Molecular Mechanisms Determining Seed Quality

The seed is the fundamental unit of plant propagation and the starting point of agricultural systems that sustain our economy. During its development, the seed acquires the characteristics that will determine its ability to germinate. Seed vigour is the sum of properties that determine its capacity to germinate rapidly and uniformly and to establish robust seedlings across a wide range of conditions. This concept integrates seed viability, size and reserve content, as well as its physiological state, all of which together condition successful seedling establishment. Understanding the molecular mechanisms involved in seed development, and especially those that determine seed quality, is a fascinating topic from a scientific perspective, but also has enormous applied potential given the economic importance of the seed market.

Seed longevity can be considered a process in which plant responses to both biotic and abiotic stress are intertwined. Unlike classical stress situations, it is not the plant that must be prepared to withstand adverse conditions, but rather the dry seed, which is metabolically more inert. Another distinctive aspect is that the germinating seed must cope with the consequences of stress that affected the embryo in the past, rather than in real time. Moreover, this aspect of stress biology integrates passive and active responses, protection and repair, and combines developmental processes (seed maturation and size, germination, plant establishment) with stress research. In recent years, our group has initiated the search for factors contributing to the genetic component of seed quality, focusing mainly on two aspects: longevity and size. Using the model plant Arabidopsis thaliana, we aim to identify genes relevant to seed deterioration resistance and to the development of larger, more nutrient-rich seeds. From a scientific perspective, we are interested in understanding how seeds grow, as well as how they prepare during maturation to withstand ageing.

Currently, several processes are being studied in detail: 1) How the environment during seed development influences longevity and other seed traits. We aim to disentangle the effects of environmental conditions during seed development on longevity, and to identify the regulatory pathways that translate environmental signals, as well as the processes and genes involved. Our results will allow greater control of seed viability, enabling future improvements in agricultural practices and seed conservation programs. 2) The role of flavonoids in seed protection and their connection with seed coat development. In addition to their proposed antioxidant role, these compounds may also act as signalling molecules. 3) How seed size is regulated and which genes are involved in this process, in order to design biotechnological strategies to obtain larger and more nutritious seeds.
From an applied perspective, we are interested in using this fundamental knowledge to initiate transfer strategies to crops of interest, and to provide recommendations to seed companies to improve seed longevity and quality.

Bacterial Effectors and Plant–Pathogen Interactions

The discovery of new bacterial effectors translocated into plant cells and the characterization of their activities, as well as the mechanisms by which they are recognized by the plant immune system, constitute a second research line in our group. In this area, we mainly focus on interactions between citrus plants and pathogens. Xanthomonas citri is the causal agent of citrus canker. This bacterium employs transcription activator-like effectors (TALEs) to facilitate infection. In recent years, our group has investigated how plants activate defense responses against specific TALEs. Our main objective is to identify R genes that trigger a hypersensitive response mediated by TALE-type avirulence factors. Huanglongbing (HLB) is a devastating citrus disease caused by bacteria of the genus Liberibacter. We are evaluating the role of potential bacterial effectors using heterologous systems and applying transcriptomic approaches to characterize plant responses to these bacteria in both susceptible and resistant interactions.

2015-2025

Alves MN, Cifuentes-Arenas J, Niñoles R, Raiol-Junior LL, Carvalho E, Quirós-Rodriguez I, Ferro JA, Licciardello C, Alquezar B, Carmona L, Forment J, Bombarely A, Wulff NA, Peña L, Gadea J. Transcriptomic analysis of early stages of ‘Candidatus Liberibacter asiaticus’ infection in susceptible and resistant species after inoculation by Diaphorina citri feeding on young shoots. Front Plant Sci. 2025 Feb 20;16:1502953

Lécureuil A, Corso M, Boutet S, Le Gall S, Niñoles R, Gadea J, Guerche P, Jasinski S. Innovative screening for mutants affected in seed oil/protein allocation identifies TRANSPARENT TESTA7 as a regulator of oil accumulation. Plant J. 2025 Jun;122(6):e70269

Roeschlin RA, Azad SM, Grove RP, Chuan A, García L, Niñoles R, Uviedo F, Villalobos L, Massimino ME, Marano MR, Boch J, Gadea J. Designer TALEs enable discovery of cell death-inducer genes. Plant Physiol. 2024 Jul 31;195(4):2985-2996.

