RESUMO
KEY MESSAGE: Transgenic rice overexpressing PLCP attenuated the virulence of Xanthomonas oryzae pv. oryzae through extensive activation of transduction signal and transcription activities that orchestrate downstream responses including the biosynthesis of secondary metabolites and up-regulation of several pathogenesis-related proteins. High-throughput transcriptome investigations of plant immunity highlight the complexity of gene networks leading to incompatible interaction with the pathogen. Accumulating findings implicate papain-like cysteine proteases (PLCPs) as a central hub in plant defense. While diverse roles of PLCPs in different pathosystems have become more evident, information on gene networks and signaling pathways necessary to orchestrate downstream responses are lacking. To understand the biological significance of cysteine protease against Xanthomonas oryzae pv. oryzae, PLCP overexpression and knockout rice lines were generated. The pathogenicity test revealed the attenuation of Xanthomonas oryzae pv. oryzae race K3a virulence in transgenic lines which is ascribed to high hydrogen peroxide and free salicylic acid accumulation. Next-generation sequencing of RNA from transgenic and wild-type plants identified 1597 combined differentially expressed genes, 1269 of which were exclusively regulated in the transgenic libraries. It was found that PLCP aids rice to circumvent infection through the extensive activation of transduction signal and transcription factors that orchestrate downstream responses, including up-regulation of multiple pathogenesis-related proteins and biosynthesis of secondary metabolites.
Assuntos
Cisteína Endopeptidases/metabolismo , Resistência à Doença/genética , Oryza/enzimologia , Oryza/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Xanthomonas/patogenicidade , Cisteína Endopeptidases/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/imunologia , Técnicas de Inativação de Genes , Ontologia Genética , Genoma de Planta , Sequenciamento de Nucleotídeos em Larga Escala , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/imunologia , Peróxido de Hidrogênio/metabolismo , Oryza/genética , Oryza/imunologia , Doenças das Plantas/imunologia , Plantas Geneticamente Modificadas , Mapeamento de Interação de Proteínas , Interferência de RNA , RNA-Seq , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Transcriptoma , Regulação para Cima , VirulênciaRESUMO
UDP-glucose 4-epimerase (UGE) catalyzes the reversible conversion of UDP-glucose to UDP-galactose. To understand the biological function of UGE from Brassica rapa, the gene BrUGE1 was cloned and introduced into the genome of wild type rice 'Gopum' using the Agrobacterium-mediated transformation method. Four lines which carried a single copy gene were selected and forwarded to T3 generation. Agronomic traits evaluation of the transgenic T3 lines (CB01, CB03, and CB06) under optimal field conditions revealed enriched biomass production particularly in panicle length, number of productive tillers, number of spikelets per panicle, and filled spikelets. These remarkably improved agronomic traits were ascribed to a higher photosynthetic rate complemented with higher CO2 assimilation. Transcripts of BrUGE1 in transgenic lines continuously accumulated at higher levels after the 20% PEG6000 treatment, implying its probable role in drought stress regulation. This was paralleled by rapid accumulation of soluble sugars which act as osmoprotectants, leading to delayed leaf rolling and drying. Our findings suggest the potential of BrUGE1 in improving rice growth performance under optimal and water deficit conditions.
