Expression analysis of chitinase upon challenge inoculation to Alternaria wounding and defense inducers in Brassica juncea (original) (raw)
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Alternaria blight is one among the serious diseases of Brassica juncea causing up to 45-58% loss in the yield with no proven source of transferable resistance in any of the hosts. The plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are major players in the regulation of signaling networks that are involved in induced defense responses against pathogens and insects. In order to develop resistance thoughtful information of defense mechanism in terms of defense signaling molecules involved and defense genes induced during the plant-pathogen interaction need to be understood at the molecular level. In the present study, Brassica juncea (Varuna) was taken for studying expression analysis of important defense genes with SA, JA and in vitro fungal infection as three separate treatments. We found that chitinase and thionin transcript levels were elevated in mustard leaves upon treatment with JA and during infection with necrotrophic fungal pathogen Alternaria brassicae. Conversely expression levels of PR1 and NPR1 were induced exclusively upon SA treatment. They were not induced either by JA or after fungal infection. These results clearly indicate existence of two separate hormone dependent pathways i.e. SA and JA in Brassica juncea similar to Arabidopsis thaliana reported earlier [1]. Glucanase expression was also seen during SA treatment although some expression was also seen by JA treatment.
Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression, 1995
Complementary and genomic DNAs coding for a Brassica napus chitinase have been cloned and sequenced. The genomic DNA contains one intron and encodes a 322-amino acid basic chitinase with a 20-amino acid N-terminal signal peptide followed by a 40-amino acid cysteine-rich domain, linked by a hinge region to the main domain of the enzyme. The sequence of the cDNAs is identical to the exon sequence deduced from the genomic DNA. A probe derived from this gene identified a 1.2-kb transcript present in high amount in roots, moderate in floral tissues and low in stems and leaves. The synthesis of these transcripts is regulated during development and is induced in roots by wounding and ethephon. This type of chitinase is encoded by two sequences in Brassica napus, as shown either by Southern hybridizations or by genomic amplification and sequencing using the polymerase chain reaction. These genes are homologous to one sequence found in the Brassica oleracea genome.
Developmental and Pathogen-Induced Activation of the Arabidopsis Acidic Chitinase Promoter
The Plant Cell, 1991
Expression of the Arabidopsis acidic chitinase promoter was investigated during plant development and in response to inoculation with fungal pathogens. A chimeric gene composed of 1129 bp of 5' upstream sequence from the acidic chitinase gene was fused to the 8-glucuronidase (GUS) coding region and used to transform Arabidopsis and tomato. Promoter activity was monitored by histochemical and quantitative assays of GUS activity. In healthy transgenic plants, the acidic chitinase promoter activity was restricted to roots, leaf vascular tissue, hydathodes, guard cells, and anthers, whereas GUS expression was induced in mesophyll cells surrounding lesions caused by Rhizoctonia solani infection of transgenic Arabidopsis. In transgenic tomato plants, GUS expression was induced around necrotic lesions caused by Alternaria solani and Phytophthora infestam. Expression of the acidic chitinase promoter-GUS transgene was weakly induced by infiltrating leaves with salicylic acid. Analysis of a series of 5' deletions of the acidic chitinase promoter in Arabidopsis indicated that the proximal 192 bp from the transcription initiation site was sufficient to establish both the constitutive and induced pattern of expression. Elements further upstream were involved in quantitative expression of the gene. The location of a negative regulatory element was indicated between -384 and -590 and positive regulatory elements between -1 129 and -590.
