Projects / Programmes source: ARIS

Asymmetry of cellular processes in abscission of leaves and flowers of tomato

Research activity

Code Science Field Subfield
1.03.04  Natural sciences and mathematics  Biology  Plant physiology 

Code Science Field
B310  Biomedical sciences  Physiology of vascular plants 

Code Science Field
1.06  Natural Sciences  Biological sciences 
abscission; tomato; Solanum Lycopersicum; programmed cell death; RNase LX; ethylene; endoreduplication
Evaluation (rules)
source: COBISS
Researchers (9)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  17078  PhD Sabina Anžlovar  Biology  Researcher  2013 - 2016  67 
2.  08280  PhD Marina Dermastia  Biology  Researcher  2013 - 2016  872 
3.  15456  PhD Jasna Dolenc Koce  Biology  Researcher  2013 - 2016  217 
4.  20070  PhD Aleš Kladnik  Biology  Head  2013 - 2016  174 
5.  20428  PhD Matevž Likar  Biology  Researcher  2013 - 2016  281 
6.  19137  Tjaša Pogačnik Lipovec  Biotechnology  Technical associate  2013 - 2016  11 
7.  18467  PhD Maruša Pompe Novak  Biotechnology  Researcher  2013 - 2016  291 
8.  05229  PhD Maja Ravnikar  Biotechnology  Researcher  2013 - 2016  1,369 
9.  09864  PhD Magda Tušek Žnidarič  Biology  Researcher  2013 - 2016  414 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0105  National Institute of Biology  Ljubljana  5055784  13,251 
2.  0481  University of Ljubljana, Biotechnical Faculty  Ljubljana  1626914  66,273 
Abscission is a highly regulated process in which various organs, including leaves, flowers and fruits, are separated from the mother plant as a natural stage of plant development. Abscission occurs specifically in the abscission zone (AZ) tissue. AZ is located at the base of the organ to be shed, between fruit, flower or leaf and the plant body and is comprised of few layers of differentiated cells. AZ has a crucial role in the process. Not much is known about the molecular regulation of abscission. However, we have recently shown that the programmed cell death (PCD) is involved in the abscission of tomato leaves and flowers and suggested that various abscission-related processes occur asymmetrically between the AZ proximal and distal sides.   The proposed research is aimed to further characterize the identified asymmetry in the AZ and investigate its functional significance for the abscission process of flowers and leaves in tomato. We will investigate: (a) presumably high metabolic activity and membrane trafficking of cells at the proximal side of AZ, including the process of endoreduplication; (b) PCD type in AZ; (c) ethylene biosynthesis and perception; (d) cell wall metabolism/modification-related gene expression and global transcriptomic changes at the late stage of abscission; and (e) if inhibition of PCD leads to inhibition of abscission. We will examine changes of expression of specific genes using quantitative RT-PCR (qPCR), and use in situ hybridization and immunolocalization to determine in what AZ cells the gene transcripts and synthesized proteins are localized. Genes examined will be LX RNase, ACC oxidase (involved in ethylene biosynthesis), polygalacturonases, vacuolar protease with caspase-like activity, TBN1 nuclease and NADPH oxidase. Ultrastructural changes in AZ of leaves and flowers will be further examined using transmission electron microscopy (TEM). For achievements of some goals the approaches of functional genomics will be applied.   The results of the proposed research will supply information required for determining the functional significance of the observed asymmetry in the AZ and confirmation of the suggested hypotheses. The results could reveal novel and significant insights in three aspects: (1) the functional organization of the AZ in respect to the late execution stage of the process, and the significance of separating the execution machinery of abscission from the other involved factors (ethylene, LX RNase and PCD); (2) the role of a PCD process in ethylene-related processes or in another, yet unclear, way in the execution mechanism of abscission; (3) the role of ethylene as a signal for inducing LX RNase and PCD in abscission. The findings of this study will contribute to the overall basic knowledge on the process of abscission that is still extremely rudimentary. Results will be directly applicable in agriculture and biotechnology for controlled abscission of fruits and manipulation of abscission time.   The research will be conducted by three highly complementary and experienced research groups: two partner organizations in Slovenia – Laboratory for Experimental Botany at the Biotechnical Faculty, University of Ljubljana and the Department for Biotechnology and Systems biology at the National Institute of Biology. The third partner research group is the laboratory of Dr. Amnon Lers at the Volcani Center, Agricultural Research Organization, Department of Postharvest Science of Fresh Produce in Israel. All three partner laboratories have state-of the art equipment capable of producing high quality results that assure the total feasibility of the proposed project.
Significance for science
Because of the importance of plant organ detachment from the mother plant, especially detachment of fruits, the abscission process has been studied for decades. However, the research has been mostly limited to cell morphology in the abscission zone and as a consequence the basic knowledge on the molecular basis of the abscission is still rudimentary. Moreover, most of the findings on abscission come primarily from studying the abscission of petals of the model plant Arabidopsis. It is not clear whether the results of this experimental system are relevant to fruit and leaf abscission in crop plants such as tomato. The results of this study could significantly contribute to filling this gap and may lead to the development of biotechnological control of the process in the future. Results of the research on the association of LX RNase, role of the programmed cell death in abscission zone and elucidation of the site of ethylene biosynthesis open new biotechnological perspectives for the use of molecular tools for the improvement of those crops in which the yield is dependent on the abscission. Control over abscission and possible biotechnological manipulation of abscission of plant parts or seed dispersal would have a significant economical contribution. The research might lead toward advanced use of biotechnology in crop production for the benefit of agriculture and may be applied to different crop plants, most promising targets are ethylene perception and control of its biosynthesis, and cell separating enzymes that are crucial in the process of abscission.
Significance for the country
In this research we continued the international cooperation with the laboratory of Dr. Amnon Lers from the Volcani Center in Israel, which is a great opportunity to further share our valuable resources for scientific advancements that are of mutual interest to both Slovenia and Israel. We continued with combining the profound knowledge in the field of biotechnological applications in tomato production at the Israel side and Slovenian experiences with the whole plant and cellular physiology, microscope and imaging techniques, transcriptomics and bioinformatic approaches. This research might lead toward advances in use of biotechnology in different crops plants for the benefit of local and global agriculture.
Most important scientific results Annual report 2013, 2014, 2015, final report
Most important socioeconomically and culturally relevant results Annual report 2013, 2014, 2015, final report
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