STUDYING GIBBERELLIN SIGNALLING TO IMPROVE SEED GERMINATION AND PLANT GROWTH UNDER STRESS
- Fañanás Pueyo, Iris - PhD Student
- Mira Pérez, Sara - Visiting Scientist
- Molinelli Rubiato, Hector - PhD Student
Seeds are plant organs that play a central role in the life cycle of plants as well as in the everyday life of humans and livestock. Crop yields depend primarily on seed vigor, which relates to fast seed germination and robust seedling establishment under diverse environments. Gibberellins (GAs) are phytohormones indispensable for seed germination and also required for normal vegetative and reproductive growth. Although several stress conditions, such as drought and salinity, are known to decrease GAs, thus negatively affecting plant growth and productivity, this response increases plant survival.
We are studying seed germination and molecular mechanisms underlying responses to GAs to understand how plants integrate environmental information into growth programs aiming to improve crop performance. To carry out our studies we are using model and crop plants such as Arabidopsis thaliana, Brassica napus (rapeseed) and poplar, the latter one in collaboration with Dr. Luis Gómez.
What are the mechanisms controlling cell growth that promote seed germination?
From a mechanistic point of view, seed germination results from a balance between a physical restriction imposed by the embryo-surrounding tissues (endosperm and testa) and the ability of the embryo to grow and protrude. We have found that GA-signalling in the Arabidopsis embryo epidermis (along the embryonic axis) is required for proper germination and that the underlying molecular mechanism is coordinating growth of the epidermis with that of inner tissues (Rombolá-Caldentey et al., 2014; Figure 1). This mechanism was found later to be controlling cotton fibre cell elongation, indicating that it has been recruited by other developmental stages and suggesting that it is highly conserved in plants. Recently, we have also demonstrated that endosperm cell expansion is crucial for germination and two transcription factors play pivotal roles in this process by upregulating cell-wall remodelling enzyme gene expression upon perception of signals from embryo (Sánchez-Montesino et al., in press; Figure 2).
How is growth affected by the environment?
Global warming associated to climate change has become a serious threat worldwide, and high temperature is a major environmental factor limiting crop productivity. We are using rapeseed accessions to analyze the effect of temperature on seed vigour traits and study the molecular mechanisms underlying those responses (Figure 3).
By screening a gain-of-function seed library we have identified mutants able to germinate faster under low GA levels similar to those produced by stress conditions. Remarkably, some of these mutants, also have improved vegetative growth suggesting the existence of mechanisms unlinking growth and stress. Molecular, genetic and physiological studies are revealing that one of those mutants plays a dominant role in the control of growth by light in the seed and explains how this regulation is reverted upon germination.
How can we apply this knowledge to improve crop performance?
- Based on our above studies, we are using computational and molecular tools to generate allelic versions of selected genes that could be used for crop improvement.
- We are also using reporter genes coupled to appropriate marker genes to screen for natural compounds that modify seed germination and/or vegetative growth (Figure 4).
- In most tree-breeding programs, the main objective is to increase the level of biomass and abiotic stress resistance. We are analyzing, both phenotypically and molecularly, transgenic hybrid poplars engineered to modify GA levels.
2018-2021: Improving seed vigour in Brassica crops. Programa Severo Ochoa (EoI-TSP2-05). PI: Luis Oñate-Sánchez.
2017-2019: Arabidopsis genes regulating seed germination and growth as targets to improve crop biomass and yield. MINECO (BIO2016-77840-R). PI: Luis Oñate-Sánchez.
2014-2017: Studying gibberellin signalling to improve seed germination and resistance to stress. MINECO (BIO2013-46076-R). PI: Luis Oñate-Sánchez.
Oñate-Sánchez, L., Verdonk, J.C. 2021. Citrate-Citric Acid RNA Isolation (CiAR) for Fast, Low-Cost, and Reliable RNA Extraction from Multiple Plant Species and Tissues. Current Protocols 1, e298. DOI: 10.1002/cpz1.298
Contreras, Á., Merino, I., Álvarez, E., Bolonio, D., Ortiz, J.-E., Oñate-Sánchez, L., Gómez, L. 2021. A poplar short-chain dehydrogenase reductase plays a potential key role in biphenyl detoxification. Proceedings of the National Academy of Sciences USA 118, e2103378118. DOI: 10.1073/pnas.2103378118
Calleja-Cabrera, J., Boter, M., Oñate-Sánchez, L., Pernas, M. 2020. Root Growth Adaptation to Climate Change in Crops. Frontiers in Plant Science 11, 544. DOI: 10.3389/fpls.2020.00544
Carrera-Castaño, G., Calleja-Cabrera, J., Pernas, M., Gómez, L., Oñate-Sánchez, L. 2020. An Updated Overview on the Regulation of Seed Germination. Plants 9, 703. DOI: 10.3390/plants9060703
Boter, M., Calleja-Cabrera, J., Carrera-Castaño, G., Wagner, G., Hatzig, S.V., Snowdon, R.J., Legoahec, L., Bianchetti, G., Bouchereau, A., Nesi, N., Pernas, M., Oñate-Sánchez, L. 2019. An Integrative Approach to Analyze Seed Germination in Brassica napus. Frontiers in Plant Science 10. DOI: 10.3389/fpls.2019.01342
Sánchez-Montesino, R.; Bouza-Morcillo, L.; Marquez, J.; Ghita, M.; Duran-Nebreda, S.; Gómez, L.; Holdsworth, M.J.; Bassel, G.; Oñate-Sánchez, L. 2019. "A regulatory module controlling GA-mediated endosperm cell expansion is critical for seed germination in Arabidopsis". Molecular Plant. DOI: 10.1016/j.molp.2018.10.009.