Plant Molecular Biology Reporter, 2010
Canola (Brassica napus L.) is an agriculturally and economically important crop in Canada, and its growth and yield are frequently influenced by fungal pathogens. Sclerotinia sclerotiorum is among those fungal pathogens and causes stem rot disease in B. napus whereas it has been reported that Brassica carinata is moderately tolerant to S. sclerotiorum. Jasmonic acid/ethylene (JA/ET) and salicylic acid (SA) are phytohormones that are known to be involved in plant disease responses. To investigate the defense signaling cascades involved in the interaction of B. napus and B. carinata with S. sclerotiorum, we examined the expression of five orthologs of B. napus genes involved in JA/ET or SA signaling pathways using quantitative RT-PCR. Our results indicated that there are differences in the timing of JA/ET and SA signaling pathways between B. napus and B. carinata. Our results in these two Brassica species also support previous observations that necrotrophic pathogens trigger JA/ET signaling in response to infection. Finally, we observed that transgenic canola expressing 1aminocyclopropane-1-carboxylate-deaminase producing low levels of ET was relatively more susceptible to S. sclerotiorum than its wild-type counterpart, suggesting that ET inhibits S. sclerotiorum-induced symptom development. Keywords Brassica. Sclerotinia sclerotiorum. Signaling pathway (ET), salicylic acid (SA), or reactive oxygen species (Kunkel and Brooks 2002). Signaling pathways, mediated by JA/ET and SA, are important components of plant defense systems (Dong 1998; Feys and Parker 2000; Martinez et al. 2001; McDowell and Dangl 2000). They are regulated and can act independently, synergistically, or antagonistically, which depends on the system between host/pathogens and are discussed below (Glazebrook 2005; Kachroo and Kachroo 2007). JA and its derivate methyl jasmonate (MeJA) are signaling molecules important for initiating and/or maintaining developmental processes and defense responses in various plants (Clarke et al. 2001; van der Fits et al. 2000). In Arabidopsis, as revealed by microarray analysis, five out Both Muhammad Rahman and Yue Liang contributed equally.
Developmental and Pathogen-lnduced Activation of the Arabidopsis Acidic Chitinase Promoter
1991
Expression of the Arabidopsis acidic chitinase promoter was investigated during plant development and in response to inoculation with fungal pathogens. A chimeric gene composed of 1129 bp of 5' upstream sequence from the acidic chitinase gene was fused to the 8-glucuronidase (GUS) coding region and used to transform Arabidopsis and tomato. Promoter activity was monitored by histochemical and quantitative assays of GUS activity. In healthy transgenic plants, the acidic chitinase promoter activity was restricted to roots, leaf vascular tissue, hydathodes, guard cells, and anthers, whereas GUS expression was induced in mesophyll cells surrounding lesions caused by Rhizoctonia solani infection of transgenic Arabidopsis. In transgenic tomato plants, GUS expression was induced around necrotic lesions caused by Alternaria solani and Phytophthora infestam. Expression of the acidic chitinase promoter-GUS transgene was weakly induced by infiltrating leaves with salicylic acid. Analysis of a series of 5' deletions of the acidic chitinase promoter in Arabidopsis indicated that the proximal 192 bp from the transcription initiation site was sufficient to establish both the constitutive and induced pattern of expression. Elements further upstream were involved in quantitative expression of the gene. The location of a negative regulatory element was indicated between -384 and -590 and positive regulatory elements between -1 129 and -590.
Tobacco-expressed Brassica juncea chitinase BjCHI1 shows antifungal activity in vitro
Plant molecular biology, 2002
We have previously isolated a Brassica juncea cDNA encoding BjCHI1, a novel chitinase with two chitin-binding domains, and have shown that its mRNA is induced by wounding and methyl jasmonate treatment (K.-J. Zhao and M.-L. Chye, Plant Mol. Biol. 40 (1999) 1009-1018). By the presence of two chitin-binding domains, BjCHI1 resembles the precursor of UDA (Urtica dioica agglutinin) but, unlike UDA, BjCHI1 retains its chitinase catalytic domain after post-translational processing. Here, we indicate the role of BjCHI1 in plant defense by demonstrating its mRNA induction upon Aspergillus niger infection or caterpillar Pieris rapae (L.) feeding. To further investigate the biological properties of BjCHI1, we transformed tobacco with a construct expressing the BjCHI1 cDNA from the CaMV 35S promoter. Subsequently, we purified BjCHI1 from the resultant transgenic Ro plants using a regenerated chitin column followed by fast protein liquid chromatography (FPLC). Also, the significance of the seco...
