title: Programmed cell death occurs asymmetrically during abscission in tomato.
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.
authors: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
authors: Tal
authors: T
authors: Bar-Dror
authors: Marina
authors: M
authors: Dermastia
authors: Ales
authors: A
authors: Kladnik
authors: Magda Tusek
authors: MT
authors: Znidaric
authors: Marusa Pompe
authors: MP
authors: Novak
authors: Shimon
authors: S
authors: Meir
authors: Shaul
authors: S
authors: Burd
authors: Sonia
authors: S
authors: Philosoph-Hadas
authors: Naomi
authors: N
authors: Ori
authors: Lilian
authors: L
authors: Sonego
authors: Martin B
authors: MB
authors: Dickman
authors: Amnon
authors: A
authors: Lers
mesh_terms: D017209:Apoptosis; D002470:Cell Survival; D053938:DNA Fragmentation; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D035264:Flowers / Q000166:cytology / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000166:cytology* / Q000502:physiology; D008969:Molecular Sequence Data; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology / Q000502:physiology*; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D005030:Ethylenes; D017382:Reactive Oxygen Species; C036216:ethylene; D019255:NADPH Oxidases; D003851:Deoxyribonucleases; D004722:Endoribonucleases; C092634:ribonuclease LX; D010447:Peptide Hydrolases