Spotting the targets of the aposporous apomixis controller TGS1 in Paspalum notatum

PODIO, MARICEL; LEBLANC, OLIVIER; COLONO, CAROLINA; SIENA, LORENA; ORTIZ, JUAN PABLO; PESSINO, SILVINA

Praga

Conferencia; International Conference on Sexual Plant Reproduction; 2022

International Sexual Plant Reproduction Committee

Sexuality and apomixis are interconnected plant reproductive routes possibly behaving as polyphenic traits under the influence of the environment. In Paspalum notatum, an apomictic subtropical forage grass, one of their main apomixis controllers is TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1). The silencing of TGS1 induces a sexuality decline and the emergence of aposporous-like embryo sacs. In animal and plant models, TGS1 was characterized as a multifunctional gene expression regulator involved in the establishment of heterochromatin as well as the modulation of transcription and RNA processing. Our work here was aimed at identifying TGS1 targets in the Paspalum notatum floral transcriptome. First, we mined available RNA databases originated from florets of sexual and apomictic plants, which display a contrasting TGS1 representation, to identify differentially expressed mRNA splice variants and miRNAs. The role of TGS1 in the generation of these particular RNA processing products was investigated in antisense tgs1 sexual lines by using qPCR and in situ hybridization. We found that CHLOROPHYLL A-B BINDING PROTEIN 1B-21 (LHC Ib-21, a component of the chloroplast light harvesting complex), QUI-GON JINN (QGJ, encoding a MAP3K previously associated with apomixis) and miR2275 (a meiotic 24-nt phasi-RNAs producer) are direct or indirect TGS1 functional targets. Our results point to a coordinated control of signal transduction and siRNA machineries in the sexuality to apomixis transition.