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Showing 3 results for Chitin

Mitra Khademi, Farhad Nazarian-Firouzabadi,
Volume 6, Issue 1 (9-2019)
Abstract

Recently, new molecular breeding and genetic engineering approaches have emerged to overcome the limitations of conventional breeding methods in generating disease-resistance transgenic plants. The use of antimicrobial peptides (AMPs) to produce transgenic plants resistant to a wide range of plant pathogens has achieved great success. Among huge number of AMPs, Dermaseptin B1 (DrsB1), an antimicrobial cationic 31 amino acids peptide, exhibits significant antimicrobial activities towards a wide range of pathogens. In order to increase the antimicrobial efficacy of DrsB1, the DrsB1 encoding DNA sequence was either fused to the N- or C-terminus of the sequence encoding chitin-binding domain (CBD) of Avr4 gene from Cladosporium fulvum and constructs (CBD-DrsB1 and DrsB1-CBD) were used for tobacco leaf disk Agrobacterium-mediated transformation. Polymerase chain reaction (PCR), semi-quantitative RT-PCR and SDS-PAGE analysis indicated the integration of transgenes in tobacco genome and expression of the recombinant genes in transgenic plants, respectively. The antimicrobial activity of extracted recombinant peptides were assessed against a number of plant and human pathogens. Both recombinant peptides had statistically significant (P<0.01) inhibitory effects on the growth and development of fungi pathogens. Also, CFU test result showed that extracted recombinant peptides from transgenic plants, had a relatively high inhibitory effect on plant pathogens. The CBD-DrsB1 recombinant peptide demonstrated a higher antibacterial activity, whereas the DrsB1-CBD recombinant peptide performed a greater antifungal activity. In addition, the expression of DrsB1-CBD recombinant peptide significantly inhibited R.solani fungal infection in comparison with Pythium sp. interestingly, fungi with a higher amount of cell wall chitin were more vulnerable to recombinant peptides, suggesting recombinant peptides present a higher affinity for cell wall chitin. Owing to the high antimicrobial activity and novelty of recombinant peptides, this strategy for the first time, could be used to generate transgenic crop plants resistant to devastating plant pathogens.

Seyedeh Sanaz Ramezanpour, Hassan Soltanloo, Saied Navabpour,
Volume 10, Issue 2 (2-2024)
Abstract

To evaluate the effect of fungus Blumeria graminis (powdery mildew disease) on expression of genes associated with resistance reactions in barley, a susceptible cultivar (Afzal), a semi-susceptible genotype (Line 67) and a resistant genotype (Line 104) were selected. Following inoculation with Blumeria graminis at seedling stage, sampling was performed at different time points (0-10 days). Changes in gene expression levels were measured by qRT-PCR analysis. Analysis of molecular data showed that the genes encoding chitinase and glucanase as the key enzymes in fungal cell wall degradation, had higher expression levels in the resistant genotype (Line 104). The transcript level of chitinase in semi-susceptible genotype (Line 67) was lower than that of the resistant genotype (Line 104) and higher than that of the susceptible cultivar. Most transcripts of chitinase gene were seen at 12 hours post inoculation in the resistant genotype (Line 104), whereas the lowest expression level was recorded at the same time in the susceptible cultivar. The expression levels of the other two genes (glucanase and peroxidase) were higher in the resistant genotype (Line 104) than those in the susceptible cultivar. Increasing in MAPK transcripts in resistant genotype (Line 104) and its depletion in susceptible cultivar confirmed MAPK role in Hypersensitive response (HR) and defense responses of barley infected with powdery mildew disease. Based on the findings of this study, it appears that the HR in the resistant genotype initiated as early as six hours post inoculation, effectively hindering the penetration and dissemination of the pathogen within the plant. Such reaction was not observed in the semi-susceptible and susceptible barley plants, possibly due to delayed in responses, allowing the pathogen ample time to penetrate and propagate within the host plant. The results of this research can be used to evaluate the resistance level of cultivars and also to evaluate the resistance in the seedling stage of promising lines.

Fatemeh Hatami, Farhad Nazarian-Firouzabadi, Seyed Sajad Sohrabi, Mitra Khademi,
Volume 11, Issue 1 (9-2024)
Abstract

Saffron (Crocus sativus L.) is not only one of the most expensive food products in Iran and the world but also holds a special place among Iran's export and industrial products. Since saffron is propagated only through corms, preventing the contamination of corms as “seed” with devastating pathogens is crucial to maintaining the quality and yield of the saffron. Hence, investigating the genetic mechanisms associated with the response of the saffron plant to fungal pathogens such as fusarium wilt rot (Fusarium oxysporum) is of great importance. Given that plants express a wide range of resistance genes to defend themselves, the role of genes related to the PTI (Pattern-Triggered Immunity) pathway, such as those in the LysM-RLK family, is crucial in pathogen resistance. Therefore, studying the transcriptome of saffron corms infected with the pathogen Fusarium oxysporum is important for identifying and investigating the genes belonging to the RLP and RLK gene families. Plants express a wide range of resistance genes to respond to pathogens attacks. Among different gene families associated with PTI pathway, the LysM-RLK family plays an important role in resistance to pathogens. Therefore, in this study, the transcriptome of saffron corms infected with the Fusarium oxysporum was studied to identify and investigate the genes belonging to the RLP and RLK gene families. According to the results of this study, a total of 45 genes encoding PTI pathway receptors were identified in the saffron transcriptome, with 40 sequences belonging to the RLP (Receptor-like proteins) family and 5 sequences to the RLK (Receptor-like kinases) family. The expression analysis of some main RLP and RLK family members showed that the highest expression was related to the sequences of Contig 41583 (RLP) and Contig 61879 (RLK) in the saffron stigma and corms, respectively. Furthermore, the expression of the selected genes in the infected corms significantly increased compared to the control healthy corm. Additionally, the expression levels of the target genes (Contig 41583 and Contig 61879) assessed using qRT-PCR indicated higher expression in corms 72 hours post-infection compared to 48 hours post-inoculation. These results suggest that RLK proteins play a crucial role in the interaction between saffron and the pathogen, particularly due to the presence of the LysM motif. Since LysM motif binds to chitin oligomers of fungal cell walls of certain fungi and oomycetes, it triggers plant immune responses. Overall, the findings of this study are significant for understanding the specific nature of the plant-pathogen relationship and can contribute to insights into the PTI immune pathway.


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