**5. Conclusions**

Our results demonstrate that *A. deliciosa* 'Garmrok' kiwifruit can be stored at 0 ◦C for more than two months when preharvest chitosan was applied to kiwifruit. Preharvest application of chitosan reduced weight loss, maintained firmness by modulating the expression of ethylene biosynthesis, cell wall modification, and lignin metabolism-related genes, possibly evoked antioxidant activity by phenolic metabolism, and displayed a maturityand the ripening-delaying effect that improved the overall quality and extended the storage life of kiwifruit. This work also revealed that the treatment with 500 mg·L−<sup>1</sup> chitosan was more effective in maintaining overall physicochemical attributes of 'Garmrok' kiwifruit during postharvest storage. The results open a promising strategy for maintaining the postharvest properties of kiwifruit. Detailed mechanistic insights that underlie physicochemical attributes need to be further investigated. In addition, the possible effect on sensory attributes of chitosan-coated kiwifruit and lignin accumulation for the consumer's acceptance should be taken into consideration in future studies.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2304-815 8/10/2/373/s1, Table S1: Effects of preharvest chitosan application on sugars (fructose, glucose, and sucrose) and organic acids (oxalic, quinic, malic, and citric) (HPLC analysis) in 'Garmrok' kiwifruit during cold storage. Experimental data represent means ± standard error with n = 3. \*, in each column indicate significant differences between treatments at each sampling date, according to the least significant difference (LSD) test at *p* ≤ 0.05, Table S2: The primer sequences and gene information used in this study, Table S3: Ethylene production, respiration, fruit weight loss, flesh firmness and core firmness of 'Garmrok' kiwifruit as affected by chitosan-treatment and days of storage at 0 ◦C, Table S4: Soluble solids content (SSC), titratable acidity (TA), total sugar content (HPLC analysis), total acid content (HPLC analysis), and their ratios of 'Garmrok' kiwifruit as affected by chitosantreatment and days of storage at 0 ◦C, Table S5: Total phenolic content and total lignin content of 'Garmrok' kiwifruit as affected by chitosan-treatment and days of storage at 0 ◦C, Table S6: Relative expression of ethylene biosynthesis-related genes (*AdACS2* and *AdACO2*), cell wall-modification genes (*AdPGC*, *AdEXP1*, and *AdEXP2*), and lignin metabolism-related genes (*AcPAL*, *AcCAD*, and *AcPOD2*) of 'Garmrok' kiwifruit as affected by chitosan-treatment and days of storage at 0 ◦C.

**Author Contributions:** Conceptualization, J.G.K.; methodology, Y.-H.K.; formal analysis, H.M.P.C.K.; investigation, Y.-S.L.; resources, M.L. and Y.-B.K.; writing—original draft preparation, H.M.P.C.K.; writing—review and editing, J.K.; supervision, J.G.K. and J.K.; funding acquisition, J.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by research fund of Chungnam National University (J.K).

**Acknowledgments:** We acknowledge Seon-In Yeom (Gyeongsang National University, Republic of Korea) for providing access to their laboratories for conducting gene analysis studies and real-time qPCR studies. We thank Yang Jae Kyung and Ji Young Jung (Gyeongsang National University, Republic of Korea) for allowing conducting lignin analysis experiments at their laboratory. Also, we thank Seon-Gi Jeong (Gyeongsangnam-do Agricultural Research and Extension Services, Republic of Korea) for the help on the scanning electron microscope.

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