A relação entre 1-metilciclopropeno e o progresso da podridão “olho-de-boi” (Neofabraea brasiliensis) em maçãs ‘MaxiGala’.

Abstract

With the use of refrigeration technologies, controlled atmosphere (CA) and the use of 1-methylcyclopropene (1-MCP), the period of conservation of apples was extended, for about 12 months. Even so, the occurrence of post-harvest pathogenic disorders is still limiting. In this case, it has been increasingly frequent the incidence of bull’s eye rot (Neofabraea ssp.). Data generated by the productive chain of the apple point to losses of 6 to 8% of the fruits during the post-harvest, due to this disease. In addition, there is an empirical perception that the incidence of rot is higher in fruits treated with 1-MCP treatment. In order to understand if 1-MCP is a facilitating factor for the occurrence of bull's-eye rot, 'MaxiGala' apples were studied, with and without 1-MCP, in two harvest per crop, and inoculated or not with the fungus N. brasiliensis. Besides, two situations were investigated: 1-MCP was applied to apples before and after inoculation. It was evaluated, after 90 days under CA, lesion diameter, percentage of rotten fruits, pulp softening, soluble solids content, titratable acidity, and the accumulation of transcripts of the genes MdACO, MdPG, MdPGIP, MdPPO, MdPAL e Mdthau. It was observed that apples treated with 1-MCP prior to inoculation had lower lesion diameter when compared to apples with 1-MCP after addition of the fungus. On the other hand, these presented lower % of rotten fruit, when compared to apples treated before inoculation. 1-MCP had an isolate effect only on the diameter of the lesion, in which apples treated with 1-MCP after inoculation with the fungus showed, on average, 1 mm of lesion diameter higher than apples without 1- MCP treatment. On the percentage of rotten, intrinsic factors (harvest and harvesting point) were the most prominent effects, not 1-MCP. Harvest 2017 and 1st harvest contributed to the lowest % of rotten (<44%). The apples with higher pulp softening were those that had a greater accumulation of transcripts of MdACO, MdPG, MdPGIP. The highest accumulation of MdPPO and MdPAL transcripts had a significant correlation with the bull's-eye rot while Mdthau not. For this last transcript, probably an effector triggered prior to storage was responsible for an higher transcript accumlations. Overall, the results indicated that the global responses were due to intrinsic variables, not 1-MCP. With the results obtained it is evidenced that 1- MCP cannot be attributed to the higher susceptibility of apples to infection of N. brasiliensis. In addition, because the factors harvest and harvest point were the most relevant, this indicates that, in order to arrive at a more robust technological conclusion, the experiments should be conducted for more harvests.