Gomez, L., Contreras, A., Bolonio, D., Quintana, J., Oñate-Sanchez, L., Merino, I. 2019. Phytoremediation with trees, in: Advances in Botanical Research. Academic Press. DOI: 10.1016/bs.abr.2018.11.010
Sánchez-Montesino, R; Oñate-Sánchez, L. 2018. "Screening arrayed libraries with DNA and protein baits to identify interacting proteins", p. 131-149. In L. Oñate-Sánchez (ed.), Two-Hybrid Systems: Methods and Protocols. Springer New York, New York, NY. DOI: 10.1007/978-1-4939-7871-7_9".
Sánchez-Montesino, R; Oñate-Sánchez, L. 2017. "Yeast one- and two-hybrid high-throughput screenings using arrayed libraries", p. 47-65. In K. Kaufmann and B. Mueller-Roeber (eds.), Plant Gene Regulatory Networks: Methods and Protocols. Springer New York, New York, NY. DOI: 10.1007/978-1-4939-7125-1_5".
Ballester, P; Navarrete-Gómez, M; Carbonero, P; Oñate-Sánchez, L; Ferrándiz, C. 2015. "Leaf expansion in Arabidopsis is controlled by a TCP-NGA regulatory module likely conserved in distantly related species". Physiologia Plantarum. DOI: 10.1111/ppl.12327".
Thatcher, LF; Kamphuis, LG; Hane, JK; Oñate-Sánchez, L; Singh, KB. 2015. "The Arabidopsis KH-Domain RNA-Binding protein ESR1 functions in components of jasmonate signalling, unlinking growth restraint and resistance to stress". PLoS One. DOI: 10.1371/journal.pone.0126978".
Coego, A; Brizuela, E; Castillejo, P; Ruíz, S; Koncz, C; del Pozo, JC; Piñeiro, M; Jarillo, JA; Paz-Ares, J; León, J; Transplanta Consortium, T. 2014. "The TRANSPLANTA collection of Arabidopsis lines: a resource for functional analysis of transcription factors based on their conditional overexpression". Plant Journal. DOI: 10.1111/tpj.12443".
Rombolá-Caldentey, B; Rueda-Romero, P; Iglesias-Fernández, R; Carbonero, P; Oñate-Sánchez, L. 2014. "Arabidopsis DELLA and two HD-ZIP transcription factors regulate GA signaling in the epidermis through the L1 box cis-element". Plant Cell. DOI: 10.1105/tpc.114.127647".
Marin-de la Rosa, N; Sotillo, B; Miskolczi, P; Gibbs, DJ; Vicente, J; Carbonero, P; Onate-Sanchez, L; Holdsworth, MJ; Bhalerao, R; Alabadi, D; Blazquez, MA. 2014. "Large-scale identification of gibberellin-related transcription factors defines group VII ETHYLENE RESPONSE FACTORS as functional DELLA partners". Plant Physiology. DOI: 10.1104/pp.114.244723".
Iglesias-Fernández, R; Wozny, D; Iriondo-de Hond, M; Oñate-Sánchez, L; Carbonero, P; Barrero-Sicilia, C. 2014. "The AtCathB3 gene, encoding a cathepsin B-like protease, is expressed during germination of Arabidopsis thaliana and transcriptionally repressed by the basic leucine zipper protein GBF1". Journal of Experimental Botany. DOI: 10.1093/jxb/eru055".
Rueda-Romero P, Barrero-Sicilia C, Gómez-Cadenas A, Carbonero P and Oñate-Sánchez L* (2012) Arabidopsis thaliana DOF6 negatively affects germination in non-after-ripened seeds and interacts with TCP14. Journal of Experimental Botany 63: 1937-1949.
Iglesias-Fernández, R; Barrero-Sicilia, C; Carrillo-Barral, N; Oñate-Sánchez, L; Carbonero, P. 2013. "Arabidopsis thaliana bZIP44: a transcription factor affecting seed germination and expression of the mannanase encoding gene AtMAN7". Plant Journal. DOI: 10.1111/tpj.12162".
Castrillo G, Turck F, Leveugle M, Lecharny A, Carbonero P, Coupland G, Paz-Ares J and Oñate-Sánchez L* (2011) Speeding cis-trans regulation discovery by phylogenomic analyses coupled with screenings of an arrayed library of Arabidopsis transcription factors. PLoS ONE 6(6): e21524.
Wehner N, Hartmann L, Ehlert A, Böttner S, Oñate-Sánchez L and Dröge-Laser W (2011) High-throughput protoplast trans activation (PTA) system for the analysis of Arabidopsis transcription factor function. The Plant Journal 68: 560-569.