The Effect Of Exogenous NO And Ethylene On Quality And Ethylene Related Synthesis Genes Expression Of Postharvest Tomato

The effects of exogenous NO and ethylene treatment on "Shen Guanyou" tomato of different mature were studied. The parameters were analyzed that associated with quality, ethylene, ethylene related synthesis enzymes. The regulatory mechanism of ethylene related genes were further investigated by exogenous NO and ethylene treatment. The regulation of physiological effects of ethylene, as well as the possible signal transduction of exogenous NO and ethylene treatment of postharvest fruit were initially revealedThe main results indicated that:(1) NO treatment inhibited the decrease of firmness, delayed the increase of soluble solids and slowed down the color turning red. On the contrary, the result of exogenous ethylene treatment increased the rot of tomato fruit at green stage. NO and exogenous ethylene also delayed the decrease of quality of tomato fruit, however, NO separate treatment was better than NO and exogenous ethylene treatment to remain the quality of fruit. Results indicated that NO treatment was better to remain quality of fruit and to catalysis mature aging of fruit by exogenous ethylene. There was a antagonistic action between NO and exogenous ethylene to green stage tomato,NO treatment promoted the increase of firmness, but promoted the increase of soluble solids and the color to turn red of tomato fruit at pink stage. Exogenous ethylene treatment resulted in the quickly decreased firmness, soft rotten of fruit, and it’s the same result on soluble solids and the color of fruit with NO treatment. It is suggested that NO was negative on controlling the quality change of fruit at pink stage.(2) NO treatment induced the increase in the activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), APX activities of tomato at mature green and SOD activities of tomato at pink stage. NO treatment reduced MDA content, delayed the losing of soluble sugar of tomato fruits at mature green stage. However, there was no significant influence on the POD, CAT, APX activity and MDA content of tomato fruits at pink stage.(3) The decrease of ACC contents, ACS activity and ACO activity were found in tomato fruit fumigated with NO treatment inhibited ethylene production at pink stage. However, the result of exogenous ethylene treated fruit was reverse. NO and exogenous ethylene treatment induced ethylene production, ACC content, ACS activity, ACO activity of fruit more than only NO treatment, but less than only exogenous ethylene treatment. This phenomenon of antagonistic showed that it was delayed the mature aging and remain quality of tomato fruit at green stage.The peak of ethylene production, ACC content, ACS activity, ACO activity of fruit was appeared in advance, by NO treatment at pink stage. The ethylene production had more accumulation and induced ethylene and synthesis enzymes by exogenous ethylene treated at early stage of storage. However, NO treatment could not inhibited catalysis effect of exogenous ethylene treatment, so it promoted quickly the aging of fruit and intensified deterioration of fruit quality.(4) NO treatment significantly inhibited the increase of gene expression of LeACS2, LeACS4, LeACO1 and LeACO4, due to different activation period and expression level for every genes.The expression of LeACO1 had great more expression than other genes of tomato fruit at green stage, while exogenous ethylene induced a large expression of LeACS2, LeACS4, LeACO1 and LeACO4 genes. NO treated could control the result of large expression of this genes by exogenous ethylene, but the expression exceeded the only NO treatment. It was suggested that there were antagonistic action between NO and exogenous ethylene at the molecular level.Unless LeACS2 gene, NO treatment induced LeACS4, LeACSO2, LeACO4 genes expression of tomato during the pink stage of storage. However, exogenous ethylene promoted large expression of every gene at early stage of storage, and NO induced the effect of exogenous ethylene treated genes expression. NO and ethylene treatments could induce the increase of ethylene production and lead the ripening of fruit during storage.