Alleviation of Cd toxicity and impedance of Cd transport in maize seedlings by the metal resistant-plant growth promoting bacterium Burkholderia sp.
A sand culture experiment was conducted to investigate how metal-resistant and plant growth-promoting bacterium alleviate Cd toxicity and reduce Cd transport in maize.Different concentrations of Cd were added to the nutrient solution to assess how inoculation with Cd resistant and plant growth promoting bacterium YM3(Burkholderia sp.)affect the dry weight,physiological indicators,Cd content,and metal transport gene expression in maize seedlings.The results showed that inoculation with the bacterial strain YM3 could promote maize growth.Moreover,this growth promoting effect was more pronounced under Cd stress,resulting in an increase in dry weight of maize roots,stems,and leaves by 9.09%-40.00%,63.33%-84.41%,and 48.50%-67.48%,respectively.Total chlorophyll content and root activity of maize increased by 1.70%-53.17%and 7.40%-16.93%,respectively,after inoculation.Free proline decreased by 3.04%-21.82%.At a Cd concentration of 12 mg·L-1,malondialdehyde content decreased by 26.37%.Inoculation of the YM3 strain significantly reduced the Cd content of the aboveground parts of maize,resulting in a reduction in Cd content of 13.64%-41.84%for stems and leaves and 17.85%-20.29%for leaves.q-PCR was used to detect the expression levels of metal transport related genes HMA2,HMA3,and Nramp5.The results showed that the YM3-regulated expression of heavy metal transport related genes was influenced by Cd concentration.In the inoculated 0 and 8 mg·L-1 Cd treatments,the expression levels of HMA2,HMA3,and Nramp5 in the roots were down regulated.In the inoculated 8 and 12 mg·L-1 Cd treatments,the expression levels of HMA2 and Nramp5 in the leaves were also down regulated.The inoculation treatment inhibited the absorption and transportation of Cd in maize seedlings by varying degrees,affecting the expression levels of the genes HMA2,HMA3 and Nramp5.In summary,inoculation with Cd resistant and plant growth promoting Burkholderia sp.strain YM3 under Cd stress can promote the growth of maize seedlings,alleviate Cd toxicity in maize seedlings,and prevent Cd transport from roots to aboveground parts,which has the potential to promote safe production of maize.
metal resistant and plant growth promoting bacteriamaizeCdtransport genephysiological trait
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