Ethylene and 1-Methylcyclopropene Differentially Regulate Gene Expression during Onion Sprout Suppression    

Abstract

Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown how ethylene and 1-MCP elicit the same response. In this study, onions were treated with 10 mL L 21 ethylene or 1 mL L 21 1-MCP individually or in combination for 24 h at 20°C before or after curing (6 weeks) at 20°C or 28°C and then stored at 1°C. Following curing, a subset of these same onions was stored separately under continuous air or ethylene (10 mL L 21 ) at 1°C. Onions treated with ethylene and 1-MCP in combination after curing for 24 h had reduced sprout growth as compared with the control 25 weeks after harvest. Sprout growth following storage beyond 25 weeks was only reduced through continuous ethylene treatment. This observation was supported by a higher proportion of down-regulated genes characterized as being involved in photosynthesis, measured using a newly developed onion microarray. Physiological and biochemical data suggested that ethylene was being perceived in the presence of 1-MCP, since sprout growth was reduced in onions treated with 1-MCP and ethylene applied in combination but not when applied individually. A cluster of probes representing transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or in the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down-regulated a probe tentatively annotated as an ethylene receptor as well as ethylene-insensitive 3, suggesting that both treatments down-regulate the perception and signaling events of ethylene.

Ethylene inhibited sprouting of potato tubers by influencing the carbohydrate metabolism pathway

“…Ethylene might enhance the level of glucose (Foukaraki et al 2012), and the effect reversed with increasing content of ethylene. Cools et al (2011) observed that the levels of three sugars in onion were decreased to a variable extent on ethylene treatment which was consistent agreed with our results.…”

Transcriptome and phytohormone changes associated with ethylene-induced onion bulb dormancy

“…There are multiple reports describing the cross-talk of different phytohormones associated with dormancy break and sprout leaf elongation ( Hartmann et al, 2011 ; Cools et al, 2011 ; Chope et al, 2012 ), as well as with mobilisation of non-structural carbohydrate reserves ( Davis et al, 2007 ), particularly fructans ( Valluru, 2015 ; Ohanenye et al, 2019 ). In general, sprout elongation is thought to be initiated by the action of promoting hormones, such as CKs and gibberellins whilst being suppressed by the antagonist action of the inhibitory hormone ABA.…”

Ethylene treatment improves diosgenin accumulation in in vitro cultures of Dioscorea zingiberensis via up-regulation of CAS and HMGR gene expression

“…HMGR, catalyzing the conversion of HMG-CoA to mevalonic acid, is considered as a rate-limiting enzyme in cholesterol synthesis, and it also plays a critical role in controlling isoprenoid derivatives related pathways (Chen et al 2012). Cools et al (2011) found that ethylene treatment could increase in the expression of HMGR gene in onion. HMGR gene expression was induced by elicitor in Michelia chapensis (Cao et al 2011).…”