| Chinese flowering cabbage is one of the largest cultivated vegetables in Southern China,which is a vulnerable to cadmium pollution,cadmium accumulation ability of vegetable crops.With the aggravation of soil cadmium pollution,a serious problem has caused by Cd content exceed the standard.There is a great significance on reducing soil Cd content in the production process while cultivating Cd tolerance Chinese flowering cabbage varieties for the creation of green agriculture and modern agriculture.So,study of the molecular mechanism of Cd tolerance and identification of related genes will provide theoretical reference for pollution-free vegetable breeding.To increase our understanding of the adaption for Cd tolerance in Chinese flowering cabbage,’CX4’ and ’LB70’ were used as experimental materials in the present study.Determination of Cd resistant Chinese flowering cabbage cultivars and Cd sensitive cabbage varieties by physiological index analysis.The mechanism of Cd tolerance in Chinese flowering cabbage was investigated based on the information of expression profiles of related genes,and techniques such as transgenic technology.The function of Cd tolerance related gene was also analyzed.Discussion of the molecular and physiological mechanism of Cd tolerance in flowering Chinese Cabbage.The main results are as follows:(1)’CX4’ and ’LB70’ with-Cd and 50 Cd treatment,analysis of physiological phenotype of the seedlings,’LB70’ to Cd tolerance is stronger than ’CX4’.(2)Roots of Chinese flowering cabbage of ’LB70’ with-Cd and 50 Cd as materials to analysis the expression profiles.There are identified 3073 differentially expressed genes,1404 up-regulated and 1669 down regulated genes which differentially expressed genes.The results of GO analysis showed that these genes were mainly involved in binding,catalysis,metabolic process,cellular process,single-organism process,biological regulation,localization and response to stimulus.Pathway analysis showed that these differentially expressed genes were mainly involved in 48 pathways,which 22 pathways specially in Chinese flowering cabbage under Cd tolerance compared with other crops.The results show that these specific expression pathway may be related to the strong tolerance to Cd ability of Chinese flowering cabbage.(3)In the expression profiling results mentioned above,functional analysis of BpPMSR3(Bra005938)for subsequentgene study.The full-length sequence of BpPMSR3 CDS was amplified by PCR,which is 555 bp,encoding 184 amino acids belongs to a member of PMSR super family.And analysised the amino acid sequence of BpPMSR3 encoding,the physicochemical properties of the protein domains,functional domain prediction,homology sequence alignment and phylogenetic analysis;The expression pattern of BpPMSR3 was analysised by qRT-PCR,the results showed that when the Chinese flowering cabbage suffered Cd stress,expression of BpPMSR3 was up-regulated in ’LB70’(Cd resistant cabbage cultivars),nearly no difference in ’CX4’(Cd sensitive cabbage cultivars).The results show that BpPMSR3 may be regulated by the Cd tolerance of Chinese flowering cabbage.(4)Consruct over-expression vector 1250-3301::BpPMSR3,transformed into Columbia wild type Arabidopsis thaliana.The results show that,under 50 Cd treatments the wild-type root length was significantly reduced,1.65±0.1465 cm.However,there is no difference between transgenic plant and wild-type with-Cd,but under 50 Cd treatments,the transgenic plants root length was higher than that of the control,respectively.In addition,under 50 Cd treatments,the fresh weight of the wild type and the transgenic plants were reduced by 45.68%,30.81%,27.22%,and 26.14%,respectively,compared with untreatment plants.(5)Determination of MetSO with-Cd and 50 Cd treatment on wild type and transgenic Arabidopsis.There is no difference between transgenic plant and control uneder-Cd condition,while the content of MetSO of transgenic plant is lower than wild type.The content of Met and GSH in transgenic plants were significantly higher than those in wild type with 50 Cd.The results showed that the BpPMSR3 could increase the content of Met and GSH by decreasing the content of MetSO in plant,which could enhance the Cd tolerance to maintain the normal growth and development.In addition,the expression levels of AtHMA3,AtMAAN3 and AtNrampl in the transgenic plants under Cd stress were significantly higher than those in wild type.This indicates that the transgenic plants exhibit cadmium tolerance probably due to the cooperative work of the proteins encoded by these genes.These results indicated that overexpression of BpPMSR3 could enhance the Cd tolerance in Arabidopsis thaliana. |
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