Root and basal rot of common onion (Allium cepae L.) caused by Fusarium oxysporum f. sp. cepae is one of the most important diseases causing tremendous losses in onion‐growing areas worldwide. In ...this study, random amplified polymorphic DNA (RAPD), intersimple sequence repeats (ISSR) and virulence studies were conducted to analyse 26 F. oxysporum f. sp. cepae isolates obtained from the main onion‐growing regions of Iran, including Fars, Azerbaijan and Isfahan states. Cluster analysis using UPGMA method for both RAPD and ISSR markers revealed no clear grouping of the isolates obtained from different geographical regions, and the isolates were observed to derive probably from the same clonal lineage. Pathogenicity test indicated that all F. oxysporum f. sp. cepae isolates were pathogenic on onion; however, virulence variability was observed among the isolates. The grouping based on virulence variability was not correlated with the results of RAPD and ISSR analyses.
Early blight disease of tomato is one of the most devastating biotic stresses worldwide, and in Iran, Alternaria alternata is one of the most predominant species causing the disease. In the current ...study, a diverse collection of 35 tomato genotypes and implication of 5 SlWRKYs and 7 PR genes as well as enzymatic activity were evaluated on resistant and susceptible cultivars through real-time polymerase chain reaction at transplanting and maturing stages and by measuring product formation using spectrophotometry. The results indicated that the expression of these antifungal genes in 14 genotypes at two growth stages after inoculation with A. alternata highly enhanced by 1–50-fold. There was also significant upregulation of WRKYs and PRs genes among the resistant tomato varieties in comparison to susceptible and control varieties at both stages. These findings demonstrate the varieties that showed increased or decreased SlWRKY1 expression also displayed similar changes in the expression of PR1 and PR2 genes. Furthermore, the differential expression patterns of SlWRKY1 and SlWRKY11 were consistent with PR7 and PDF1.2 expression patterns. The analysis of enzymatic activity of PR2 and PR3 proteins, β-1,3-glucanase, and chitinase showed the highest level of activity in resistant inoculated genotypes against A. alternata. Therefore, the current findings suggest the possible involvement of these transcription factors in the increased expression of PR genes in response to A. alternata infection.
•Some tomato varieties are resistant to early blight disease caused by A. alternata.•The expression of defense-related genes provides EB disease resistance.•Chitinase and glucanase contribute to resistance to EB disease in tomato.•Expression and enzymatic activity of chitinase and glucanase are directly related.
Early blight disease (EB), Alternaria alternata, is destructive on Solanum lycopersicum Mill. The responses of 35 domestic and exotic commercial tomato genotypes to early blight were examined at ...transplanting and maturing stages using genetic diversity analysis, with 15 Inter Simple Sequence Repeat (ISSR) primers, total phenolic content (TPC), and enzymatic activity of catalase (CAT), phenylalanine ammonia lyase (PAL), peroxidase (POD) and superoxide dismutase (SOD) assays. The disease severity ranged from 18 to 87.5%. Eleven of 15 ISSR primers generated 68 loci of which 63 (90%) were polymorphic. Polymorphism information content value varied from 0.3 to 0.5 with an average of 0.4. Nei's measure of the average gene diversity ranged from 0.06 to 0.5. The Tomato genotypes were divided into five clusters in Un-weighted Pair Group Method with Arithmetic Mean (UPGMA) analysis, showing a considerable similarity between resistance level and molecular classification pattern. Antioxidant analysis indicated a significant increase in TPC and CAT, POD, PAL and SOD activities in most inoculated tomato genotypes at both growth stages. The highest increase in activity was seen in PAL (5-fold) and TPC (4-fold) at transplanting stage, whereas the highest TPC (2 to 3-fold) and POD activity (3-fold) were found at maturing stage in all the inoculated resistant genotypes in comparison with controls. Esfahan Local and H. a.s 2274 showed the highest level of activity in POD (2.5- and 3- fold, respectively) and TPC (2.5- and 4-fold, respectively). Our results suggest that using both genetic diversity and enzymatic diversity as markers, it is possible to discriminate resistant from susceptible tomato genotypes to early blight disease.
