RESUMEN
Drought stress restricts crop productivity and exacerbates food shortages. The plant hormone, abscisic acid (ABA), has been shown to be a pivotal player in the regulation of drought tolerance and seed germination in plants. ABA accumulates under abiotic stresses to promote miR159 expression. miR159 is an ancient and conserved plant miRNA that plays diverse roles in plant development, seed germination, and drought response in Arabidopsis. Our previous studies demonstrated that miR159 regulates the vegetative phase change by repressing the ABI5 activation and thereafter preventing hyperactivation of miR156. However, whether the miR159-MYB33-ABI5 module plays a role in seed germination and drought response, and if so, how they interact genetically, remain largely unexplored. Here, we show that loss-of-function of miR159 (mir159ab) confers enhanced drought tolerance and hypersensitivity of seed germination to ABA. Genetic analyses demonstrated that loss-of-function mutation in the ABI5 gene suppresses the hypersensitivity of mir159ab to ABA, and the insensitivity of myb33 seeds to ABA treatment is ABI5 dependent. ABI5 functions downstream of MYB33 and miR159 in response to ABA. Therefore, our results uncover a new role for the miR159-MYB33-ABI5 module in the regulation of drought response and seed germination in plants.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , MicroARNs , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacología , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Regulación de la Expresión Génica de las Plantas/genética , Germinación/genética , MicroARNs/genética , MicroARNs/metabolismo , Semillas , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Vegetative development constitutes a critical phase in plant development, and it is regulated by an evolutionarily conserved miR156-SPL pathway. Previous studies have shown that miR159 acts to prevent the hyperactivation of miR156 to regulate the timing of vegetative phase change in Arabidopsis. However, whether miR159 integrates into the abscisic acid (ABA) signaling pathway to control vegetative phase change remains unexplored, since miR159 also plays an important regulatory role in ABA response. Here, we show that the expression of ABI5 (ABA INSENSITIVE5), a crucial regulator in the ABA signaling pathway, is significantly elevated in the loss-of-function mutant of miR159 (mir159ab). Loss of function in ABI5 (abi5) promotes juvenile-to-adult transition, whereas overexpression of ABI5 delays this transition under short-day conditions. Genetic analyses indicated that the effect of mir159ab on vegetative phase change is ABI5 dependent. Further analysis confirmed that MYB33, a major target of miR159, promotes the transcription of ABI5 by directly binding to its promoter. ABI5 functions upstream of miR156 to promote juvenile development by affecting the expression of genes in the miR156-SPL pathway. Therefore, our study uncovers a new role of ABI5 in vegetative development in plants, and implies a role of ABA signaling in vegetative development in Arabidopsis.