it may be related to cadmium stress in rice budding,which may involve "cysteine metabolism","glutathione metabolism","photosynthesis" and other pathways.Candidate genes were screened LOC＿Os0501675,LOC＿Os02530,LOC＿Os0644750,LOC＿Os0735004,LOC＿Os0735260,LOC＿Os0735370,LOC＿Os35140,LOC＿Os0502530,LOC＿Os0502070,LOC＿Os0500410,LOC＿Os0504450,LOC＿OS0637080,LOC＿Os0735390,LOC＿Os0432620 may regulate the photosystem IP700 chlorophyll A,cysteine receptor-like protein kinase,glutathione-S-transferase,serine/threonine kinase,ethylene and other functions.(4)The membership function method was used to cluster and analyze the cadmium accumulation of rice grain under natural cadmium pollution,and 9 strong cadmium-resistant materials,5 medium cadmium-resistant materials and 102 weak cadmium-resistant materials were screened.Based on the screening materials,the QTL localization of rice grain cadmium content under natural conditions under natural conditions was analyzed.A total of 6 QTLs(LOD≥2.0)were detected,which were distributed on rice chromosomes 3,4 and 6,with 2markers on each chromosome.The germ growth resistance index and the cadmium content of rice grain under natural conditions after environmental harvesting stress in Hainan were analyzed and were repeatedly detected in q TRL3.1 and q TRL3.2 near the bin147 and bin190 markers on chromosome 3,q TRL4.1 and q TRL4.5 near the bin192 marker on chromosome4,and q TRL6.1 near the bin323 marker on chromosome 6.This indicates that these QTLs are dominant QTLs,indicating that these QTLs are likely to be related to the accumulation of cadmium content in rice grains,which may be the same mechanism as cadmium stress response at the germination stage of rice. |
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