Seed abscission and fruit dehiscence required for seed dispersal rely on similar genetic networks

Seed dispersal is an essential trait that enables colonization of newfavorable habitats, ensuring species survival. In plants with dehiscentfruits, such asArabidopsis, seed dispersal depends on two processes:the separation of the fruit valves that protect the seeds (fruitdehiscence) and the detachment of the seeds from the funiculusconnectingthemtothe motherplant (seed abscission).Postprint (published version

Sequential action of FRUITFULL as modulator of the activity of the floral regulators SVP and SOC1

[EN] The role in flowering time of the MADS-box transcription factor FRUITFULL (FUL) has been proposed in many works. FUL has been connected to several flowering pathways as a target of the photoperiod, ambient temperature, and age pathways and it is has been shown to promote flowering in a partially redundant manner with SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). However, the position of FUL in these genetic networks, as well as the functional output of FUL activity during floral transition, remains unclear. In this work, a genetic approach has been undertaken to understand better the functional hierarchies involving FUL and other MADS-box factors with well established roles as floral integrators such as SOC1, SHORT VEGETATIVE PHASE (SVP) or FLOWERING LOCUS C (FLC). Our results suggest a prominent role of FUL in promoting reproductive transition when photoinductive signalling is suppressed by short-day conditions or by high levels of FLC expression, as in non-vernalized winter ecotypes. A model is proposed where the sequential formation of FUL–SVP and FUL–SOC1 heterodimers may mediate the vegetative and meristem identity transitions, counteracting the repressive effect of FLC and SVP on flowering.We thank Francisco Madueno and Jose Antonio Jarillo for critical reading of the manuscript and their helpful comments and suggestions. Our work was supported by grants BIO2009-09920 from the Spanish Ministerio de Ciencia e Innovacion and BIO2012-32902 from the Spanish Ministerio de Economia y Competitividad to CF. VB was supported by a doctoral fellowship of the Generalitat Valenciana.Balanzá Pérez, V.; Martinez-Fernandez, I.; Ferrandiz Maestre, C. (2014). Sequential action of FRUITFULL as modulator of the activity of the floral regulators SVP and SOC1. Journal of Experimental Botany. 65(4):1193-1203. https://doi.org/10.1093/jxb/ert482S1193120365

Identification of Players Controlling Meristem Arrest Downstream of the FRUITFULL-APETALA2 Pathway

[EN] The end of the reproductive phase in monocarpic plants is determined by a coordinated arrest of all active meristems, a process known as global proliferative arrest (GPA). GPA is linked to the correlative control exerted by developing seeds and, possibly, the establishment of strong source-sink relationships. It has been proposed that the meristems that undergo arrest at the end of the reproductive phase behave at the transcriptomic level as dormant meristems, with low mitotic activity and high expression of abscisic acid response genes. Meristem arrest is also controlled genetically. In Arabidopsis (Arabidopsis thaliana), the MADS-box transcription factor FRUITFULL induces GPA by directly repressing genes of the APETALA2 (AP2) clade. The AP2 genes maintain shoot apical meristem (SAM) activity in part by keeping WUSCHEL expression active, but the mechanisms downstream of this pathway remain elusive. To identify target genes, we performed a transcriptomic analysis, inducing AP2 activity in meristems close to arrest. Our results suggest that AP2 controls meristem arrest by repressing genes related to axillary bud dormancy in the SAM and negative regulators of cytokinin signaling. In addition, our analysis indicates that genes involved in the response to environmental signals also respond to AP2, suggesting that it could modulate the end of flowering by controlling responses to both endogenous and exogenous signals. Our results support the previous observation that at the end of the reproductive phase the arrested SAM behaves as a dormant meristem, and they strongly support AP2 as a master regulator of this process.This work was supported by the Spanish Ministerio de Economia, Industria y Competitividad/Fondo Europeo de Desarrollo Regional, European Union (grant no. BIO2015-64531-R to C.F.), the Spanish Ministerio de Ciencias, Investigacion y Universisdades/Agencia estatal de Investigacion/Fondo Europeo de Desarrollo Regional, European Union (grant no. RTI2018-099239-B-I00 to C.F.), Generalitat Valenciana (grant no. PROMETEU/2019/004 to C.F.), the National Council for Scientific and Technological Development (grant no. CNPq, 308832/2017-5 to M.A.F.), the National Institute of Science and Technology (grant no. 465480/2014-4 to M.A.F.), the Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (grant no. E-26/202.631/2019 to M.A.F.), and the European Union (grant no. FP7-PEOPLE-PIRSES-2009-247589 to C.F. and M.A.F.).Martínez-Fernández, I.; Menezes De Moura, S.; Alves-Ferreira, M.; Ferrandiz Maestre, C.; Balanzà, V. (2020). Identification of Players Controlling Meristem Arrest Downstream of the FRUITFULL-APETALA2 Pathway. Plant Physiology. 184(2):945-959. https://doi.org/10.1104/pp.20.00800S945959184

Genetic control of meristem arrest and life span in Arabidopsis by a FRUITFULL-APETALA2 pathway

Monocarpic plants have a single reproductive cycle in their lives, where life span is determined by the coordinated arrest of all meristems, or global proliferative arrest (GPA). The molecular bases for GPA and the signaling mechanisms involved are poorly understood, other than systemic cues from developing seeds of unknown nature. Here we uncover a genetic pathway regulating GPA in Arabidopsis that responds to age-dependent factors and acts in parallel to seed-derived signals. We show that FRUITFULL (FUL), a MADS-box gene involved in flowering and fruit development, has a key role in promoting meristem arrest, as GPA is delayed and fruit production is increased in ful mutants. FUL directly and negatively regulates APETALA2 expression in the shoot apical meristem and maintains the temporal expression of WUSCHEL which is an essential factor for meristem maintenance