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•Tomatoes exhibit differential resistance to early blight disease (EB) A. alternata.•ISSR markers appear useful for clustering tomatoes based on EB resistance level.•The enzymatic antioxidant activities provide EB disease resistance.•Total phenol content contributes to resistance to EB disease in tomato.
Iris is one of the most popular and best-selling ornamental plants around the globe. Fusarium root rot disease, Fusarium oxysporum f.sp. gladioli (FOG) is one of the most serious disease of Iridaceae ...and Iris plants. In this study, three resistant and three susceptible Iris genotypes were inoculated with FOG isolates to evaluate expression of related genes promoting defense to disease at intervals times at two, four and six weeks post inoculation. Total RNA was extracted using an AccuZol™ reagent, and the first-strand Cdna was synthesized accordingly. Expression level of WRKY transcription factors (WRKY), lectin receptor kinase (LecRK), pathogenesis-related protein (PR3), lipoxygenase (LOX1) and ribosome-inactivating proteins (RIP) genes was investigated using quantitative polymerase chain reaction (qPCR). The transcriptional level of five defense-related genes were up-regulated in FOG-infected samples. The genes expression in resistant Iris genotypes NIOP3, NIOP15 and NIOP16 was much higher than susceptible NIOP1, NIOP12 and NIOP20 genotypes. The highest level of expression was observed in all the genes and genotypes at 6 weeks post inoculation. The phenotypic symptoms of genotypes and changes in the expression of genes confirmed resistance in Iris genotypes NIOP3, NIOP15 and NIOP16 in comparison to susceptible genotypes NIOP1, NIOP12 and NIOP20, and un-inoculated control Iris plants. Identifying disease-resistant genotypes can contribute to the development of new ornamental cultivars that can be deployed to ensure high quality and lasting Iris plants.
•Molecular analysis of five involving defense genes; WRKY, LecRK, PR3, LOX and RIP were performed for the very first time in Iris plants.•Pathogenicity of Iris plants with F. oxysporum f.sp. gladioli increases the expression of defense-related genes.•This contributes developing of new ornamental cultivars that can be deployed to ensure high quality and lasting Iris plants.•It provides strategies to determine the role of genes associated with defense in plant and help identify resistant varieties.
Phytophthora melonis
is one of the most destructive cucumber disease, causing severe economic losses in the globe. Despite intense research efforts made in the past years, no permanent cure currently ...exists for this disease. With the aim to understand the molecular mechanisms of defense against
P. melonis
, root collars and leaves of four cucumber genotypes consisting of resistant Ramezz; moderately resistant Baby, and very susceptible Mini 6-23 and Extrem, were monitored for quantitative gene expression analysis of the five antifungal and/or anti-oomycete genes (
CsWRKY20
,
CsLecRK6.1
,
PR3
,
PR1-1a
and
LOX1
), at three points after inoculation with
P. melonis
. The gene expression analysis indicated,
P. melonis
strongly enhanced the expression of these genes after inoculation, in both the leaves and root collars. Further, not only the transcript levels of these genes were significantly higher in resistant and moderately resistance genotypes, but also the time point of the highest relative expression ratio for the five genes was different in the four cucumber genotypes.
CsWRKY20
and
PR3
showed the maximum expression in Ramezz at 48 h post inoculation (hpi) while
CsLecRK6.1
, and
LOX1
showed the highest expression at 72 hpi. In addition,
PR1-1a
showed the maximum expression in the Baby at 72 hpi. Root collars responded faster than leaves, and some responses were more strongly up-regulated in root collars than in leaves. The genes found to be involved in disease resistance in two different organs of cucumber after pathogen infection. The results suggest that increased expression of these genes led to activation of defense pathways, and could be responsible for a reduced
P. melonis
colonization capacity in Ramezz and Baby. Overall, this work represents a valuable resource for future functional genomics studies to unravel molecular mechanisms of
Cucumis sativus
–
P. melonis
interaction.
