Programmed cell death occurs asymmetrically during abscission in tomato

Tal Bar-Dror, Marina Dermastia, Aleš Kladnik, Magda Tušek Žnidarič, Maruša Pompe Novak, Shimon Meir, Shaul Burd, Sonia Philosoph-Hadas, Naomi Ori, Lilian Sonego, Martin B. Dickman, Amnon Lers*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

Abscission occurs specifically in the abscission zone (AZ) tissue as a natural stage of plant development. Previously, we observed delay of tomato (Solanum lycopersicum) leaf abscission when the LX ribonuclease (LX) was inhibited. The known association between LX expression and programmed cell death (PCD) suggested involvement of PCD in abscission. In this study, hallmarks of PCD were identified in the tomato leaf and flower AZs during the late stage of abscission. These included loss of cell viability, altered nuclear morphology, DNA fragmentation, elevated levels of reactive oxygen species and enzymatic activities, and expression of PCD-associated genes. Overexpression of antiapoptotic proteins resulted in retarded abscission, indicating PCD requirement. PCD, LX, and nuclease gene expression were visualized primarily in the AZ distal tissue, demonstrating an asymmetry between the two AZ sides. Asymmetric expression was observed for genes associated with cell wall hydrolysis, leading to AZ, or associated with ethylene biosynthesis, which induces abscission. These results suggest that different abscission-related processes occur asymmetrically between the AZ proximal and distal sides. Taken together, our findings identify PCD as a key mechanism that occurs asymmetrically during normal progression of abscission and suggest an important role for LX in this PCD process.

Original languageAmerican English
Pages (from-to)4146-4163
Number of pages18
JournalPlant Cell
Volume23
Issue number11
DOIs
StatePublished - Nov 2011

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