A multidisciplinary approach to elucidate glandular trichome differentiation in tomato
Biochemie und Biophysik der Pflanzen
Genetik und Genomik der Pflanzen
Zusammenfassung der Projektergebnisse
Glandular trichomes are epidermal differentiations that protect the plant against a variety of aggressors through the chemicals that they produce and store, or secrete. In cultivated tomato (Solanum lycopersicum), a major horticultural crop, there are several types of glandular trichomes, of which type VI is the most abundant on the leaf surface. Volatiles terpenes are major products of the type VI trichomes and they are stored in an extracellular storage cavity located between the four glandular cells. In a related wild species, Solanum habrochaites, the overall architecture of type VI trichomes is the same, but the four glandular cells form a round shape and the storage cavity is much larger, representing around 65% of the total volume of the trichome head. This contributes to the much greater production capacity of type VI trichomes in S. habrochaites, and thereby to their increased resistance against herbivore pests. In this project, we investigated the reasons for these differences by a number of approaches. The first consisted in a thorough description of the development and anatomical features of type VI trichomes in both species. This showed that the sequence of development is very similar in both species and that the differences become visible when the trichomes enlarge. Immunostainings revealed the presence of specific cell wall components in distinct areas of the trichome glandular head. One interesting observation is the presence of an autofluorescent compound that is present in the early stages but disappears as the trichome matures. Chemical analysis indicates this is a derivative of riboflavin, but its function remains unclear. This autofluorescence was key in establishing a method to isolate trichomes at different development stages using fluorescence-activated cell sorting. This turned out to take a very long time to establish (around 1.5 years). One consequence was that it was difficult to make significant progress with the characterization of candidate genes within the time frame of the project. This is now under way using virus-induced gene silencing and transgenic approaches, including CRISPR/Cas9 gene editing. In parallel, a back-cross population of 116 individuals was generated with S. habrochaites LA1777 and S. lycopersicum Wva106, using the latter as the recurrent parent. A score was designed to reflect the shape of the type VI trichomes, which correlates with greater accumulation of terpenes. This was used to identify two major QTLs in the population, respectively on chromosome 1 and 7, each covering several hundred genes. Due to restricted recombination in these regions, the intervals could not be significantly reduced even in advanced populations. Nonetheless, using trichome transcriptome data available in the lab, a list of candidate genes was established. Further characterization of these by VIGS and gene editing is also in progress. In conclusion, this project allowed us to gain deeper insights in the development and physiology of tomato type VI trichomes. These results contribute to a long-term effort to introduce complex insect-resistance traits from related wild germplasm into cultivated tomato.
Projektbezogene Publikationen (Auswahl)
- (2014) Isoprenoid and metabolite profiling of plant trichomes. Methods Mol Biol. 1153:189-202
Balcke GU, Bennewitz S, Zabel S, Tissier A
(Siehe online unter https://dx.doi.org/10.1007/978-1-4939-0606-2_13) - (2015) The development of type VI glandular trichomes in the cultivated tomato Solanum lycopersicum and a related wild species S. habrochaites. BMC Plant Biol. 15:289
Bergau N, Bennewitz S, Syrowatka F, Hause G, Tissier A
(Siehe online unter https://doi.org/10.1186/s12870-015-0678-z) - (2016) Autofluorescence as a Signal to Sort Developing Glandular Trichomes by Flow Cytometry. Front Plant Sci. 2016 Jun 28;7:949
Bergau N, Navarette Santos A, Henning A, Balcke GU, Tissier A
(Siehe online unter https://doi.org/10.3389/fpls.2016.00949) - (2017) Multi-Omics of Tomato Glandular Trichomes Reveals Distinct Features of Central Carbon Metabolism Supporting High Productivity of Specialized Metabolites. Plant Cell. 29(5):960-983
Balcke GU, Bennewitz S, Bergau N, Athmer B, Henning A, Majovsky P, Jiménez-Gómez JM, Hoehenwarter W, Tissier A
(Siehe online unter https://doi.org/10.1105/tpc.17.00060) - (2017) Plant Volatiles: Going 'In' but not 'Out' of Trichome Cavities. Trends Plant Sci. 22(11):930-938
Tissier A, Morgan JA, Dudareva N
(Siehe online unter https://doi.org/10.1016/j.tplants.2017.09.001) - PhD Thesis, “Die Entwicklung der glandulären Typ VI Trichome von wilden und kultivierten Tomaten”. Martin-Luther Universität Halle-Wittenberg
Bergau, N
- (2018) QTL Mapping of the Shape of Type VI Glandular Trichomes in Tomato. Frontiers Plant Sci. 9, 01421
Bennewitz S, Bergau N, Tissier A
(Siehe online unter https://doi.org/10.3389/fpls.2018.01421) - Plant secretory structures: more than just reaction bags. (2018) Curr Opin Biotechnol. 49:73-79
Tissier A
(Siehe online unter https://doi.org/10.1016/j.copbio.2017.08.003)