Plant Physiology, 2003
All tested accessions of Arabidopsis are resistant to the fungal pathogen Alternaria brassicicola. Resistance is compromised by pad3 or coi1 mutations, suggesting that it requires the Arabidopsis phytoalexin camalexin and jasmonic acid (JA)dependent signaling, respectively. This contrasts with most well-studied Arabidopsis pathogens, which are controlled by salicylic acid-dependent responses and do not benefit from absence of camalexin or JA. Here, mutants with defects in camalexin synthesis (pad1, pad2, pad3, and pad5) or in JA signaling (pad1, coi1) were found to be more susceptible than wild type. Mutants with defects in salicylic acid (pad4 and sid2) or ethylene (ein2) signaling remained resistant. Plant responses to A. brassicicola were characterized using expression profiling. Plants showed dramatic gene expression changes within 12 h, persisting at 24 and 36 h. Wild-type and pad3 plants responded similarly, suggesting that pad3 does not have a major effect on signaling. The response of coi1 plants was quite different. Of the 645 genes induced by A. brassicicola in wild-type and pad3 plants, 265 required COI1 for full expression. It is likely that some of the COI1-dependent genes are important for resistance to A. brassicicola. Responses to A. brassicicola were compared with responses to Pseudomonas syringae infection. Despite the fact that these pathogens are limited by different defense responses, approximately 50% of the induced genes were induced in response to both pathogens. Among these, requirements for COI1 were consistent after infection by either pathogen, suggesting that the regulatory effect of COI1 is similar regardless of the initial stimulus. ; fax 858 -350 -6306.
Journal of Experimental Botany, 2008
Brassica juncea BjCHI1 is a plant chitinase with two chitin-binding domains. Its expression, induced in response to wounding, methyl jasmonate treatment, Aspergillus niger infection, and caterpillar Pieris rapae feeding, suggests that it plays a role in defence. In this study, to investigate the potential of using BjCHI1 in agriculture, Pichia-expressed BjCHI1 and its deletion derivatives that lack one or both chitin-binding domains were tested against phytopathogenic fungi and bacteria. Transplastomic tobacco expressing BjCHI1 was also generated and its extracts assessed. In radial growth-inhibition assays, BjCHI1 and its derivative with one chitin-binding domain showed anti-fungal activities against phytopathogens, Colletotrichum truncatum, C. acutatum, Botrytis cinerea, and Ascochyta rabiei. BjCHI1 also inhibited spore germination of C. truncatum. Furthermore, BjCHI1, but not its derivatives lacking one or both domains, inhibited the growth of Gram-negative bacteria (Escherichia coli, Ralstonia solanacearum, Pseudomonas aeruginosa) more effectively than Gram-positive bacteria (Micrococcus luteus and Bacillus megaterium), indicating that the duplicated chitin-binding domain, uncommon in chitinases, is essential for bacterial agglutination. Galactose, glucose, and lactose relieved agglutination, suggesting that BjCHI1 interacts with the carbohydrate components of the Gram-negative bacterial cell wall. Retention of chitinase and bacterial agglutination activities in transplastomic tobacco extracts implicates that BjCHI1 is potentially useful against both fungal and bacterial phytopathogens in agriculture.
Chitinase-Mediated Inhibitory Activity of Brassica Transgenic on Growth of Alternaria brassicae
Current Microbiology, 2003
Chitinase, capable of degrading the cell walls of invading phytopathogenic fungi, plays an important role in plant defense response, particularly when this enzyme is overexpressed through genetic engineering. In the present study, Brassica plant (Brassica juncea L.) was transformed with chitinase gene tagged with an overexpressing promoter 35 S CaMV. The putative transgenics were assayed for their inhibitory activity against Alternaria brassicae, the inducer of Alternaria leaf spot of Brassica both in vitro and under polyhouse conditions. In in vitro fungal growth inhibition assays, chitinase inhibited the fungal colony size by 12-56% over the non-trangenic control. The bioassay under artificial epiphytotic conditions revealed the delay in the onset of disease as well as reduced lesion number and size in 35S-chitinase Brassica as compared to the untransformed control plants.
Overexpression of NPR1 in Brassica juncea Confers Broad Spectrum Resistance to Fungal Pathogens
Frontiers in plant science, 2017
Brassica juncea (Indian mustard) is a commercially important oil seed crop, which is highly affected by many biotic stresses. Among them, Alternaria leaf blight and powdery mildew are the most devastating diseases leading to huge yield losses in B. juncea around the world. In this regard, genetic engineering is a promising tool that may possibly allow us to enhance the B. juncea disease resistance against these pathogens. NPR1 (non-expressor of pathogen-related gene 1) is a bonafide receptor of salicylic acid (SA) which modulates multiple immune responses in plants especially activation of induced and systemic acquired resistance (SAR). Here, we report the isolation and characterization of new NPR1 homolog (BjNPR1) from B. juncea. The phylogenetic tree constructed based on the deduced sequence of BjNPR1 with homologs from other species revealed that BjNPR1 grouped together with other known NPR1 proteins of Cruciferae family, and was nearest to B. napus. Furthermore, expression analy...