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Article|01 Jun 2018|OPEN
The Tomato Hybrid Proline-rich Protein regulates the abscission zone competence to respond to ethylene signals
Srivignesh Sundaresan1,2,3, Sonia Philosoph-Hadas1, Chao Ma4,5, Cai-Zhong Jiang4,6, Joseph Riov2, Raja Mugasimangalam7, Betina Kochanek1, Shoshana Salim1, Michael S. Reid4 & Shimon Meir1,
1Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), The Volcani Center, Rishon LeZiyon, Israel
2The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
3Present address: Department of Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore, India
4Department of Plant Sciences, University of California, Davis, CA, USA
5Present address: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, China Agricultural University, Beijing, China
6Crops Pathology & Genetic Research Unit, USDAARS, Davis, CA, USA
7Department of Bioinformatics, QTLomics Technologies Pvt. Ltd, Bangalore, India

Horticulture Research 5,
Article number: 28 (2018)
doi: 10.1038/hortres.2018.28
Views: 527

Received: 20 Dec 2017
Revised: 05 Mar 2018
Accepted: 08 Mar 2018
Published online: 01 Jun 2018

Abstract

The Tomato Hybrid Proline-rich Protein (THyPRP) gene was specifically expressed in the tomato (Solanum lycopersicum) flower abscission zone (FAZ), and its stable antisense silencing under the control of an abscission zone (AZ)-specific promoter, Tomato Abscission Polygalacturonase4, significantly inhibited tomato pedicel abscission following flower removal. For understanding the THyPRP role in regulating pedicel abscission, a transcriptomic analysis of the FAZ of THyPRP-silenced plants was performed, using a newly developed AZ-specific tomato microarray chip. Decreased expression of THyPRP in the silenced plants was already observed before abscission induction, resulting in FAZ-specific altered gene expression of transcription factors, epigenetic modifiers, post-translational regulators, and transporters. Our data demonstrate that the effect of THyPRP silencing on pedicel abscission was not mediated by its effect on auxin balance, but by decreased ethylene biosynthesis and response. Additionally, THyPRP silencing revealed new players, which were demonstrated for the first time to be involved in regulating pedicel abscission processes. These include: gibberellin perception, Ca2+-Calmodulin signaling, Serpins and Small Ubiquitin-related Modifier proteins involved in post-translational modifications, Synthaxin and SNARE-like proteins, which participate in exocytosis, a process necessary for cell separation. These changes, occurring in the silenced plants early after flower removal, inhibited and/or delayed the acquisition of the competence of the FAZ cells to respond to ethylene signaling. Our results suggest that THyPRP acts as a master regulator of flower abscission in tomato, predominantly by playing a role in the regulation of the FAZ cell competence to respond to ethylene signals.