Key Message Novel major gene resistance against Potato virus Y in diploid populations of Solanum tuberosum Groups Phureja and Tuberosum was biologically and genetically characterised. Named Ry(o)phu, it mapped to chromosome 9. Abstract A new source of genetic resistance derived from Solanum tuberosum Group Phureja against Potato virus Y (PVY) was identified and genetically characterised in three diploid biparental potato populations. Segregation data for two populations (05H1 and 08H1) suggested the presence of a single dominant gene for resistance to PVY which, following DaRT analysis of the 08H1 cross, was mapped to chromosome 9. More detailed genetic analysis of resistance utilised a well-characterised SNP-linkage map for the 06H1 population, together with newly generated marker data. In these plants, which have both S. tuberosum Group Phureja and S. tuberosum Group Tuberosum in their pedigree, the resistance was shown to map to chromosome 9 at a locus not previously associated with PVY resistance, although there is evidence for at least one other genetic factor controlling PVY infection. The resistance factor location on chromosome 9 (named as Ry(o)phu) suggests a potential role of NB-LRR genes in this resistance. Phenotypic analysis using a GUS-tagged virus revealed that a small amount of PVY replication occurred in occasional groups of epidermal cells in inoculated leaves of resistant plants, without inducing any visible hypersensitive response. However, the virus did not enter the vascular system and systemic spread was completely prevented.

This study was conducted to isolate and molecularly identify two pathogenic fungi namely Rhizoctonia solani and Fusarium solani implicated in root rot and seedling damping-off disease of cucumber, Cucumis sativus. Besides, the efficacy of Pseudomonas fluorescens and Bacillus subtilis as bacterial agents in controlling these two pathogens was also evaluated in vitro and in a greenhouse pot experiment. Results of polymerase chain reaction (PCR) amplification and nucleotide sequence analysis using BLAST demonstrated that R. solani isolate was genetically different from the R. solani isolates in the National Centre for Biotechnology Information (NCBI). Therefore, it was recorded in GenBank under the accession number MK105921. P. fluorescens and B. subtilis showed a complete inhibition of the mycelial growths of R. solani and F. solani in vitro. In the pot experiments, soil treatment with a suspension of P. fluorescens and B. subtilis before planting significantly reduced the damping off of cucumber seedlings caused by R. solani and F. solani. This study suggests that these bacterial antagonists could have a good potential as biological control agents to protect cucumber plants from the infection with R. solani and F. solani.

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The study was carried out, in the laboratory of Plant Virology, Plant Protection Department, College of Agriculture, University of Kerbala, to isolate and identify six isolates of the fungus Cladosporium sphaerospermum isolated from different environments (seeds, air, plant residues, and soil) in Al-Najaf province, Iraq. The fungal isolates were identified using the polymerase chain reaction (PCR) and determining the nucleotide sequence products of DNA using ITS1 and ITS4 primer pair. Results of analysis of the nucleotide sequences using BLAST (Basic Local Alignment Search Tool) showed that all the identified isolates of the fungus belong to C. sphaerospermum. A comparison of the nucleotide sequences with those available in the National Centre for Biotechnology Information (NCBI) revealed that all the identified C. sphaerospermum sequences were previously registered in NCBI.

This study was conducted at the Agriculture College University of Karbala, Iraq to isolate and morphologically and molecularly diagnose thirteen Cladosporium isolates collected from tomato plant residues present in desert regions of Najaf and Karbala provinces, Iraq. We diagnosed the obtained isolates by PCR amplification using the ITS1 and ITS4 universal primer pair followed by sequencing. PCR amplification and analysis of nucleotide sequences using the BLAST program showed that all isolated fungi belong to Cladosporium sphaerospermum. Analysis of the nucleotide sequences of the identified C. sphaerospermum isolates 2, 6, 9, and 10 showed a genetic similarity reached 99%, 98%, 99%, and 99%, respectively, with those previously registered at the National Center for Biotechnology Information (NCBl). By comparing the nucleotide sequences of the identified C. sphaerospermum isolates with the sequences belong to the same fungi and available at NCBI, it was revealed that the identified C. sphaerospermum isolates 2, 6, 9, and 10 have a genetic variation with those previously recorded at the National Center for Biotechnology Information (NCBl); therefore, the identified sequences of C. sphaerospermum isolates have been registered in GenBank database (NCBI) under the accession numbers MN896004, MN896107, MN896963, and MN896971, respectively.

This study was conducted to isolate and identify Trichoderma harzianum Rifai and Rhizoctonia solani by the polymerase chain reaction (PCR) technique with the presence of the ITS1 and ITS4 primer pair. The study was also carried out to investigate the efficacy of rice husk compost fortified with the bio-control agent, T. harzianum for the resistance of wheat seeds to the pathogenic fungus, R. solani, and to evaluate the effect of the compost on wheat germination and seedling, and irrigation water usage. The results showed that the highest germination rate which was found to be 100% was achieved with the T.h.+S treatment while the lowest germination was 93.3% with both the T.h.+RHC+S and R.s.+RHC+S treatments compared to germination of 96.6% with the control treatment. The RHC+S treatment resulted in the highest percentage of rotting seeds which was 10% while the lowest percentage of rotting seeds which reached 0% was achieved with the T.h.+S treatment. The results also showed that with R.s.+RHC+S and T.h.+RHC+S treatments, the highest shoot length at 21 post-planting days was achieved which was found to be 1.3 cm and 1.2 cm, respectively compared to other treatments including the control. Regarding fresh and dry weights, treatments with RHC had significantly much higher fresh and dry weights than all other treatments. It was clear from the experimental results that the highest number of branches/plant was recorded in the treatment of T.h.+RHC+S that was 5.3 followed by RHC+S treatment with 4.6 while the lowest number of branches/plant was recorded in the control treatment which was only 1.8. Amount of water used for irrigation in treatments of T.h.+RHC+S and R.s.+RHC+S was reduced to be 233.33 compared to 600.00 in the control treatments. The highest chlorophyll content was 2.4 and was recorded in the treatment of R.s.+RHC+S with a significant difference from all other treatments. The T.h.+S treatment gave the lowest chlorophyll content. In fact, treatments that incorporated RHC had always higher values of plant total chlorophyll contents. Earliest flowering was achieved with the RHC+S treatment while the R.s.+S treatment resulted in the latest flowering.

Soybean sudden death syndrome (SDS) caused by Fusarium virguliforme is a common and widespread disease across soybean-growing regions worldwide. Experiments were conducted in temperature-controlled water baths in the greenhouse to test the effects of some genes from syntaxin group (SYP22-3 and SYP22-4) on F.virguliforme and the combination of SDS and soybean cyst nematode (Heterodera glycines). Both genes were tested in different combinations with currently two pathogens to examine their ability to manage studied pathogens. Syntaxin evaluated on soybean seedlings infected with F. virguliforme alone and both F. virguliforme and H. glycines. Results showed that there were significant effects of syntaxin genes to reduce the foliar disease severity on soybean plants. Furthermore, they reduced the number of H. glycines females cysts compared to control. Data analysis did not show any negative effect by syntaxin genes on plant growth.

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