RESUMO
The plant hormones salicylic acid (SA) and jasmonic acid (JA) regulate defense mechanisms capable of overcoming different plant stress conditions and constitute distinct but interconnected signaling pathways. Interestingly, several other molecules are reported to trigger stress-specific defense responses to biotic and abiotic stresses. In this study, we investigated the effect of 14 elicitors against diverse but pivotal types of abiotic (drought) and biotic (the chewing insect Ascia monuste, the hemibiotrophic bacterium Pseudomonas syringae DC 3000 and the necrotrophic fungus Alternaria alternata) stresses on broccoli and Arabidopsis. Among the main findings, broccoli pre-treated with SA and chitosan showed the highest drought stress recovery in a dose-dependent manner. Several molecules led to increased drought tolerance over a period of three weeks. The enhanced drought tolerance after triggering the SA pathway was associated with stomata control. Moreover, methyl jasmonate (MeJA) reduced A. monuste insect development and plant damage, but unexpectedly, other elicitors increased both parameters. GUS reporter assays indicated expression of the SA-dependent PR1 gene in plants treated with nine elicitors, whereas the JA-dependent LOX2 gene was only expressed upon MeJA treatment. Overall, elicitors capable of tackling drought and biotrophic pathogens mainly triggered the SA pathway, but adversely also induced systemic susceptibility to chewing insects. These findings provide directions for potential future in-depth characterization and utilization of elicitors and induced resistance in plant protection.
Assuntos
Arabidopsis/imunologia , Brassica/imunologia , Resistência à Doença , Doenças das Plantas/imunologia , Acetatos/metabolismo , Alternaria/patogenicidade , Animais , Arabidopsis/microbiologia , Arabidopsis/parasitologia , Brassica/microbiologia , Brassica/parasitologia , Borboletas/patogenicidade , Ciclopentanos/metabolismo , Secas , Regulação da Expressão Gênica de Plantas/imunologia , Oxilipinas/metabolismo , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Proteínas de Plantas/metabolismo , Pseudomonas syringae/patogenicidade , Ácido Salicílico/metabolismoRESUMO
UNLABELLED: Cruciferous plants are important edible vegetables widely consumed around the world, including cabbage, cauli-flower and broccoli. The main disease that affects crucifer plants is black rot, caused by Xanthomonas campestris pv. campestris (Xcc). In order to better understand this specific plant-pathogen interaction, proteins responsive to Xcc infection in resistant (União) and susceptible (Kenzan) Brassica oleracea cultivars were investigated by 2-DE followed by mass spectrometry. A total of 47 variable spots were identified and revealed that in the susceptible interaction there is a clear reduction in the abundance of proteins involved in energetic metabolism and defense. It was interesting to observe that in the resistant interaction, these proteins showed an opposite behavior. Based on our results, we conclude that resistance is correlated with the ability of the plant to keep sufficient photosynthesis metabolism activity to provide energy supplies necessary for an active defense. As a follow-up study, qRT-PCR analysis of selected genes was performed and revealed that most genes showed an up-regulation trend from 5 to 15days after inoculation (DAI), showing highest transcript levels at 15DAI. These results revealed the gradual accumulation of transcripts providing a more detailed view of the changes occurring during different stages of the plant-pathogen interaction. BIOLOGICAL SIGNIFICANCE: In this study we have compared cultivars of Brassica oleracea (cabbage), susceptible and resistant to black rot, by using the classical 2-DE approach. We have found that resistance is correlated with the ability of the plant to keep sufficient photosynthesis metabolism activity to provide energy supplies necessary for an active defense.
Assuntos
Brassica/microbiologia , Interações Hospedeiro-Patógeno/imunologia , Xanthomonas campestris/fisiologia , Brassica/química , Brassica/imunologia , Brassica/metabolismo , Eletroforese em Gel Bidimensional , Metabolismo Energético , Espectrometria de Massas , Fotossíntese , Proteômica/métodos , Regulação para Cima , Xanthomonas campestris/patogenicidadeRESUMO
Brassica crops infected by Plasmodiophora brassicae can produce root galls (clubroots) and be prevented from growing normally. To understand the series of changes that occur in the host root during root gall production, the resistance character of 21 Chinese cabbage lines were identified and then resistant and susceptible lines were used for infection observation. Hydroponic technology system was used for plants growing, and the infection process of P. brassicae in the roots of resistant and susceptible Chinese cabbage was examined based on morphology and microscopic characteristics using micoscope. In susceptible Chinese cabbage, the root hair infection stage occurred over approximately 7 days after inoculation, the cortical infection happened over approximatly 14 days after inoculation, and clubroots formed in approximately 30 days after inoculation. However, in resistant Chinese cabbage, the pathogen could be prevented and maintained in the root hair infection stage. This research provides a foundation for the subsequent studies of cabbage resistance of P. brassicae.