Production Pattern And Molecular Regulatory Mechanism Of Fumonisins Contamination By Mycotoxigenic Fusarium Isolated From Greenhouse Pepper In China

Greenhouse peppers are highly specialized and economically important agricultural products in China,which also contributes to more and more in the whole dietary consumption.Till now,limited research on the production pattern and molecular regulatory mechanism of mycotoxins contamination in greenhouse peppers are carried out,which leads to serious issues regarding food safety and related industry development.Fumonisins are mycotoxins that are produced by Fusarium spp.Fumonisins reduce the productivity of crops and also cause adverse effects on human and animal health by damaging immune system and interrupting sphingolipid metabolism.Fumonisin contamination is common for greenhouse pepper in China and also other countries.In order to unveil the production pattern of fumonisins and their contamination in greenhouse pepper in China,the Fusarium isolates were first isolated and identified from the 34 different cities in China.The main pathogenic Fusarium species were then determined,and fumonisin production patterns by different pathogenic Fusarium were studied.Lastly,the molecular mechanisms of fumonisin-producing Fusarium solani were explored.Firstly,900 decomposed or healthy greenhouse pepper samples were collected from 34 different cities in China.277 isolates were first collected and mono-spore purified from diseased and healthy sites of peppers,and then the morphological and molecular characterization means were both conducted to identify the fusarium at the species level.Morphological identification were performed mainly through the observation of colony morphology,growth rate,color,size,and combination of the morphology of hyphae,the presence or absence of spores and other characteristics of the genus identification.Molecular identification was done by using fungal universal primers Internal Transscribed(ITS)and Fusarium specific primers Elongation factor 1-alpha(EF-1α)sequence of strain amplification.PCR results after sequencing the NCBI nucleic acid database were analyzed by BLAST.The experimental results have indicated that the 45 isolates of fusarium identified mainly include F.equiseti,F.F.equiseti is the dominant strain.Secondly,the time effect on Fusarium fumonisin production and the pattern of fumonisins production by Fusarium in different biological media were explored.F.equiseti,F.proliferatum,F.fujikuroi,F.verticillioides,F.oxysporum,F.solani which were isolated from China greenhouse pepper were inoculated onto the rice culture medium(25 ℃,dark)and were tested for fumonisin determination at 7d,14 d,21d,28 d and35d.The results demonstated that the content of fumonisins reached maximum level at 28 d for F.proliferatum,F.fujikuroi,F.verticillioides and F.oxysporum and at 21 day for F.solani.The fumonisins-producing levels of the same strain under the various culture conditions were significantly different and the fumonisins-producing levels between different Fusarium species under the same culture condition were obviously different as well.The results showed that F.solani can produce fumonisins on both rice medium or greenhouse pepper,which has not been reported in China and abroad.Finally,the molecular mechanism of fumonisin production by F.solani was studied.In the experiment,highly fumonisin-producing F.verticillioides was selected as the positive control and F.equiseti which does not produce fumonisins was chosen as the negative control.By using specific primers of FUM1,FUM8 and FUM19,Fusarium solani were amplified by polymerase chain reaction(PCR).High throughput sequencing was carried out and the results were analyzed,showing that there was no FUM gene in F.solani.