| Botrytis cinerea is a kind of plant pathogenic fungi.Because of its wide host range and various pathogenic stages,it has caused huge economic losses to agricultural production.Therefore,it is of great significance to explore an economical and efficient fungicide specific to Botrytis cinerea.Previous studies found that GR24(synthetic analogs of strigolactone)could alleviate the pathogenicity of Botrytis cinerea,but the inhibitory effect and mechanism of GR24 on pathogenicity of Botrytis cinerea need to be further verified and clarified.Firstly,the pathogenicity of Botrytis cinerea to arabidopsis leaves,tomato leaves and rose petals was significantly reduced by adding GR24 at a concentration gradient of10-30 μM,and the pathogenicity of Botrytis cinerea to tomato leaves was almost completely lost by GR24 at 30 μM.Then,by observing the growth and development related indexes of Botrytis cinerea with different concentrations of GR24,it was found that GR24 could inhibit the growth and development of Botrytis cinerea.Therefore,GR24 may inhibit the pathogenicity of Botrytis cinerea by inhibiting its growth.To further clarify the molecular mechanism to GR24 inhibit the growth of Botrytis cinerea,after using high-throughput sequencing technologies to GR24 processing of Botrytis cinerea expression patterns were tested,and found that the REDOX and related amino acid metabolism activity is significantly enriched,and the most relevant to raise the level of gene expression,show GR24 was by inhibiting the two physiological activities and inhibited the growth of Botrytis cinerea.Furthermore,by measuring physiological indicators such as hydrogen peroxide and malondialdehyde before and after GR24 treatment with different concentrations of GR24,we found that ROS levels in Botrytis cinerea were positively correlated with GR24 concentration,indicating that ROS content is indeed one of the main targets of GR24.In addition,by adding different amino acids,it was found that cysteine could restore the inhibition of GR24 on the growth and development of Botrytis cinerea and its pathogenicity,indicating that cysteine metabolism is also one of the main targets of GR24 inhibiting the growth of Botrytis cinerea.The specific research results obtained are as follows:(1)After 30 μM GR24 treatment,the pathogenicity of Botrytis cinerea spores to Arabidopsis,tomato leaves and rose petals decreased significantly.First describe the results of the weakening of pathogenicity,and then describe the results of GR24 inhibiting the growth of Botrytis cinerea on the medium.At the same time,it was verified again that the mycelial radial growth,germ tube elongation and spore germination rate of Botrytis cinerea were significantly inhibited after exogenous application of high concentration GR24.In particular,with the gradual increase of GR24 concentration,the inhibitory effect on the growth and pathogenicity of Botrytis cinerea became more and more obvious.This shows that high concentration of GR24 has a stable inhibitory effect on the growth and pathogenicity of Botrytis cinerea.(2)By analyzing the transcriptome results,we obtained two main biological processes that may be involved in the response of Botrytis cinerea to high concentration GR24-redox reaction and amino acid metabolism.Further in vitro validation experiments are prepared for these two biological processes.(3)ROS levels in Botrytis cinerea were positively correlated with the concentration of exogenously added GR24,suggesting that REDOX activity was indeed one of the main targets of GR24.RT-PCR results showed that the expression levels of REDOX Bc OPR1/2/3/4/5 genes were significantly increased after 30 μM GR24 treatment.DAB staining showed that with the increase of GR24 concentration,the level of hydrogen peroxide in Botrytis cinerea also increased.Through the determination of malondialdehyde(MDA)content,it was found that GR24 could increase the peroxidation level of cell membrane of Botrytis cinerea,resulting in a large amount of extracellular MDA accumulation.(4)In addition,cysteine metabolism is also one of the main targets of GR24 inhibiting the growth of Botrytis cinerea.It was found that cysteine could relieve the inhibition of GR24 on mycelial growth,spore germination and bud tube elongation of Botrytis cinerea by exogenous application of 17 common amino acids,and restore the virulence of Botrytis cinerea to plants.In conclusion,it was found that GR24 had an inhibitory effect on the growth and development of Botrytis cinerea and also inhibited its pathogenicity.Further exploration revealed that ros generation and cysteine synthesis are key targets in this inhibitory pathway.The results of this study showed that GR24 had the potential to be a new bacteriostatic agent for Botrytis cinerea,which laid a theoretical foundation for the future study of its bacteriostatic mechanism.Based on this,it is expected to design a safer,cheaper and specific green antibacterial agent for Botrytis cinerea. |
