Plant Pathology Science

Screening of fifteen tomato varieties for resistance to early blight disease

Mehdi Sadravi

Bavand, M., Sadravi, M., & Charehgani, H. (2023). Screening of fifteen tomato varieties for resistance to early blight disease. Plant Pathology Science 12(2),1-10.
Introduction: Early blight caused by Alternaria species is one of the major tomato diseases worldwide, causing losses of up to 86% of yield. Identifying and cultivating resistant varieties is the best method for disease management. Considering the prevalence and importance of diseases in Iran, this study was conducted to identify resistant cultivars among 15 available varieties. Materials and Methods: In Kohgiluyeh and Boyer-Ahmad province in southwestern Iran, a severely affected tomato field by the disease was visited and samples of the diseased plants were taken. The pathogenic fungus was isolated on potato dextrose agar medium from the diseased tissues of the plant after their surface disinfection and after its purification by the single spore method and its morphological properties were examined and measured. The collected data were compared with the descriptions of Alternaria species and based on that, the pathogen was identified. Seedlings of 15 tomato varieties were inoculated with a conidia suspension at the 4-leaf stage in a completely randomized statistical design and maintained in a growth chamber with a temperature of 28^oC, relative humidity of 90%, and a photoperiod of 16 hours of light and eight hours of darkness. Eighteen days after inoculation, the response of each cultivar to the disease was determined by calculating the percentage of infected leaves as well as the number and size of spots, and the disease index. Results: Alternaria alternata has been identified as the cause of early blight in tomatoes in this region. Varieties 10552, King Stone, Super Chief and Ventero with minimal symptoms were scored as resistant; 4129, 3725, 4224, Retino, Aras, Flat 111 and Super Pooya as semi-resistant and 7806, Early Pooya, 11057 and CH Pooya were known to be susceptible to the disease. Conclusion: Cultivation of resistant or semi-resistant varieties can be recommended for disease control. The occurrence of tomato blight disease caused by A. alternata is reporting here for the first time from the region.

The reaction of four pumpkin varieties to cucumber mosaic virus by analyzing the expression of PAL and PR2 genes

Sevil Nematollahi

Jahandideh M, Nematollahi S, Rakhshandehroo F (2023) The reaction of four pumpkin varieties to cucumber mosaic virus by analyzing the expression of PAL and PR2 genes. Plant Pathology Science 12(2):11- 26.

Introduction: Cucumber mosaic virus (CMV) is one of the most important pathogenic cucurbit viruses. Identifying and growing resistant or tolerant varieties is the best method for disease control. The present study was conducted to investigate the response of four pumpkin varieties to CMV by assessing the expression of genes involved in resistance (PAL, PR2). Materials and Methods: Forty samples of pumpkin leaves with suspected disease were collected from the farms in northwestern Iran and analyzed using the TAS-ELISA test. To study the response of the four pumpkin varieties Asma, Pars, Prof and PS grown in this region, a CMV isolate was inoculated into the plants in a greenhouse experiment after its biological purification. TAS-ELISA and semi-quantitative (Sq) RT-PCR tests were used to examine the virus concentration in pumpkin varieties. The disease severity index was evaluated 30 days after inoculation. The expression level of PAL and PR2 genes was also checked by quantitative real-time PCR technique. Results: Of the 40 samples, 16 samples were infected with CMV. The study of virus titer revealed that the virus concentration and disease severity index were higher in Pars and Proof varieties than in PS and Asma varieties. The expression of PAL and PR2 genes was increased in all varieties compared to control but was higher in PS cultivar followed by Asma. Conclusion: PS and Asma varieties have higher CMV tolerance and their wider cultivation is recommended for disease control.

The effect of four herbal compounds on root-knot nematode of kiwi

Salar Jamali

Kazemian F, Jamali S, Alipour Z, Nasaj Hosseini SM (2023) The effect of four herbal compounds on root-knot nematode of kiwi. Plant Pathology Science 12(2):27-40.

Introduction: Root-knot nematodes damage is one of the major problems in kiwifruit production in northern Iran. This research was carried out to investigate the possibility of using dried leaves of four plants to manage kiwifruit root-knot nematode. Materials and Methods: The soil and roots of diseased kiwifruit from the gardens of Rudsar City, Gilan Province, Iran were sampled and their root knot nematode was purified using the single egg mass method on the early Urbana tomato variety. The morphological characteristics of nematode second stage larvae and females were examined and nematode species were identified. By using the single egg mass technique, the necessary nematode population was reared on the early Urbana tomato. The effect of dry leaves of chrysanthemum, parsley, guava and oleander in two rates of 50 and 75 grams per kilogram of soil was evaluated in greenhouse conditions. The experiment was conducted in a completely randomized design with four replicates for each treatment on nematode-inoculated kiwi seedlings of Hayward cultivar. Nematode-related indices (number of galls, egg mass, eggs and J2s in 250 g of soil and reproductive factor) and plant growth characteristics (seedling height; root length and volume; fresh and dry weight of roots and shoots) were measured. Results: The root- knot nematode causing the disease in this region was identified as Meloidogyne incognita. In addition to controlling the nematode, the treatments used improved the growth of the kiwi seedlings. The results of the mean comparison of data showed that the treatment of 75 g of chrysanthemum leaves had a greater effect on reducing nematode population indices than other treatments. The next effective treatments were chrysanthemum at the rate of 50g, parsley at the rate of 75g, parsley at the rate of 50g, oleander at the rate of 75g, oleander at the rate of 50g, guava at the rate of 75g and guava at the rate of 50g, respectively. Treatment with 75 g of chrysanthemums also had the greatest effect on improving the growth rate of tomato seedlings. Conclusion: Adding 75g of dry chrysanthemum leaves to each kilogram of soil will help reduce root nematode damage and improve the growth of kiwi seedlings.

