Crop production depends primarily on seed vigor, which relates to fast seed germination and robust seedling establishment under a fluctuating environment. The ability of a seed to germinate rapidly and in the right season is of vital importance from an ecological and economical point of view. After germination, the seedling undergoes a transition phase in which the change from heterotrophic to autotrophic growth is key for the establishment of the seedling and its survival. Due to the fragility of these early growth stages, their swiftness and resilience will affect later developmental stages and crop yield.

To understand how plants integrate environmental information into growth programs, our group have been studying seed vigor traits and their underlying molecular mechanisms. Results obtained by studying the model plant Arabidopsis thaliana are guiding our efforts to translate this knowledge to improve crop performance. To achieve our goals, we have put in place several complementary strategies and a broad set of state-of-the art methods and new techniques developed in our lab. In the last few years, we have identified different molecular mechanisms that regulate seed vigor, specifically dormancy and germination, providing important conceptual insights into the biomechanics of these traits. More recently, we have discovered a novel molecular mechanism mediating nutrient stress responses during and upon seedling establishment with a high biotechnological potential to bolster crop tolerance to stresses.

Representative publications

Carrera-Castaño G, Fañanás-Pueyo I, Celada-Bustillos L, Calleja-Cabrera J, Molinelli-Rubiato H, Contreras A, Maika JE, Simon R, Gómez L, Pernas M, Oñate-Sánchez L (2026) Membrane-associated DELLA degradation modulates growth under carbon/nitrogen imbalance. The Plant Cell 38(2): 1-18 (doi: 10.1093/plcell/koag013)

Carrera-Castaño G, Mira S, Fañanás-Pueyo I, Sánchez-Montesino R, Contreras Á, Weiste C, Dröge-Laser W, Gómez L, Oñate-Sánchez L (2024) Complex control of seed germination timing by ERF50 involves RGL2 antagonism and negative feedback regulation of DOG1. New Phytologist 242(5): 2026-2042

Sánchez-Montesino R, Bouza-Morcillo L, Marquez J, Ghita M, Duran-Nebreda S, Gómez L, Holdsworth MJ, Bassel G, Oñate-Sánchez L (2019) A Regulatory Module Controlling GA-Mediated Endosperm Cell Expansion Is Critical for Seed Germination in Arabidopsis. Molecular Plant 12(1): 71-85

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. The Plant Cell 26(7): 2905-2919.

CURRENT RESEARCH

Seedling establishment under nutrient imbalance as a gateway to improve stress tolerance in crops

Plant growth and development must be coordinated with nutrient availability. Carbon (C) and nitrogen (N) are the two most abundant elements in plant cells, being N the main limiting element in most agricultural soils. Use of fertilizers to increase N availability has a negative economic impact on crop yield and affect human and environmental wellbeing. Responses to either of these nutrients have been studied extensively. The balance between C- and N-compounds has received less attention despite the fact that the C/N ratio, in addition to the C status or the N availability alone, significantly affects plant growth and development. High C/N ratios (C/N stress) have a negative impact on plant development, including the phase transition from heterotrophic to autotrophic growth crucial for seedling establishment and plant survival.

We have obtained genetic, molecular and physiological evidence supporting a novel role for DELLA proteins to control growth under C/N stress through a non-nuclear mechanism that regulates their stability and independent of the canonical GA-GID1 pathway. Although C/N stress enhances DELLA accumulation by reducing GA levels, it also promotes their ubiquitination and degradation via interaction with the ATL31 E3-ligase at the membrane. Moreover, phenotypic traits known to be altered by DELLA levels are not affected by enhanced ATL31 expression in the absence of stress. We propose that this mechanism fine-tunes DELLA-mediated C/N stress responses without adverse effects on plant development (Figure 1). Physiological, genetic and molecular studies carried out in collaboration with Dr. Mónica Pernas (CBGP) indicate the existence of conservation of the C/N response in crops. Ongoing research in the model plant Arabidopsis and tomato crops is unravelling the full potential of this mechanism to enhance stress tolerance as well as shedding valuable light to design precision breeding and/or biotechnological tools.

Figure 1. Under balanced C/N conditions, rising in N levels promotes DELLA degradation by the GA pathway and ATL31 expression is reduced. C/N stress represses the GA pathway and enhances ATL31 mRNA and protein levels. ATL31 interacts in turn with specific DELLAs in the plasma membrane, targeting them for degradation (Carrera-Castaño et al., The Plant Cell, in press).