3D cellular morphometrics of ovule primordium development in Zea mays reveal differential division and growth dynamics specifying megaspore mother cell singleness

Ouedraogo Inès, Lartaud Marc, Baroux Célia, Mosca Gabriella, Delgado Luciana, Leblanc Olivier, Verdeil Jean-Luc, Conejero Geneviève, Autran Daphné. 2023. 3D cellular morphometrics of ovule primordium development in Zea mays reveal differential division and growth dynamics specifying megaspore mother cell singleness. Frontiers in Plant Science, 14:1174171, 17 p.

Url - jeu de données - Entrepôt autre : https://doi.org/10.5281/zenodo.7671594 / Url - jeu de données - Entrepôt autre : https://doi.org/10.5281/zenodo.7675365 / Url - jeu de données - Entrepôt autre : https://doi.org/10.5281/zenodo.7675409

Résumé : Introduction: Differentiation of spore mother cells marks the somatic-to-reproductive transition in higher plants. Spore mother cells are critical for fitness because they differentiate into gametes, leading to fertilization and seed formation. The female spore mother cell is called the megaspore mother cell (MMC) and is specified in the ovule primordium. The number of MMCs varies by species and genetic background, but in most cases, only a single mature MMC enters meiosis to form the embryo sac. Multiple candidate MMC precursor cells have been identified in both rice and Arabidopsis, so variability in MMC number is likely due to conserved early morphogenetic events. In Arabidopsis, the restriction of a single MMC per ovule, or MMC singleness, is determined by ovule geometry. To look for potential conservation of MMC ontogeny and specification mechanisms, we undertook a morphogenetic description of ovule primordium growth at cellular resolution in the model crop maize. Methods: We generated a collection of 48 three-dimensional (3D) ovule primordium images for five developmental stages, annotated for 11 cell types. Quantitative analysis of ovule and cell morphological descriptors allowed the reconstruction of a plausible developmental trajectory of the MMC and its neighbors. Results: The MMC is specified within a niche of enlarged, homogenous L2 cells, forming a pool of candidate archesporial (MMC progenitor) cells. A prevalent periclinal division of the uppermost central archesporial cell formed the apical MMC and the underlying cell, a presumptive stack cell. The MMC stopped dividing and expanded, acquiring an anisotropic, trapezoidal shape. By contrast, periclinal divisions continued in L2 neighbor cells, resulting in a single central MMC. Discussion: We propose a model where anisotropic ovule growth in maize drives L2 divisions and MMC elongation, coupling ovule geometry with MMC fate.

Mots-clés Agrovoc : Zea mays, ovule (plante), croissance, morphogénèse

Mots-clés libres : Ovule primordium, 3D morphometrics, Developmental atlas, Morphogenesis, Zea mays, Female germ cell, MMC specification

Classification Agris : F63 - Physiologie végétale - Reproduction
F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement européennes : European Commission

Agences de financement hors UE : Agence Nationale de la Recherche, Swiss National Science Foundation, Agropolis Fondation

Programme de financement européen : H2020

Projets sur financement : (FRA) Imagerie et modélisation de la croissance et de la plasticité des ovules chez les plantes, (FRA) Labex AGRO 2011-LBX-002, (FRA) Role et régulation de l'hétérochromatine au cours de la reproduction chez le maïs, et utilisation en amélioration des plantes.

Auteurs et affiliations

• Ouedraogo Inès, Université de Montpellier (FRA)
• Lartaud Marc, Université de Montpellier (FRA)
• Baroux Célia, UZH (CHE)
• Mosca Gabriella, UZH (CHE)
• Delgado Luciana, Universidad del Rosario (COL)
• Leblanc Olivier, Université de Montpellier (FRA)
• Verdeil Jean-Luc, CIRAD-BIOS-UMR AGAP (FRA)
• Conejero Geneviève, INRAE (FRA)
• Autran Daphné, Université de Montpellier (FRA) - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/607445/)

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