PRECOCIOUS1 (POCO1), a mitochondrial pentatricopeptide repeat protein affects flowering time in Arabidopsis thaliana

Abstract

Flowering is a vital developmental shift in plants from vegetative to reproductive phase. The timing of this shift is regulated by various linked genetic pathways including environmental cues and internal regulation. Here we report a role for an Arabidopsis gene, AT1G15480, which encodes a P-class pentatricopeptide repeat (PPR) protein, affecting flowering time. We show that AT1G15480 is localized to mitochondria. An AT1G15480 T-DNA insertion line exhibits an early-flowering phenotype, which is quite a rare phenotype among PPR mutants. The early-flowering phenotype was observed under both long and short days compared with wild type plants. Genetic complementation confirmed the observed phenotype. We therefore named the PPR protein PRECOCIOUS1 (POCO1). poco1 plants showed lower respiration, ATP content and higher accumulation of superoxide. Importantly, the quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that the expression of FLOWERING LOCUS C (FLC), which is a key floral repressor, was strongly downregulated in the poco1. Likewise, the expression level of the FLC positive regulator ABSCISIC ACID-INSENSITIVE 5 (ABI5) was reduced in the poco1. Consistent with the qRT-PCR results, poco1 plants showed reduced sensitivity to abscisic acid compared with wild type with respect to primary root growth and days to flowering. Furthermore, the poco1 mutation enhances the sensitivity to drought stress. Further analysis showed that POCO1 affects mitochondrial RNA editing. Taken together, our data demonstrate a remarkable function of POCO1 in flowering time and the abscisic acid signalling pathway.

Two reproductive traits show contrasting genetic architectures in Plantago lanceolata

“…Yet, despite their potential importance, the genetic mechanisms underlying cytonuclear interactions remain obscure (Bock, Andrew, & Rieseberg, 2014;Budar & Roux, 2011;Roux et al, 2016;Soltani et al, 2016). A nuclear-encoded pentatricopeptide repeat (PPR) protein, POCO1, has been shown to regulate flowering time in A. thaliana via mitochondrial RNA editing (Emami & Kempken, 2019), suggesting one possible mechanism that could underlie the cytonuclear interaction we have observed.…”

Transcriptomic analysis of poco1, a mitochondrial pentatricopeptide repeat protein mutant in Arabidopsis thaliana

“…Biological process GO terms related to biotic stresses and defense response such as "glycosyl compound biosynthesis," "response to biotic stimulus," "glycosinolate biosynthetic," and "sulfur compound biosynthesis process" were over-represented in the up-regulated genes of preinflorescence-inflorescence (69 genes) (Additional file 2: Figure S1). The biological process GO terms "cell redox homeostasis," "cellular homeostasis," and "electron transport chain" were enriched in the down-regulated genes of pre-inflorescence-inflorescence (80 genes) (Additional file 2: Figure S1), which may be related to the higher generation of ROS in poco1 [27]. GO enrichment of the up-and down-regulated genes of inflorescence-flowering (338 and 537 genes respectively) (Additional file 2: Figure S1) showed that various stress response-related processes are highly over-represented, which may indicate that different stresses allocate some identical pathways.…”

“…A recent study showed that poco1 carries a T-DNA insertion and was identified to be a homozygous T-DNA insertion mutant [27]. No POCO1 transcript could be identified in poco1 by RT-PCR.…”

“…poco1 inactivates ABA signaling and response A recent study revealed that poco1 plants showed an insensitive phenotype to ABA regarding the primary root growth and flowering time. The study showed that ABI5, which acts at the core of ABA signaling, is downregulated in poco1 plants [27]. To enhance our understanding, the focus was laid on other factors associated with ABA signaling and response were searched in the differentially expressed genes in the RNA-seq results.…”

“…In a recent study, we showed that a T-DNA insertional mutation in a mitochondrial PPR protein, POCO1, led to an early floral transition [27]. PPR proteins comprise a large family in land plants with 450 distinct members in A. thaliana and are involved in the post-transcriptional gene expression such as translation, splicing, editing, and stability of transcripts in organelles [28,29].…”