Rhizoctonia solani Kühn AG3-PT causes stem canker (SCD), and significantly impacts potato, Solanum tuberosum L. production globally. However, up to date, there are few resistant or tolerant potato ...cultivars to R. solani. Given the importance of the subject, we screened ninety-two potato genotypes to SCD, R. solani in the field and greenhouse conditions. Of which, fifty genotypes were subjected to genetic diversity analyzing using 20 Inter Simple Sequence Repeats (ISSR) primers. SCD severity on genotypes ranged from 5 to 73% in the field, and out of 20 used ISSR primer pairs, 14 primers generated 485 loci, of which 216 (45%) showed polymorphic bands. The highest percentage (67%) of polymorphisms was in uBC834 primer. Polymorphism information content value varied from 0.262 to 0.459 with an average of 0.338. Nei's measure of average population genetic diversity per locus ranged from 0.06 to 0.5. Effective number of alleles, Nei's genetic diversity and Shannon's Information Index were 1.530, 0.266, and 0.392, respectively. uBC834 and uBC811 primers identified the most polymorphic loci. According to simple-matching coefficient, the highest similarity (99%) was among “KSG64”, “KSG82”, “KSG81”, “KSG21”, “KSG31”, and “KSG109”, and lowest similarity (54%) in “8708/177” and “KSG300”. Thus, resistant sources can play a significant role in disease management in an integrated pest management planning program. Moreover, diverse potato resistant/susceptible genotypes reported in this study will be useful to generate mapping populations for potato and work in breeding programs for developing and releasing new resistant cultivars for SCD, R. solani infection.
•Potato cultivars had different responses to the stem canker disease fungus, R. solani.•Resistant genotypes can be used in the transfer of resistant genes in cultivated and economic potato cultivars.•Stem canker disease caused significant reduction in biomass factors in infected genotypes.•ISSR markers are suitable for potato genetic diversity analysis.•ISSR markers and their implementation are easy and cost-effective.
Fusarium wilt of melon, Cucumis melo L. (Cucurbitaceae) caused by Fusarium oxysporum f. sp. melonis (FOM), induces severe symptoms, thus dramatically limiting the yield in melons globally. ...Incorporating genetic resistance in cultivated crops is considered the most efficient and sustainable solution to control root rot diseases. However, resistance to FOM in melon is quantitative in nature, and the mechanism is poorly understood, and the information about melon-FOM race interactions is still limited. This study explored the changes in the eight antioxidant enzyme activities; catalase (CAT), chitinase (CHI), β-1,3-glucanase (GLU), peroxidase (POX), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), superoxide dismutase (SOD), and as well as total phenol contents (TPCs) in roots of two resistant ‘Shante-F1’ and ‘Khatooni’ and two susceptible ‘Shante-T’ and ‘Shahabadi’ melon accessions, over the time courses of 7, 14 and 21 days (dpi) following inoculation with an isolate of FOM race-1.2.The results revealed that the up-regulated of this set of defense-related enzymes was a key factor against FOM race-1.2 infection, with levels being elevated up to 3-fold in the resistant accessions. In addition, biomass growth parameters (BMPs), roots and shoots (fresh and dry weights, heights, diameters and roots volume) following inoculation displayed almost similar trends observed for the enzyme activity in resistant melon accessions in comparison to susceptible ones. Thus, studying the physiological metabolic pathways of the related enzymes appears to be an important biochemical marker for breeding programs aiming to elucidate the FOM race 1.2 resistance mechanisms in melon. A better insight in melon defense responses can help to establish biochemical characteristics for the selection of resistant melon sources and provide a theoretical basis for disease control and breeding of melon plants with higher levels of resistance to FOM race 1.2 isolates.