Renard J, Bissoli G, Planes MD, Gadea J, Naranjo MÁ, Serrano R, Ingram G, Bueso E. Endosperm Persistence in Arabidopsis Results in Seed Coat Fractures and Loss of Seed Longevity. Plants (Basel). 2023 Jul 22;12(14):2726

Regina Niñoles, Paloma Arjona, Sepideh Mazhari Azad.…Jose Gadea*. Kaempferol-3-rhamnoside overaccumulation in flavonoid 3′-hydroxylase tt7 mutants compromises seed coat outer integument differentiation and seed longevity. New Phytologist, 2023 May;238(4):1461-1478

Regina Niñoles R, Carmen María Ruiz-Pastor, Paloma Arjona-Mudarra, …Jose Gadea*. Transcription Factor DOF4.1 Regulates Seed Longevity in Arabidopsis via Seed Permeability and Modulation of Seed Storage Protein Accumulation. Frontiers in Plant Sciences. 2022 Jul 1;13:915184

Regina Niñoles, Dolores Planes, Paloma Arjona…Jose Gadea*. Comparative analysis of wild-type accessions reveals novel determinants of Arabidopsis seed longevity. Plant Cell Environment. 2022 Sep;45(9):2708-2728

Lucila Garcia, L, María Celeste Molina, Bruna R, …Jose Gadea* and Maria Rosa Marano*. A serralysin-like protein of Candidatus Liberibacter asiaticus acts to modulate components of the bacterial extracellular matrix. Frontiers in Microbiology, 2022, 13: 1006962.

Joan Renard, Irene Martínez-Almonacid, Indira Queralta Castillo, Annika Sonntag, Aseel Hashim, Gaetano Bissoli, Laura Campos, Jesús Muñoz-Bertomeu, Regina Niñoles, Thomas Roach, Susana Sánchez-León, Carmen V. Osuna, José Gadea, Purificación Lisón, Ilse Kranner, Francisco Barro, Ramón Serrano, Isabel Molina, Eduardo Bueso*. Apoplastic lipid barriers regulated by conserved homeobox transcription 2 factors extend seed longevity in multiple plant species. New Phytologist (2021) Jul;231(2):679-694

Isabel Faus, R. Niñoles, V. Kesari & J. Gadea*.The ABCF3 Gene of Arabidopsis Is Functionally Linked with GCN1 but Not with GCN2 During Stress and Development, 2021. Plant Mol Biol Rep (2021). https://doi.org/10.1007/s11105-021-01283-w

Renard J, Niñoles R, Martínez-Almonacid I, Gayubas B, Mateos-Fernández R, Bissoli G, Bueso E, Serrano R*, Gadea J*. Identification of novel seed longevity genes related to oxidative stress and seed coat by genome-wide association studies and reverse genetics. Plan Cell and Environment 2020 Oct;43(10):2523-2539.

Isabel Faus, Regina Niñoles, Susana Tárraga, Jose Gadea*. Proteomic analysis of the ila2 mutant of Arabidopsis links translational regulation with photosynthesis, protein folding and ribosomal proteins. Acta Physiologiae Plantarum 2020 42(4)

Renard, Joan; Martínez-Almonacid, Irene; Sonntag, Annika; Molina, Isabel; Moya-Cuevas, José; Bissoli, Gaetano; Munoz-Bertomeu, Jesus; Faus, Isabel; Niñoles, Regina; Shigeto, Jun; Tsutsumi, Yuji; Gadea, Jose; Serrano, Ramon; Bueso, Eduardo*. Peroxidases regulate the polyphenolics spectrum in seed coats to increase seed longevity. Plan Cell and Environment, 2020 Feb;43(2):315-326.

