Klein, Simone Maria: Ripening-delaying peptides and their applicability to steer quality development of climacteric fruits. - Bonn, 2020. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-58729
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-58729,
author = {{Simone Maria Klein}},
title = {Ripening-delaying peptides and their applicability to steer quality development of climacteric fruits},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2020,
month = jun,

note = {Processes extending the shelf-life of climacteric fruits play an important role in increasing sustainability of global food supply. As consequence of uncontrolled ripening process, significant losses in quantity and quality exist at farm level and along the food chain. Ethylene is the key phytohormone triggering fruit ripening and senescence. Recent studies on the ethylene signalling pathway have shown that the signal transduction depends essentially on the interaction of the ethylene receptor (ETR) with the signal protein EIN2 (ethylene-insensitive protein 2). A novel synthetic octapeptide (NOP-1) derived from the so-called nuclear localization signal (NLS) at the C-terminal end of EIN2 inhibits the interaction between ETR and EIN2 and may slow-down fruit ripening. The main objectives of this study were to examine the ripening delay, and the mode-of-action, of the recombinant NOP-1 on tomatoes and apples. For this purpose, NOP-1 was applied as aqueous peptide solution onto the fruits´ surfaces after their harvest. Three different experiments, each one with a specific focus and its own particularities, were conducted.
Dose-response and response-time experiments were done by application of solution droplets to the surfaces of green tomatoes. Further, the effect of NOP-1 was examined on apple fruits, which produce several times more ethylene than tomatoes. In addition, the potential effect of different application methods was studied. Finally, a ripening-stage dependent effect of NOP-1, and the impact of repeated applications, were analyzed. In order to enable a time-resolved monitoring of fruit ripening, sensor-based evaluations were performed for quality assessments and compared to classic destructive quality determinations. In summary, the following results were obtained:
1. NOP-1 concentration of 1000 μMol delayed ripening of tomatoes for several days, when applied at maturity stage ‘mature green’, whereas concentrations of 400 μMol and 2000 μMol were not effective. Colour development, chlorophyll degradation and accumulation of lycopene and ß- carotene were inhibited whereas firmness was not affected. Likewise, no quality impairment was observed.
2. On apples, NOP-1 (1000 μMol) inhibited colour development and chlorophyll degradation during shelf-life. These effects were more pronounced with the brush application (surface film) than with the application of microdroplets (mimicking a spray formulation). NOP-1 did not alter ethylene release or respiration rate, whereas 1-MCP strongly suppressed both. NOP-1 shows no differences in the quality parameters firmness, titratable acidity (TA), total soluble solids (TSS) and starch index.
3. NOP-1 delayed ripening of tomatoes when applied at the maturity stage ‘breakers’ indicated by slower colour development. Repeated application had no additional delaying effect and did not reach the level of ripening delay induced by 1-MCP. When applied at the maturity stage ‘pink’ no ripening delay was observed. These results indicate that NOP-1 works best when applied at early ripening stages, long before autocatalytic ethylene synthesis takes place.
In general terms, our results show that NOP-1 has promising potential to delay fruit ripening and steer quality of climacteric fruits. Besides significant advances in understanding the technology and the mode-of-action, many details have to be better understood and adapted. In practical terms, more precise information is needed in terms of timing and frequency of application for different species and varieties, and the impact of NOP-1 on the different quality attributes of fruits.},

url = {http://hdl.handle.net/20.500.11811/8422}

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