A- View of the related melons at glasshouse. B- Resistant Chante-F1. C- Resistant Khatooni. D- Susceptible Chante-T, and E− Susceptible ‘Shahabadi’. D and E also show typical symptoms of Fusarium wilt in melon seedlings; D- Symptoms of wilting, and E- Symptoms of yellowing. Display omitted
•There are certain resistant melons to Fusarium Wilt-Fusarium oxysporum f. sp. melonis race-1.2 pathosystem.•Activity of certain enzymes contribute to Fusarium Wilt-race-1.2 resistance in melons.•Up-regulation of enzymes; SOD, PPO and POX were significantly higher in resistant melons.•There is a significant correlation either between resistance, enzyme activity, and or biomass parameters variability.•Introduced melons should be explored as a potential source of donor resistance genes in breeding programs.
Early blight (EB), caused by the dominant species
Alternaria alternata
, is a major global disease of tomato (
Solanum lycopersicum
L.; Solanaceae) reducing the vegetative organs and causing losses. ...Sustainable food production mainly depends on the rational use of chemical fertilizers and fungicides in integrated plant disease management. Hence, the fungicidal activity of ortivatop
®
(azoxystrobin + difenoconazole), Signum WG 33.4% (pyraclostrobin + boscalid) and daconyl SC 72% (chlorothalonyl) was evaluated against tomato EB disease under field conditions. Two experiments were conducted during the cropping seasons from 2019 to 2020 in three regions. The experimental design was a randomized block with 4 replications using Ortivatop
®
(ORT) at three doses of -900, -1100 and -1300 ml. ha
−1
(recommended doses of the company), daconyl (DAC) 2 l. ha
−1
and Signum (SIG) 0.5 l. ha
−1
. The findings showed that ORT-1300 (20.6%) and DAC (22.7%) resulted in the lowest EB disease severity, followed by SIG (25.7%), ORT-1100 (26.9%) and ORT-900 (31.7), in contrast to 59.1% of the control. Compared with treatment without fungicide, all fungicides reduced the AUDPC (area under disease progress curve) and provided an increase in productivity. ORT-1300 ml ha
−1
showed the greatest reduction in AUDPC by up to 70% and increased tomato yield by threefold more than the untreated control. Therefore, the current study suggests that foliar spraying with ORT-1300 ml. ha
−1
at all three growth stages, is an ideal solution for EB disease management.
Cucumber (Cucumis sativus L.) damping-off disease caused by Phytophthora melonis is a limiting factor affecting cucurbit production. This study assessed a collection of 38 domestic and exotic ...commercial cucumber genotypes for damping-off resistance at transplanting and 50% flowering. Plants were classified using a four-score scale, the average damping-off percentage ranging from 7.92% (resistant) to 88.01% highly susceptible (HS). Most of the genotypes were susceptible and HS to P. melonis. These genotypes were analyzed with 15 inter-simple sequence repeat (ISSR) markers. A total of 317 bands were produced, of which 297 bands (93.69%) were polymorphic. The primer ISSR29 possessed the highest resolving power, polymorphic information content and marker index value, which could be the most informative primer for distinguishing cucumber genotypes. Cluster analysis and principal component analysis were carried out and there was a probable connection between cucumber genotypes and resistance level against P. melonis, indicating possible application for ISSR in studying disease resistance of cucumber and producing cultivars that resist damping-off. The expression of three candidate genes probably involved in the defence against P. melonis was quantified by quantitative real-time polymerase chain reaction in five cucumber genotypes showing different susceptibility to the pathogen. CsWRKY20, CsLecRK6.1 and LOX1 genes were differentially expressed depending on genotype in early stages of infection. LOX1 was the most expressed gene across experiments and the one that best discriminated between susceptible and resistant genotypes. These results are a valuable resource for future functional genomics studies to unravel the molecular mechanisms of C. sativus/P. melonis interaction.
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