1a. Objectives (from AD-416):
Postharvest harvest CO2 injury is a recurring physiological disorder in many apple cultivars. Available evidences suggest that the condition of pre-harvest factors and postharvest regime can contribute to the development of this disorder. To gain the insight of how environmental and genetic factors influence the occurrence of this economically important postharvest disorder, transcriptome changes will be characterized to identify the aberrant gene expression under different pre-and postharvest conditions. Through the identification of potential genes and pathways inciting this disorder, the goal is to develop better prediction and prevention tools and management strategy.
1b. Approach (from AD-416):
Whole transcriptome sequencing method will be utilized to identify the global gene expression patterns on samples with various maturity and duration of postharvest storage and regimes. “Golden Delicious”, which is prone to the development of CO2 injury, will be used as model. Fruits from two different orchards at different location will be sampled from pre- and post-harvest stages, at different storage regimes for transcriptome analysis. Two orchards, one was previously classified with high tendency of CO2 injury incidence, will be selected for sampling. The detail of horticultural practice in two orchards such as application of chemical and/or nutrients application as well as microclimate parameter will also be taken into account when data are analyzed. Documents Trust with Agrofresh. Log 43619.
3. Progress Report:
This project relates to objective 1 of the associated in-house project which seeks to identify factors that influence postharvest fruit quality and development of market limiting physiological disorders. Postharvest CO2 injury is a recurring physiological disorder which can cause significant economic loss for some apple cultivars. The molecular changes associated with apple CO2 injury incidence are not known. To understand the genetic controls of this postharvest disorder, an integrated approach of physiology, transcriptomics, metabolomics and genetic survey has been employed. 1. Physiological characterization of preharvest fruit development and postharvest storage regimes related to CO2 injury incidence demonstrated contrasting season-to-season variations in severity. As fruit used for the experiment were from the same orchard, results indicate the seasonal variation in the fruit on-tree maturation process may significantly impact the propensity of CO2 injury incidence. 2. CO2 injury phenotypes for more 60 apple cultivars and/or breeding selections for susceptibility to CO2 injury indicate substantial variation in CO2 suseptability. 3. Transcriptome sequencing indicates transcriptomic changes related to phytosterol metabolism, oxidation/reduction imbalance and phytohormone signaling represent the major molecular changes in apple fruit under high CO2 pressure. 4. Metabolomic analysis indicates multiple metabolic pathways are activated in response to a high CO2 storage environment which may lead to injury in susceptible fruit.