RESUMEN
The submergence-induced hypoxic condition negatively affects the plant growth and development, and causes early onset of senescence. Hypoxia alters the expression of a number of microRNAs (miRNAs). However, the molecular function of submergence stress-induced miRNAs in physiological or developmental changes and recovery remains poorly understood. Here, we show that miR775 is an Arabidopsis thaliana-specific young and unique miRNA that possibly evolved non-canonically. miR775 post-transcriptionally regulates GALACTOSYLTRANSFERASE 9 (GALT9) and their expression is inversely affected at 24â h of complete submergence stress. The overexpression of miR775 (miR775-Oe) confers enhanced recovery from submergence stress and reduced accumulation of RBOHD and ROS, in contrast to wild-type and MIM775 Arabidopsis shoot. A similar recovery phenotype in the galt9 mutant indicates the role of the miR775-GALT9 module in post-submergence recovery. We predicted that Golgi-localized GALT9 is potentially involved in protein glycosylation. The altered expression of senescence-associated genes (SAG12, SAG29 and ORE1), ethylene signalling (EIN2 and EIN3) and abscisic acid (ABA) biosynthesis (NCED3) pathway genes occurs in miR775-Oe, galt9 and MIM775 plants. Thus, our results indicate the role for the miR775-GALT9 module in post-submergence recovery through a crosstalk between the ethylene signalling and ABA biosynthesis pathways.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Etilenos/farmacología , Galactosiltransferasas/metabolismo , MicroARNs/metabolismo , Senescencia de la Planta/efectos de los fármacos , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Sitios de Unión , Cisteína Endopeptidasas/genética , Cisteína Endopeptidasas/metabolismo , Dioxigenasas/genética , Dioxigenasas/metabolismo , Galactosiltransferasas/genética , Aparato de Golgi/metabolismo , MicroARNs/química , MicroARNs/genética , NADPH Oxidasas/genética , NADPH Oxidasas/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Transducción de Señal/genética , Estrés FisiológicoRESUMEN
MicroRNAs (miRNAs), a class of single-stranded non-coding RNA of 20-24 nucleotides, regulate gene expression by target gene transcript cleavage or translation inhibition. The phytohormone auxin is a crucial regulator of almost every process involved in plant growth and development. Several studies have demonstrated the involvement of miRNA(s) in the regulation of the auxin signaling pathway and plant development. However, very few studies have identified the auxin-mediated regulation of miRNA(s). In this study, we reveal the detailed mechanism of auxin-mediated regulation of the cell wall-related miR775- Galactosyl transferase (GalT) module, which plays an important role in root growth in Arabidopsis thaliana. We also showed two interdependent mechanisms by which miR775 regulates root growth: miR775-GalT and light-mediated sucrose-dependent pathways. Treatment of GUS reporter lines with Indole Acetic Acid (IAA), sucrose, and light apparently enhanced the abundance of miR775 in root tissue. miR775 overexpressing (miR775OX) lines showed changes in root architecture, including increased primary root growth and root hair, by targeting GalT. miR775OX lines also showed tolerance toward low Pi. These results provide new insights into the auxin regulation of cell wall-related miR775 and suggest its significant role in plant root growth and development by modifying the cell wall.