JXB Advance Access originally published online on March 19, 2008
Journal of Experimental Botany 2008 59(6):1175-1186; doi:10.1093/jxb/ern019
© 2008 The Author(s).
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RESEARCH PAPER |
Regulatory involvement of abscisic acid in potato tuber wound-healing
USDA-ARS, Northern Crop Science Laboratory, 1307 18th Street North, Fargo, ND 58105, USA
* To whom correspondence should be addressed. E-mail: ed.lulai{at}ars.usda.gov
Rapid wound-healing is crucial in protecting potato tubers from infection and dehydration. Wound-induced suberization and the accumulation of hydrophobic barriers to reduce water vapour conductance/loss are principal protective wound-healing processes. However, little is known about the cognate mechanisms that effect or regulate these processes. The objective of this research was to determine the involvement of abscisic acid (ABA) in the regulation of wound-induced suberization and tuber water vapour loss (dehydration). Analysis by liquid chromatography–mass spectrometry showed that ABA concentrations varied little throughout the tuber, but were slightly higher near the periderm and lowest in the pith. ABA concentrations increase then decrease during tuber storage. Tuber wounding induced changes in ABA content. ABA content in wound-healing tuber discs decreased after wounding, reached a minimum by 24 h, and then increased from the 3rd to the 7th day after wounding. Wound-induced ABA accumulations were reduced by fluridone (FLD); an inhibitor of de novo ABA biosynthesis. Wound-induced phenylalanine ammonia lyase activity was slightly reduced and the accumulation of suberin poly(phenolics) and poly(aliphatics) noticeably reduced in FLD-treated tissues. Addition of ABA to the FLD treatment restored phenylalanine ammonia lyase activity and suberization, unequivocally indicating that endogenous ABA is involved in the regulation of these wound-healing processes. Similar experiments showed that endogenous ABA is involved in the regulation of water vapour loss, a process linked to wax accumulation in wound-healing tubers. Rapid reduction of water vapour loss across the wound surface is essential in preventing desiccation and death of cells at the wound site; live cells are required for suberization. These results unequivocally show that endogenous ABA is involved in the regulation of wound-induced suberization and the processes that protect surface cells from water vapour loss and death by dehydration.
Key words: Abscisic acid, poly(aliphatic), poly(phenolic), potato, Solanum tuberosum L., suberin
Mention of company or trade name does not imply endorsement by the United States Department of Agriculture over others not named.
Received 30 September 2007; Revised 11 January 2008 Accepted 18 January 2008