**4. Conclusions**

The finding that pathogens isolated from all the climacteric fruits showed reduced growth when exposed to a low level of ethylene was quite unexpected. It suggests that pathogens colonising climacteric fruits derive some advantage by delaying growth early in the ripening sequence, possibly related to enhanced loss of cellular integrity arising from increasing ethylene action on fruit tissues. The lack of an effect of ethylene on pathogens from non-climacteric fruit could reflect the lack of enhanced ethylene synthesis during the ripening of such fruits and thus there is no advantage in an adaptive response to ethylene.

**Author Contributions:** P.P. carried out the experiments and analysed the data, R.B.H.W. conceived the research hypothesis that led to the experiments, contributed to the experimental design and wrote the manuscript draft, L.T. identified the fungal organisms and provided the pathology laboratory, J.B.G. organised the conduct of the experiments and contributed to the experimental design. All authors reviewed the draft manuscript.

**Funding:** This project received no external funding, but P.P. was supported by the Australian Research Council Training Centre for Food and Beverage Supply Chain Optimisation (IC 140100032) and J.B.G. was supported by the Hort Innovation Australian Citrus Postharvest Science Program (CT 15010).

**Conflicts of Interest:** The authors declare no conflict of interest.
