Biology subjects

Micol-Ponce, R.

Publications and source records attributed to Micol-Ponce, R..

4 recordsLinked to original sources

bioRxiv2024

CXIP4 depletion causes early lethality and pre-mRNA missplicing in Arabidopsis

Zinc knuckle (ZCCHC) motif-containing proteins are present in unicellular and multicellular eukaryotes and most ZCCHC proteins with known functions participate in the metabolism of various classes of RNA, such as mRNAs, ribosomal RNAs, and microRNAs. The Arabidopsis (Arabidopsis thaliana) genome encodes 69 ZCCHC-containing proteins, but the functions of most remain unclear. One of these proteins is CAX-INTERACTING PROTEIN 4 (CXIP4), which has been classified as a PTHR31437 family member, along with human SREK1-interacting protein 1 (SREK1IP1), which is thought to function in pre-mRNA splicing and RNA methylation. Metazoan SREK1IP1-like and plant CXIP4-like proteins only share a ZCCHC motif, and their functions remain almost entirely unknown. We studied two loss-of-function alleles of Arabidopsis CXIP4, the first mutations in PTHR31437 family genes described to date: cxip4-1 is likely null and shows early lethality, and cxip4-2 is hypomorphic and viable, with pleiotropic morphological defects. The cxip4-2 mutant exhibited deregulation of defense genes and upregulation of transcription factor encoding genes, some of which might explain its developmental defects. This mutant also exhibited increased intron retention events, and the specific functions of misspliced genes, such as those involved in "gene silencing by DNA methylation" and "mRNA polyadenylation factor" suggest that CXIP4 has additional functions. The CXIP4 protein localizes to the nucleus in a pattern resembling nuclear speckles, which are rich in splicing factors. Therefore, CXIP4 is required for plant survival and proper development, and mRNA maturation.

plant biology↗

bioRxiv2023

Cross-kingdom conservation of Arabidopsis RPS24 function in 18S rRNA maturation

All 81 ribosomal proteins (RPs) that form the Arabidopsis (Arabidopsis thaliana) 80S ribosome are encoded by several paralogous genes. For example, the nearly identical RPS24A and RPS24B proteins are encoded by RPS24A and RPS24B, respectively. Here we explored the functions of RPS24A and RPS24B in Arabidopsis. Their encoding genes exhibit combined haploinsufficiency, as at least two wild-type copies of either RPS24A or RPS24B are required for plant viability and at least three are required for normal plant development. Loss-of-function of either gene caused a pointed-leaf phenotype, a typical phenotype of null or hypomorphic recessive alleles of genes encoding ribosome biogenesis factors (RBFs) or RPs. We also found that RPS24A and RPS24B act as RBFs during early stages of 18S ribosomal RNA (rRNA) maturation, as loss of RPS24A or RPS24B function reduced the 18S/25S rRNA ratio. An RPS24B-GFP fusion protein predominantly localized to the nucleolus, as expected. The rps24b-2 mutation strengthened the phenotypes of the RBF mutants mRNA transporter4-2 and small organ4-3, which are defective in 5.8S rRNA maturation. This synergistic interaction might be an effect of increased 45S rDNA transcription, which we also observed in the rps24 mutants. Therefore, the Arabidopsis RPS24 proteins act as RBFs during 18S rRNA maturation, like their human and yeast putative orthologs. Only two plant RPs were previously shown to act not only as structural components of the ribosome but also as RBFs. We provide evidence that RPS24 proteins also regulate 45S rDNA transcription, which has not been described for their yeast or human orthologs.

plant biology↗

bioRxiv2022

Various tomato cultivars display contrasted morphological and molecular responses to a heat wave.

Climate change is one of the biggest threats that human society currently needs to face. Heat waves associated with global warming negatively affect plant growth and development and will increase in frequency. Tomato is one of the most produced and consumed fruit in the world but remarkable yield losses occur every year due to the sensitivity of many cultivars to heat stress. New insights into how tomato plants are responding to heat waves will contribute to the development of new cultivars with high yields under harsh temperature conditions. In this study, the analysis of microsporogenesis and pollen germination rate of eleven tomato cultivars after exposure to a simulated heat wave revealed differences between genotypes. The transcriptome of floral buds at two developmental stages of five cultivars selected based on their pollen germination tolerance or sensitivity, revealed common and specific molecular responses implemented by tomato cultivars to cope with heat waves. These data provide valuable insights into the underlying molecular adaptation of floral buds to heat stress and will contribute to the development of future climate resilient tomato varieties.

plant biology↗

bioRxiv2021

Tomato CRABS CLAW paralogues interact with chromatin remodelling factors to mediate carpel development and floral determinacy

CRABS CLAW (CRC) orthologues play a crucial role in floral meristem (FM) determinacy and gynoecium formation across angiosperms, key developmental processes for ensuring successful plant reproduction and crop production. Here, we revealed that the incomplete penetrance and variable expressivity of the carpel-inside-carpel phenotype observed in flowers of the tomato fruit iterative growth (fig) mutant is due to a lack of function of a homologue of the CRC gene, Solanum lycopersicum CRCa (SlCRCa). Likewise, a comprehensive functional analysis of SlCRCa and SlCRCb paralogues, including Arabidopsis complementation experiments, allowed us to propose that they operate as positive regulators of FM determinacy by acting in a compensatory and partially redundant manner to safeguard the proper formation of flowers and fruits. Furthermore, we provide the first evidence for the role of putative CRC orthologues as members of the chromatin remodelling complex that terminates floral stem cell activity by repressing WUSCHEL expression.

developmental biology↗