Screening And Evaluation Of Low Cadmium Accumulation Ability Strains In Agaricus Blazei Murill

Agaricus blazei Murrill,also known as Brazilian mushroom,is an edible mushroom that originated in Brazil.Agaricus blazei Murrill has high nutritional value and medicinal value,and plays an important role in anti-tumor activity,anti-apoptotic effect and cardiovascular prevention.Studies have pointed out that Agaricus blazei Murrill mycelia has a strong ability to enrich heavy metal cadmium,and the cadmium content in the fruit body is high,which easily exceeds the edible standard,resulting in food safety problems related to Agaricus blazei Murrill.Therefore,to explore the physiological and molecular response mechanism of Agaricus blazei Murrill cadmium stress provides a theoretical basis for the research of Agaricus blazei Murrill heavy metal stress,which is of great significance for solving practical production problems.In this paper,different varieties of Agaricus blazei Murrill mycelium and fruit bodies were used as materials,and through cadmium stress treatment,high cadmium and low cadmium enriched varieties were screened out.The fresh weight,cadmium content and enrichment coefficient of Agaricus blazei Murrill mycelium were determined.Combined with the results of transcriptome sequencing,metabolic pathways and genes related to cadmium stress were analyzed,and the molecular regulation mechanism of Agaricus blazei Murrill in response to cadmium stress was explored.The research results of this paper are as follows:1?Identified 11 strains of Agaricus blazei Murrill with the antagonistic and ISSR molecular markers.The results show that the simple antagonistic test cannot distinguish all strains.Using ISSR molecular markers,the 11 strains tested were further divided into 11 varieties with a genetic coefficient between 0.418-0.919,of which J7 and J8 varieties had a genetic coefficient of 0.919,and the genetic background was very similar.In this article,J7 and J8 are considered to be two varieties with very similar genetic backgrounds.2?The J4 strain of 11 Agaricus blazei Murrill strains was selected as the test material.Growth rate and mycelium morphology.The results showed that with the increase of the concentration of cadmium solution,the growth rate of mycelium decreased and the growth became weaker.When the concentration of cadmium solution is 8 mg/L,mycelium germinates only at the inoculation point,and basically no longer grows.When the cadmium concentration gradient in the medium is 0 mg/L,1 mg/L,2 mg/L,3 mg/L,4 mg/L,5 mg/L,6mg/L,7 mg/L,8 mg/L,the growth of mycelium The speed is faster under the condition of cadmium concentration of 2 mg/L,and the mycelium is white and sturdy,so the concentration of the subsequent cadmium stress test is set at 2 mg/L.3?The liquid cultured mycelium and fruit bodies of the 11 tested strains of Agaricus blazei Murrill were placed in the control liquid and the liquid with a cadmium concentration of 2 mg/L for 15 days.By analyzing the dry weight,cadmium content and enrichment coefficient of mycelium,it was found that the cadmium content of the liquid cultured mycelium after cadmium treatment was higher than that of the control group,and at the same time,it was found that cadmium stress reduced the biomass of mycelium;The variety with the highest cadmium content was J11,and the variety with the lowest cadmium content was J4;by analyzing the agronomic characters and cadmium content of the fruit body after cadmium treatment,it was found that the cadmium content in the cap was about three times that in the stem.There was no significant difference between the yield of the control fruit body and the cadmium stress fruit body,but the cadmium content of the cadmium stress fruit body was much higher than that of the control fruit body.The highest cadmium content in the fruit body was J3,the lowest was J4,and the highest yield was J5.It was found that the cadmium enrichment of Agaricus blazei Murrill showed a difference between the liquid mycelium and the fruit body.4?The low cadmium enriched strain J4 and the high cadmium enriched strain J11 from the liquid mycelium of Agaricus blazei Murrill were treated with cadmium stress,and the processed materials and the control material(without exogenous cadmium addition)were subjected to transcriptome sequencing.In the low-enriched cadmium variety J4,a total of623 differential genes were detected in the cadmium stress sample J4 Cd and the control sample J4 CK,of which 244 genes were significantly up-regulated and 379 genes were significantly down-regulated.In the highly enriched cadmium variety J11,a total of 1386 differential genes were detected in the cadmium-stressed sample J11 Cd and the control sample J11 CK,of which 580 genes were significantly up-regulated and 806 genes were significantly down-regulated.The annotation results indicate that the differentially expressed genes are mainly concentrated in steroid biosynthesis,antibiotic biosynthesis,endoplasmic reticulum protein processing,glutathione metabolism and other pathways.Carbon metabolism and glutathione metabolism may play an important role in the response of Agaricus blazei Murrill mycelium to cadmium stress.Using real-time fluorescence quantification technology to verify some selected genes,and found to be consistent with the transcriptome data results,confirming the accuracy of differential gene expression.