Disclosing the Molecular Link between Apospory and Diplospory

GARBUS INGRID; PODIO MARICEL; ECHENIQUE VIVIANA; PESSINO SILVINA

Workshop; VII Ciclo de Seminarios sobre avances en la Caracterización Genética y Molecular de la APOMIXIS; 2020

Gametophytic apomixis forms seeds with clonal embryos identical to the motherplant through two different mechanisms, namely apospory and diplospory, both of theminvolving the formation of non-reduced megagametophytes within the ovule. These nonreduced embryo sacs are originated from companion nucellar cells (apospory) or the megaspore mother cell, after absence/failure of meiosis (diplospory). In both paths the non-reduced egg cells produce embryos through parthenogenesis. Our hypothesis here wasthat, at least for some candidate genes, apomeiosis and parthenogenesis associate, respectively,with contrasting or identical representation patterns in aposporous vs. diplosporousdifferential mRNA expression comparisons. The rationale supporting this propositionis that in aposporous and diplosporous plants apomeiosis might involve somecommon genes under an opposite spatio-temporal regulation pattern (OE transcripts),while parthenogenesis should be identically activated in both reproductive types (IE candidates).We compared two sets of Roche/454 sequences differentially expressed in reproductiveorgans of sexual vs. apomictic plants of Paspalum notatum (aposporous) and Eragrostiscurvula (diplosporous) from pre-meiosis to anthesis, to identify OE and IE transcripts.Then, the selected sequences were investigated in TruSeq/Hiseq Illumina RNAfloral libraries constructed at different reproductive stages. We found 89 opposite expressiontranscripts exclusively represented at pre-meiosis and 66 equal expression transcriptsoccurring at anthesis only. These candidate genes were used to produce String interactionnetworks with others previously related with apomeiosis and parthenogenesis, and theirlocation is being mapped within the Paspalum and Eragrostis genomic ACL (apomixis controlling loci). Functional analysis of selected sequences is at work.