Co-expression networks provide insights into molecular mechanisms of postharvest temperature modulation of apple fruit to reduce superficial scald

Authors: Honaas, Loren; Hargarten, Heidi; FICKLIN, STEPHEN - Washington State University; HADISH, JOHN - Washington State University; WAFULA, ERIC - Pennsylvania State University; DEPAMPHILIS, CLAUDE - Pennsylvania State University; Mattheis, James; Rudell, David

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2018
Publication Date: 3/1/2019
Citation: Honaas, L.A., Hargarten, H.L., Ficklin, S., Hadish, J., Wafula, E., dePamphilis, C., Mattheis, J.P., Rudell Jr, D.R. 2019. Co-expression networks provide insights into molecular mechanisms of postharvest temperature modulation of apple fruit to reduce superficial scald. Postharvest Biology and Technology. 149:27-41. https://doi.org/10.1016/j.postharvbio.2018.09.016.
DOI: https://doi.org/10.1016/j.postharvbio.2018.09.016

Interpretive Summary: There are many known treatments that can influence apple fruit quality, but exactly how apple fruit respond on a molecular level to these treatments is mostly unknown. By knowing the molecular responses, we can learn exactly how postharvest treatments work, allowing us to improve them. Once we learn enough, we might be able to use this knowledge to predict fruit quality changes during storage. This paper reports experiments to examine molecular responses of apple fruit to a proven postharvest treatment - variations in temperature during storage. We discovered molecular responses that were correlated with the periods of warming. This information helps us understand what happens inside fruit during this effective treatment. This includes how fruit (which is alive during storage and when eaten) sense changes and how they respond.

Technical Abstract: Temperature conditioning is an effective approach for enhancing some aspects of postharvest apple fruit quality, particularly avoidance of chilling injury. The molecular mechanisms of warming regimes that alter apple fruit quality are poorly understood, as is how warming contributes to avoiding development of the peel disorder superficial scald. Here we report transcriptional responses of ‘Granny Smith’ fruit peel during the early phases of long term cold storage in response to intermittent warming, an ostensibly organic compliant strategy that effectively reduced scald incidence. We observed two temporally distinct classes of gene expression, which were discovered with high granularity gene expression clustering and co-expression network analyses. One profile is largely concordant with recovery from chilling stress, whereas the other reveals transient shifts marked by hormone signaling and transcription and translation machinery. Altogether, our analyses point to novel aspects of superficial scald etiology and circumscribes a list of candidate genes that may be useful to uncover molecular processes that promote, as well as mitigate, the peel disorder.