| Fusarium spp could cause fungal diseases of asparagus and result in huge economic losses of asparagus industry.However,there are few reports on the postharvest fungal diseases of asparagus and the control of the postharvest diseases.In this paper,the effect of Fusarium proliferatum FP2,which was isolated and purified by our own lab,on the quality of postharvest asparagus was investigated.Furthermore,the influence of F.proliferatum FP2 infection on the physiological metabolism of harvested asparagus was explored through analyzing the changes of respiratory metabolism enzyme activity and metabolite content of harvested asparagus.Then,the material metabolism related to disease resistance of postharvest asparagus was also analyzed,which can provide a new idea for controlling the fungus diseases of postharvest asparagus and a theoretical basis for breeding resistant asparagus varieties.The results of this study were as follows:(1)A pathogenic strain FP2 was isolated from rotten asparagus,and identified as F.proliferatum through molecular biology assay and morphological properties.FP2 had the pathogenicity when it was inoculated to fresh asparagus.And the strain FP3 isolated from the inoculated asparagus was also identified as F.proliferatum,which proved that FP2 was a pathogen of postharvest asparagus by Koch's Postulates.(2)F.proliferatum FP2 was inoculated on asparagus to investigate the effect of the pathogen on the quality of asparagus.The results showed that the content of soluble sugar and organic acid in F.proliferatum FP2 treated group was increased significantly in the early stage of infection compared with that of the control group.As the infection progresses,the content of soluble sugar and organic acid decreased significantly.While,the soluble protein content of F.proliferatum FP2 treated group was lower than that of control group in the whole storage stage.(3)The effects of F.proliferatum FP2 infection on the respiratory metabolism of asparagus were studied by measuring the activity of enzymes related to respiratory metabolism.The results showed that in the early stage of infection,the activitiy of pyruvate kinase(PK)and fructose-6-phosphate kinase(PFK)in the glycolysis pathway(EMP),succinate dehydrogenase(SDH),?-ketoglutarate dehydrogenase(?-KGDH),citrate synthetase(CS)and isocitrate dehydrogenase(ICDHm)in the tricarboxylic acid cycle(TCA),6-phosphogluconate dehydrogenase(6-PGDH)and glucose-6-phosphate dehydrogenase(G-6PDH)in the pentose phosphate pathway(PPP)in F.proliferatum FP2 treated group was increased significantly compared with that of the control group.But as the infection progresses,the activity of these enzymes in F.proliferatum FP2 treated group decreased gradually and was significantly lower than that of the control group.There was no significant change in the activity of ascorbic acid oxidase(AAO)during the whole storage period.(4)The effects of F.proliferatum FP2 infection on the accumulation of metabolites of asparagus were analyzed by metabolome and bioinformatics,and then the effects of the pathogen infection on the physiological metabolism of postharvest asparagus and the material metabolism related to disease resistant response of asparagus were explored.The results showed that the metabolic processes related to differential metabolites were mainly included glucose metabolism(EMP,TCA and PPP),linoleic acid metabolism,pyrimidine metabolism,amino acid metabolism and secondary metabolite synthesis.The physiological metabolism of asparagus was affected by the infection of F.proliferatum FP2 through the influence of infection on the above metabolic processes.The material metabolism basis of asparagus disease resistant response mainly included the accumulation of related resistant substances through the regulation of amino acid metabolism and the accumulation of terpenoids,phenols and alkaloids through the regulation of secondary metabolism. |
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