Favaro MA, Molina MC, Roeschlin RA, Gadea J, Gariglio N, Marano MR*. Differen Responses in Mandarin Cultivars Uncover a Role of Cuticular Waxes in the Resistance to Citrus Canker, Phytopathology, 2020, Nov;110(11):1791-1801

de Luis B, Llopis-Lorente A, Rincón P, Gadea J, Sancenon F, Aznar E, Villalonga R, Murguía JR, Martínez-Máñez R*. An Interactive Model of Communication between Abiotic Nanodevices and Living Microorganisms. Angew Chem Int Ed Engl. 2019 doi: 10.1002/anie.201908867

Roeschlin RA, Uviedo F, García L, Molina MC, Favaro MA, Chiesa MA, Tasselli S, Franco-Zorrilla JM, Forment J, Gadea J*, Marano MR*. PthA4(AT) , a 7.5-repeats transcription activator-like (TAL) effector from Xanthomonas citri ssp. citri, triggers citrus canker resistance. Molecular Plant Pathology. 2019 Jul 5. doi:10.1111/mpp.12844.

Paula Llabata, Julia Richter, Isabel Faus, Karolina M. Slominska-Durdasiak, Lukas H. Zeh, Jose Gadea, Marie-Theres Hauser*. Involvement of the eIF2a kinase GCN2 in UV-B responses 2019 Frontiers in Plant Sciences, Nov 28;10:1492. doi: 10.3389/fpls.2019.01492.

Chiesa MA, Roeschlin RA, Favaro MA, Uviedo F, Campos-Beneyto L, D’Andrea R,Gadea J, Marano MR*. Plant responses underlying nonhost resistance of Citrus limon against Xanthomonas campestris pv. Campestris. Mol Plant Pathol. 2018 Sep 27.

Faus I, Niñoles R, Kesari V, Llabata P, Tam E, Nebauer SG, Santiago J, Hauser MT, Gadea J*. Arabidopsis ILITHYIA protein is necessary for proper chloroplast biogenesis and root development independent of eIF2α phosphorylation. Journal Plant Physiology. 2018 May – Jun;224-225:173-182.

Roeschlin RA, Favaro MA, Chiesa MA, Alemano S, Vojnov AA, Castagnaro AP, Filippone MP, Gmitter FG Jr, Gadea J*, Marano MR*. Resistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy-associated vacuolar processes. Mol Plant Pathol. 2017 Sep 20. doi: 10.1111/mpp.12489.

Amil-Ruiz F, Garrido-Gala J, Gadea J, Blanco-Portales R, Muñoz-Mérida A, Trelles O, de Los Santos B, Arroyo FT, Aguado-Puig A, Romero F, Mercado JÁ, Pliego-Alfaro F, Muñoz-Blanco J, Caballero JL*. Partial Activation of SA- and JA-Defensive Pathways in Strawberry upon Colletotrichum acutatum Interaction. Frontiers in Plant Sciences. 2016 Jul 15;7:1036

Faus I, Zabalza A, Santiago J, Nebauer SG, Royuela M, Serrano R, Gadea J*. Protein kinase GCN2 mediates responses to glyphosate in Arabidopsis. BMC Plant Biol. 2015 Jan 21;15:14. doi: 10.1186/s12870-014-0378-0.

Menacho-Márquez M, Rodríguez-Hernández CJ, Villaronga MÁ, Pérez-Valle J, Gadea J, Belandia B, Murguía JR*. eIF2 kinases mediate β-lapachone toxicity in yeast and human cancer cells. Cell Cycle. 2015;14(4):630-40. doi: 10.4161/15384101.2014.994904.

2015-2024

• Referencia: PID2022-139364OB-I00; IPs: José Gadea (UPV)

Título: Desvelando el impacto del ambiente sobre la longevidad de las semillas. Entidad financiadora: Ministerio de Ciencia. Convocatoria: Plan Nacional Proyectos de Excelencia. Fechas: 01/01/2023 – 31/12/2026. Cuantía: 175.000. Tipo de Participación: investigador principal

• Referencia: PAID-06-22; IP: Regina Niñoles (UPV)

• Referencia: PRE-HLB; IP: José Gadea (UPV)

Título: Preventing HLB epidemics for ensuring citrus survival in Europe. Entidad financiadora: Comunidad Europea Convocatoria: H2020 H2020-SFS-2018-2020 Fechas: 01/05/2019 – 31/04/2022 Cuantía financiada: 150.000 Tipo de Participación: investigador principal

