جستجوی مقالات مرتبط با کلیدواژه "defense response" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

Neonectria ditissima, the causal agent of fruit tree canker, is one of most destructive diseases of apple trees in producing countries with cool weather. Since it is difficult to control this disease due to the presence of the pathogenic fungus throughout the year, for better understanding of this host–pathogen interaction in order to improve management strategies, a transcriptional analysis of apple gene expression in response to N. ditissima was conducted.

In the present study, we evaluated transcriptome responses to N. ditissima by selecting the partially resistant cultivar “Jonathan”. The leaf scars of apple trees were artificially inoculated with suspension of N. ditissima and water as control. Then the samples were taken for RNA extraction at three different time points, 5, 15, and 30 days after inoculation. The quality and quantity of the extracted RNA were checked and total RNA was sequenced using Illumina paired-end sequencing and Hiseq2000 sequencer. The quality of the sequence data was done by FastQC software. Then the reads were mapped to apple reference genome by TopHat2 software. Normalization and differential expression analysis of genes were performed with DESeq2. Enrichment analysis of DEGs pathways was done through KEGG software.

Based on GO enrichment and KEGG pathway analyses, it was found that some of the defense response genes were differentially expressed between control and treatment groups. The data provides evidence that apple cultivars inoculated with N. ditissima exhibit significant upregulation of defense-related genes and genes involved in detoxification, peroxidase related reactions, phenylpropanoid metabolism. The highest expression level of genes related to defense was observed 30 days after inoculation. It shows that the pathogen needs time to cause infection and cannot spread quickly in the plant tissue.

Identification of candidate genes involved in pathogenicity of N. ditissima are involved in lignification, detoxification, phosphorylation and pathogen defense. They are a valuable resource in genetic research and allow us to better understand interaction of fungus and the apple defense system, and may assists in apple canker breeding programs.

Beet curly top Iran virus (BCTIV) is a destructive virus causing damage to agriculture industry annually. BCTIV has a circular single-stranded DNA genome with five open reading frames (ORFs): V1, V2 and V3 on genomic strand, and C1 and C2 on complementary strand. V2 acts as a suppressor of silencing interfering with this defense pathway. This study was aimed to determine the evolutionary characteristics and genetic structure of V2 among different BCTIV isolates.

Total number of 31 BCTIV V2 nucleotide sequences were extracted from the GenBank and analyzed. The nucleotide sequence was aligned and the phylogenetic tree was drawn. Nucleotide polymorphism analysis was determined. Also, the occurrence of insertion-deletion polymorphism (InDel) was investigated. Nonsynonymous (dN) and synonymous (dS) substitution rates and dN/dS ratio were calculated in order to check the selection pressure on nucleotide sequences and V2 codons. Entropy analysis was also performed to investigate possible variations in nucleotide positions.

Based on the host and geographical location, V2 sequences were placed in different clusters of the phylogenetic tree. 20 haplotypes and 94 polymorphic loci was detected. Haplotype and nucleotide diversity was calculated as 0.963 and 0.06517, respectively. The mean nucleotide differences was 23.463. InDel polymorphism was not observed. The rates of dN and dS were calculated as -0.60699 and 0.03020, respectively, both of which were not significant. The dN/dS ratio was also -20.10201. Total number of 26 positions among the codons showed a positive value of dN/dS ratio, while 34 positions had a negative value. Also, at least 9 recombination events were observed. Entropy analysis showed that nucleotide position 247 has the most changes with an entropy rate of 0.93.

The results suggest that the variation in the nucleotide sequence of BCTIV V2 can be effective in suppressing gene silencing and the pathogenicity of different isolates in different hosts. The variability of this part of the virus genome may in the future lead to an increase in the range of host range of the virus or to overcome the resistance of plant varieties.