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Plant Cell Environ. 2017 Oct;40(10):2381-2392. doi: 10.1111/pce.13044. Epub 2017 Aug 25.

Vacuolar processing enzyme activates programmed cell death in the apical meristem inducing loss of apical dominance.

Author information

1
Department of Postharvest and Food Sciences, ARO, Agricultural Research Organization, The Volcani Center, HaMacabim 68, 75359, Rishon LeZion, Israel.
2
The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture Food and Environment, The Hebrew University of Jerusalem, Herzl 267, 76100, Rehovot, Israel.
3
Department of Ornamental Horticulture, ARO, Agricultural Research Organization, The Volcani Center, HaMacabim 68, 75359, Rishon LeZion, Israel.
4
Department of Vegetables and Field Crops, ARO, Agricultural Research Organization, The Volcani Center, HaMacabim 68, 75359, Rishon LeZion, Israel.
5
Institute of Plant Sciences, ARO, The Volcani Center, HaMacabim 68, 75359, Rishon LeZion, Israel.
6
Department of Biological Services, Weizmann Institute of Science, Herzl 234, 7610001, Rehovot, Israel.
7
Plant Chemetics Laboratory, Department of Plant Sciences, University of Oxford, South Parks Road Oxford, OX1 3RB, Oxford, UK.

Abstract

The potato (Solanum tuberosum L.) tuber is a swollen underground stem that can sprout in an apical dominance (AD) pattern. Bromoethane (BE) induces loss of AD and the accumulation of vegetative vacuolar processing enzyme (S. tuberosum vacuolar processing enzyme [StVPE]) in the tuber apical meristem (TAM). Vacuolar processing enzyme activity, induced by BE, is followed by programmed cell death in the TAM. In this study, we found that the mature StVPE1 (mVPE) protein exhibits specific activity for caspase 1, but not caspase 3 substrates. Optimal activity of mVPE was achieved at acidic pH, consistent with localization of StVPE1 to the vacuole, at the edge of the TAM. Downregulation of StVPE1 by RNA interference resulted in reduced stem branching and retained AD in tubers treated with BE. Overexpression of StVPE1 fused to green fluorescent protein showed enhanced stem branching after BE treatment. Our data suggest that, following stress, induction of StVPE1 in the TAM induces AD loss and stem branching.

KEYWORDS:

Solanum tuberosum (potato); apical dominance (AD); caspase; stem branching; tuber apical meristem (TAM); vacuolar processing enzyme (VPE)

PMID:
28755442
DOI:
10.1111/pce.13044
[Indexed for MEDLINE]

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