RESUMO
Enhancing carbohydrate export from source to sink tissues is considered to be a realistic approach for improving photosynthetic efficiency and crop yield. The rice sucrose transporters OsSUT1, OsSWEET11a and OsSWEET14 contribute to sucrose phloem loading and seed filling. Crucially, Xanthomonas oryzae pv. oryzae (Xoo) infection in rice enhances the expression of OsSWEET11a and OsSWEET14 genes, and causes leaf blight. Here we show that co-overexpression of OsSUT1, OsSWEET11a and OsSWEET14 in rice reduced sucrose synthesis and transport leading to lower growth and yield but reduced susceptibility to Xoo relative to controls. The immunity-related hypersensitive response (HR) was enhanced in the transformed lines as indicated by the increased expression of defence genes, higher salicylic acid content and presence of HR lesions on the leaves. The results suggest that the increased expression of OsSWEET11a and OsSWEET14 in rice is perceived as a pathogen (Xoo) attack that triggers HR and results in constitutive activation of plant defences that are related to the signalling pathways of pathogen starvation. These findings provide a mechanistic basis for the trade-off between plant growth and immunity because decreased susceptibility against Xoo compromised plant growth and yield.
Assuntos
Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras , Oryza , Doenças das Plantas , Imunidade Vegetal , Proteínas de Plantas , Plantas Geneticamente Modificadas , Ácido Salicílico , Sacarose , Xanthomonas , Oryza/microbiologia , Oryza/genética , Oryza/imunologia , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Xanthomonas/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Sacarose/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Membrana Transportadoras/genética , Ácido Salicílico/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/imunologiaRESUMO
Gibberellins (GA) are diterpenoids that are categorized as one of main hormones that promote major developmental responses such as germination and stem elongation in plants. DELLA proteins act as the key repressors of GA responses. They interact with hundreds of different proteins. While the functioning of DELLA as transcriptional coactivators has also been reported earlier, the actual mechanism still remains elusive. One recent report describes interaction of DELLA with Mediator subunit MED15 as one of the mechanisms contributing to its transcription activation capability (Hernández-García et al. 2024). Interestingly, this mechanism of DELLA-MED15 module-mediated transcription regulation seems to be very ancient conserved from bryophyte Marchantia polymorpha to dicot Arabidopsis thaliana.