"Tomato roots in water stress- from big data to regulation of cell type development"

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Thursday 06 September 2018, 11:00 - 12:30


Tomato (Solanum lycopersicum) is economically the most important vegetable crop world-wide. Although tomato is cultivated in the field in hot environments, it is sensitive to drought. In contrast, tomato wild relative S. pennellii is drought-tolerant. We set out to study how drought and flooding are integrated to S. lycopersicum cv. M82 and S. pennellii root cellular anatomy and cellular development. Furthermore, to elucidate the molecular events underlying the developmental programs of the cell types, we generated marker lines and cell type-specific gene expression profiles in control and water-deficit conditions. The marker lines utilized eleven different cell and tissue type-specific promoters and two different transgenic tags; a nuclear-envelope tag for Isolation of Nuclei Tagged in specific Cell-Types (INTACT) and a polysome tag for Translating Ribosome Affinity Purification (TRAP). We used these techniques to isolate nuclei and polysomes in cell type-specific fashion and to subsequently profile different levels of regulation of gene expression: the nuclear chromatin accessibility and the ribosomal transcriptome (“translatome”).
Both S. lycopersicum and S. pennellii roots have exodermis, a barrier cell type absent in Arabidopsis. The exodermis is the outermost cortex layer with lignin and suberin deposited to the cell wall to provide the barrier functionality. We found that S. lycopersicum exodermis suberization increased in 10-day water deficit treatment, providing protection for the root against water loss. Interestingly, the drought-tolerant S. pennellii has a constitutively highly suberized exodermis and we observed no change in suberization in response to water deficit. Using the cell type-specific translatome data, we have identified a putative suberin biosynthesis pathway as well as putative regulators of the drought-responsive exodermis suberization. We are currently testing the gene function of the top regulatory candidates, two MYB transcription factors, through ectopic expression and genome editing in tomato. 

Location Jozef Schell Seminar Room
Contact Assistant Prof Kaisa Kajala
Plant Ecophysiology
Utrecht University
Institute of Environmental Biology (IEB)