Siena L.A. auteur aut IRD Michaud Caroline auteur aut IRD Colono C. auteur aut IRD Sol Vega M. auteur aut IRD Ortiz J.P.A. auteur aut IRD Pessino S.C. auteur aut IRD Leblanc Olivier auteur aut IRD text conferencePaper eng text/pdf reformatted digital access Paspalum notatum, a subtropical forage grass native to South America, has proven to be a fruitful model for studying apomixis in plants. Several genes associated with apomixis have been identified through genetic mapping and comparative mRNA analyses, including QUI-GON JINN (QGJ) encoding a MAPK3 protein of the YODA family. Interestingly, the downregulation of QGJ in P. notatum apomictic genotypes has been associated with a decrease in the number of unreduced (aposporous) embryo sacs. To disclose QGJ function during sexual development, we have undertaken its functional characterization in the model plant Arabidopsis thaliana using genetic and cellular approaches. The protein accumulation generated by GUS reporter lines indicated that QGJ is expressed during ovule development and accumulates in the L1 cell layer of the ovule primordium, but not in the placenta. QGJ is also expressed in degenerating megaspores, while functional megaspores completely lack signal. Finally, in developing seeds, the endosperm showed GUS accumulation, but the zygote and growing embryos were completely devoid of signal. Furthermore, qgj defective mutants led to reproductive alterations of the female development, in a manner reminiscent of apomixis. Furthermore, qgj mutants showed alterations during female meiosis, female gametophytic development and early seed development. These results indicate that QGJ is expressed during megasporogenesis and endosperm development, and suggest that its function is related with megaspore degeneration in the tetrad, gametophyte development and non-cell autonomous control of embryo development. specialized AMERIQUE DU SUD 076PHYBIO06 076AMEPLA04 International APOMIXIS 2025 Conference, 5., Montpellier (FRA), 2025/09/16-19 47 Leblanc Olivier ed. edt IRD Autran Daphné ed. edt IRD Marseille (FRA) IRD Montpellier DIADE 2025 https://www.documentation.ird.fr/hor/fdi:010096562 [F A010096557] https://www.documentation.ird.fr/hor/fdi:010096562 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2026-03/010096562.pdf IRD - Base Horizon / Pleins textes 2026-02-05 2026-03-05 fdi:010096562 fre