• Referencia: PICT-2018-03051; IP: Maria Rosa Marano (IBR-U. Rosario)

Título: Efectores de patógenos bacterianos de cítricos: función y aplicación como herramienta en el control de enfermedades del cultivo.  Entidad financiadora: Agencia Nacional Argentina Convocatoria: PICT 2018 Fechas: 01/2018-12/2021 Cuantía: 39.000 Tipo de Participación: equipo investigador

• Referencia: RTC‐2017‐5912‐2; IP: José Gadea (UPV)

Título: ABOD: Biotecnología para generar fertilizantes duales sobre el sistema suelo-planta. Entidad financiadora: Ministerio de Ciencia e Innovación. Convocatoria: Retos de Colaboración. Fechas: 01/01/2018 – 31/03/2021. Cuantía: 66.000  Tipo de Participación: investigador principal

• Referencia: RTC‐2017‐5910‐2; IP: José Gadea (UPV)

Título: SEEDCOAT-BIO: Film-coating biológico de semillas: una nueva forma de fitomejora sostenible. Entidad financiadora: Ministerio de Ciencia e Innovación, Convocatoria: Retos de Colaboración. Fechas: 01/01/2018 – 31/05/2021; Cuantía: 150.000 Tipo de Participación: investigador principal

• Referencia: BIO2017-88898-P; IPs: José Gadea (UPV)

Título: Redes reguladoras de la longevidad de semillas que actúan a través de la permeabilidad de la cubierta, defensas antioxidantes y enzimas reparadoras. Entidad financiadora: Ministerio de Ciencia e Innovación. Convocatoria: Plan Nacional Proyectos de Excelencia. Fechas: 01/01/2017 – 31/12/2020. Cuantía: 193.000. Tipo de Participación: investigador principal

• Referencia: PICT-2016-1222 IP: Maria Rosa Marano (IBR-U. Rosario)

Título: Caracterización de las bases genéticas de la resistencia a la cancrosis de los cítricos mediada por un efector TAL PTHA4 truncado de una variante natural de Xanthomona citri subsp. Citri. Entidad financiadora: Agencia Nacional Argentina Convocatoria: PICT 2016. Fechas: 01/2016-12/2019. Cuantía: 35.000.Tipo de Participación: equipo investigador

• Referencia: BIO2014-52621-R; IP:Ramón Serrano (UPV)

Título: Regulacion del desarrollo de la cubierta de las semillas como herramienta para aumentar su longevidad; Entidad financiadora: Ministerio de Ciencia e Innovación; Convocatoria: Plan Nacional Retos de la Sociedad; Fechas: 01/01/2015 – 31/12/2017; Cuantía: 170.000: Tipo de Participación: equipo investigador

• Referencia: Prometeo II 2014/41. IP: Ramón Serrano (UPV)

Título: La homeostasis de cationes monovalentes (H+, K+, Na+) y el crecimiento y muerte celular. Entidad financiadora: Generalitat Valenciana. Conselleria de Educacion. Convocatoria: Prometeo. Fechas: 1/2014-12/2017. Cuantía 2014: 41.000.Tipo de Participación: equipo investigación

• Referencia: PICT-2013-0400 IP: Maria Rosa Marano, (IBR-U. Rosario)

Título: Identificación y caracterización funcional de factores de virulencia de Candidatus L. asiaticus, agente causal del Huanglongbing. Entidad financiadora: Agencia Nacional Argentina. Convocatoria: PICT 2013. Fechas: 01/2015-12/2017. Cuantía: 35.000.Tipo de Participación: equipo investigador

2015-2021

Renard Meseguer, Joan. Identification of Genes Related To Seed Longevity In Arabidopsis Thaliana Using Genomic Molecular Techniques. 15/06/21

Faus Ferrer, María Isabel. Caracterización Del Sistema Gcn En Plantas Mediante La Utilización De Mutantes De Pérdida De Función. 29/09/20

María Celeste Molina. Identificación de factores de virulencia de Candidatus Liberibacter asiaticus, agente causal del Huanglongbing (HLB) de los cítricos, mediante análisis funcional en sistemas heterólogos. 25/06/2021