Articles
TRANSCRIPTIONAL ANALYSIS SUGGESTS SPROUT SUPPRESSION OF ONION DURING STORAGE USING ETHYLENE AND/OR 1-MCP IS MEDIATED VIA DIFFERENTIAL MODES OF ACTION
Article number
969_23
Pages
175 – 182
Language
English
Abstract
Onion is regarded as non-climacteric.
In climacteric produce, exogenous ethylene generally results in ripening-related changes, however in onion, ethylene can suppress sprouting.
The ethylene binding inhibitor, 1-MCP can also suppress sprout growth in onion although it is unknown how ethylene and 1-MCP elicit the same response.
In this study, Sherpa onions were treated with 10 μl L-1 ethylene or 1 μl L-1 1-MCP individually or in combination for 24 h at 20°C immediately after harvest.
The onions were then stored for 25 weeks (6 weeks curing at 28°C then transferred to 1°C). To investigate the effects of ethylene and 1-MCP at the transcriptional level, a newly developed onion microarray containing 13,310 tentatively annotated probes was used.
These data were compared with changes in onion bulb physiology.
After 25 weeks storage, onions treated with 1-MCP alone or in combination with ethylene had significantly shorter sprouts than the control bulbs.
Onion respiration rate immediately after treatment was highest in onions treated with ethylene alone followed by ethylene and 1-MCP in combination, 1-MCP alone and the control bulbs.
Genes differentially regulated in response to ethylene and/or 1-MCP were clustered using K-means cluster analysis; three of these clusters revealed sets of genes differentially regulated between treatment regimes.
A cluster containing probes representing transcripts down-regulated by ethylene but not in the presence of 1-MCP suggests these transcripts may only respond to specific ethylene receptors or group of ethylene receptors which bind 1-MCP. Another cluster contained a set of probes representing transcripts only up-regulated by 1-MCP alone but down regulated by ethylene alone or in combination with 1-MCP which suggests that these transcripts respond to ethylene by a receptor or group of receptors not bound by 1-MCP. Taken together, physiological and molecular results suggest that ethylene and 1-MCP suppress sprouting in onion via different mechanisms.
In climacteric produce, exogenous ethylene generally results in ripening-related changes, however in onion, ethylene can suppress sprouting.
The ethylene binding inhibitor, 1-MCP can also suppress sprout growth in onion although it is unknown how ethylene and 1-MCP elicit the same response.
In this study, Sherpa onions were treated with 10 μl L-1 ethylene or 1 μl L-1 1-MCP individually or in combination for 24 h at 20°C immediately after harvest.
The onions were then stored for 25 weeks (6 weeks curing at 28°C then transferred to 1°C). To investigate the effects of ethylene and 1-MCP at the transcriptional level, a newly developed onion microarray containing 13,310 tentatively annotated probes was used.
These data were compared with changes in onion bulb physiology.
After 25 weeks storage, onions treated with 1-MCP alone or in combination with ethylene had significantly shorter sprouts than the control bulbs.
Onion respiration rate immediately after treatment was highest in onions treated with ethylene alone followed by ethylene and 1-MCP in combination, 1-MCP alone and the control bulbs.
Genes differentially regulated in response to ethylene and/or 1-MCP were clustered using K-means cluster analysis; three of these clusters revealed sets of genes differentially regulated between treatment regimes.
A cluster containing probes representing transcripts down-regulated by ethylene but not in the presence of 1-MCP suggests these transcripts may only respond to specific ethylene receptors or group of ethylene receptors which bind 1-MCP. Another cluster contained a set of probes representing transcripts only up-regulated by 1-MCP alone but down regulated by ethylene alone or in combination with 1-MCP which suggests that these transcripts respond to ethylene by a receptor or group of receptors not bound by 1-MCP. Taken together, physiological and molecular results suggest that ethylene and 1-MCP suppress sprouting in onion via different mechanisms.
Publication
Authors
G.A. Chope, K. Cools, L.A. Terry, J.P. Hammond, A.J. Thompson
Keywords
clustering, microarray, non-climacteric, respiration rate
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