Network Analysis of Postharvest Senescence Process in Citrus Fruits Revealed by Transcriptomic and Metabolomic Profiling

Abstract

Citrus (Citrus spp.), a nonclimacteric fruit, is one of the most important fruit crops in global fruit industry. However, the biological behavior of citrus fruit ripening and postharvest senescence remains unclear. To better understand the senescence process of citrus fruit, we analyzed data sets from commercial microarrays, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry and validated physiological quality detection of four main varieties in the genus Citrus. Network-based approaches of data mining and modeling were used to investigate complex molecular processes in citrus. The Citrus Metabolic Pathway Network and correlation networks were constructed to explore the modules and relationships of the functional genes/metabolites. We found that the different flesh-rind transport of nutrients and water due to the anatomic structural differences among citrus varieties might be an important factor that influences fruit senescence behavior. We then modeled and verified the citrus senescence process. As fruit rind is exposed directly to the environment, which results in energy expenditure in response to biotic and abiotic stresses, nutrients are exported from flesh to rind to maintain the activity of the whole fruit. The depletion of internal substances causes abiotic stresses, which further induces phytohormone reactions, transcription factor regulation, and a series of physiological and biochemical reactions.

Inhibiting ethylene perception with 1-methylcyclopropene triggers molecular responses aimed to cope with cell toxicity and increased respiration in citrus fruits

“…Likewise, changes in the ethylene-treated oranges agree with the idea that the ethylene-induced acclimation of plants to stress involves oxidative stress-related responses (Munn e-Bosch et al, 2004). An excess of ethylene may favor ROS and senescence (Hodges and Forney, 2000) and some of the 1-MCP-induced responses showed similarities to the responses related to the postharvest senescence process in citrus fruit (Ding et al, 2015). However, besides NCPP incidence, there were no relevant differences in external appearance among AC, EC and 1-MCP-treated fruits.…”

Regulation of cuticle formation during fruit development and ripening in ‘Newhall’ navel orange ( Citrus sinensis Osbeck) revealed by transcriptomic and metabolomic profiling

“…The previous study showed that those genes encoding lipase showed higher expression during storage in Newhall fruit peel [39], which suggested that cuticular membrane might be degraded by lipase. In Arabidopsis, most of cutin-deficient mutants had a stronger resistance to Botrytis cinerea than the wild type [40].…”

Integrated Analysis of Transcriptomic and Metabolomic Data Reveals the Mechanism by Which LED Light Irradiation Extends the Postharvest Quality of Pak-choi (Brassica campestris L. ssp. chinensis (L.) Makino var. communis Tsen et Lee)

“…The control group was stored under dark conditions, while the LED-treated group was stored under continuous irradiation with white LED light at wavelengths of 448 nm and 549 nm at a light intensity of approximately 10 µmol m −2 s −1 . Other parameters of white LED light were red (600-700 nm) at 22.221 µmol m −2 s −1 , green (500-599 nm) at 43.325 µmol m −2 s −1 , blue (400-499 nm) at 25.461 µmol m −2 s −1 , far-red (701-780 nm) at 2.3373 µmol m −2 s −1 , and PPF (400-700 nm) at 91.0 µmol m −2 s −1 . The red/far-red ratio was 9.51 and the red/blue ratio was 0.73.…”

“…The integrated use of transcriptomics and metabolomics has been used to investigate the metabolic changes that occur during the postharvest storage of produce. For example, Ding et al [22] identified a network of processes that occur during the postharvest senescence process in citrus fruits. Thus, in the present study, we augmented transcriptomic profiling and performed a joint analysis with previous metabolomics to improve understanding of the response of harvested pak-choi to LED irradiation.…”