The sprout inhibitors chlorpropham and 1,4-dimethylnaphthalene elicit different transcriptional profiles and do not suppress growth through a prolongation of the dormant state

Abstract

Chlorpropham (CIPC) and 1,4-dimethylnapthalene (DMN) are used to control postharvest sprouting of potato tubers. CIPC alters microtubule structure and function resulting in inhibition of cell division. The mechanism of action of DMN is unknown but, because it is a natural product found in potato tubers, there is speculation that it inhibits sprout growth by prolonging the dormant state. To address this issue, the effects of CIPC and DMN on abscisic acid (ABA) content and gene expression in potato tuber meristems were determined and compared to those found in dormant and non-dormant meristems. Dormancy progression was accompanied by a dramatic decline in ABA content and the ABA levels in meristems isolated from CIPC- and DMN- treated tubers were identical to the levels found in nondormant meristems demonstrating that sprout repression is not a function of elevated ABA. Evaluation of transcriptional profiles using cDNA microarrays demonstrated that there were similarities between CIPC- and DMN- treated tuber tissues particularly in transcripts that encode phosphatases and proteins associated with oxygen-related metabolism. Despite these similarities, there were significant differences in transcript profiles derived from treatment with either CIPC or DMN and the dormant state. These results suggested the mechanisms-of -action of DMN and CIPC are distinct and not due to a prolongation of the normal dormant condition.

Regulation of potato tuber sprouting

“…The synthetic chlorpropham (isopropyl N-chlorophenylcarbamate, CIPC) is the most effective sprout inhibitor which prevents tuber sprouting by interfering with its cell division (Vaughn and Lehnen 1991;Campbell et al 2010). However, its application raises environmental and consumer concerns.…”

Dose- and tissue-specific interaction of monoterpenes with the gibberellin-mediated release of potato tuber bud dormancy, sprout growth and induction of α-amylases and β-amylases

“…The tuber is usually dormant upon harvest, which means that the bud meristems are in an arrested state and visible bud sprout growth (sprouting) is thereby blocked. Potato tuber dormancy is associated with down-regulated cell cycle genes and increased ABA contents in the bud meristems when compared with the nondormant state (Destefano-Beltran et al 2006a, b;Campbell et al 2010). Bud dormancy release occurs after a period of tuber storage and is visible as post-harvest sprouting.…”

“…CIPC [chlorpropham; isopropyl N-(3-chlorophenyl) carbamate] is the most effective post-harvest bud sprout inhibitor registered for use in potato tuber storage (Kleinkopf et al 2003;Eshel et al 2009;Campbell et al 2010;Teper-Bamnolker et al 2010). CIPC inhibits bud sprouting following loss of tuber dormancy by interfering with cell division; it modifies spindle formation by altering microtubule structure and thereby inhibits mitosis.…”

Sprout suppression on potato: need to look beyond CIPC for more effective and safer alternatives

“…The CIPC is applied first (16-22 g per tonne of potatoes one time as a single application) and then the 1, 4-DMN is applied. In comparison with the CIPC treatment alone; 1, 4-DMN is found to be effective in achieving adequate suppression of sprouts on potatoes if potatoes are previously treated with CIPC (Kleinkopf et al 2003;Campbell et al 2010). Now for long-term control of sprouting, in addition to the preharvest treatment of potato crop with maleic hydrazide, CIPC can be applied to the harvested potatoes during the storage (NAPPO 2013).…”