Report of six plant parasitic nematodes from the orchards of Rafsanjan region, Kerman Province, Iran

Mahdieh Rostami

Sharify Rostam-Abadi S, Rostami M, Jahanshahi Afshar F, Ardeshir F (2023) Report of six plant parasitic nematodes from the orchards of Rafsanjan region, Kerman Province, Iran. Plant Pathology Science 12(2):41-52.

Introduction: In the suburban area of Rafsanjan city in Kerman Province, Iran, there are many orchards infested with plant parasitic nematodes. Therefore, it was necessary to identify the plant parasitic nematodes in the orchards of this region. Materials and Methods: In 2018 and 2019, some soil samples were taken around the roots of apricot, peach, pomegranate, apple, cherry and persimmon trees in this area. Nematodes were extracted by two methods, tray and sieve-centrifuge, and after fixation, they were transferred to pure glycerin. Permanent slides were examined with a bright field microscope and extracted nematodes were identified using diagnostic keys and original descriptions. Results: Seven nematodes from the infraorder Tylenchomorpha, belonging to five families including: Tylenchidae, Pratylenchidae, Tylenchulidae, Criconematidae and Anguinidae were identified. Root-lesion nematode (Pratylenchus penetrans), pin-nematode (Paratylenchus neoamblycephalus) and Criconematid (Mesocriconema xenoplax) were the most important plant parasitic nematodes in fruit orchards of this region. Conclusion: Due to the presence of some important and damaging nematodes in the orchards of Rafsanjan, it is recommended to implement appropriate management methods and monitor the population of important plant parasitic nematodes.

Root-lesion and cyst nematodes of vegetable and cucurbits fields in the suburbs of Rumeshkan city, Lorestan province, Iran

Kourosh Azizi

Yarahmadi F, Darvishnia M, Azizi K (2023) Root-lesion and cyst nematodes of vegetable and cucurbits fields in the suburbs of Rumeshkan city, Lorestan province, Iran. Plant Pathology Science 12(2):53-65.

Introduction: Root lesions and cyst nematodes can cause serious damage and loss in vegetable and squash production. This research aimed to identify these important plant parasitic nematodes in the fields of these plants in the suburbs of Rumeshkan city, Lorestan province, Iran. Materials and Methods: Forty-five soil and root samples were collected from vegetable and squash fields in the region, in 2021. The nematodes were extracted using the tray method and fixed using the modified de Grisse method and transferred to glycerol. After the permanent microscopic slides were prepared, the morphological characteristics of each nematode were examined using a bright-field microscope equipped with a digital camera and then identified using valid keys. Results: The lesion nematodes were identified as Pratylenchus speijeri, P. neglectus and P. thornei and the cyst nematode as Heterodera schachtii. This is the first report and description of P. speijeri from Iran and also the first report of H. schachtii from lettuce in Iran. Conclusion: Due to the presence of these important plant parasitic nematodes on these plants in this region, appropriate management practices need to be implemented.

Black scorch disease of date palm

Azadeh Goudarzi

Goudarzi A (2023) Black scorch disease of date palm. Plant Pathology Science 12(2):66-75.

Black scorch disease is considered one of the important and damaging diseases of date palm in many regions of the world, including Oman, Iraq, Qatar, Saudi Arabia, Kuwait, and the United Arab Emirates. The disease was first reported in Iran in 2014 from Tabas in South Khorasan Province, and in the following years, symptoms of the disease were observed scattered in Kerman, Hormozgan, Fars and Bushehr provinces. Two fungi, Thielaviopsis paradoxa and T. radicicola, are known as causal agents of the disease. Disease symptoms include tissue dieback, wilting, canopy bowing, terminal meristem rot, and tree dieback. The disease is commonly observed on trees suffering from environmental stress, particularly salt and drought stress. Although the susceptibility of different cultivars to the disease varies, the disease has been reported in 21 date palm cultivars worldwide to date. This article describes integrated disease management methods, including preventing diseases from entering the area, preventing damage to date palms, adhering to plant health principles, managing environmental stress, and proper ventilation in the grove, as well as biological and chemical control.

Reaction of eight luffa genotypes to damping-off disease

Mahdi Pirnia

Delaramifar M, Pirnia M, Keykhasaber M, Sarani SA, Khajeh H (2023) Reaction of eight luffa genotypes to damping-off disease. Plant Pathology Science 12(2):76-85.

Introduction: Damping-off caused by Pythium aphanidermatum is one of the major diseases of luffa. Identifying and planting of resistant varieties is an environmentally friendly solution for integrated disease management. This study was conducted to determine the reaction of eight native and non-native luffa genotypes to the disease. Materials and Methods: The pathogen (Pythium aphanidermatum IRAN597C) was obtained from the collection of fungi of the Iranian Institute of Plant Protection Researches. It was inoculated into seedlings of eight luffa genotypes. After the appearance of yellowing symptoms and seedling death, the disease index (DI) and the area under the disease progression curve (AUDPC) were calculated for each genotype. Koch's postulates were carried out to prove pathogenicity and the pathogen was isolated from diseased seedlings. Then, for molecular confirmation of the pathogen, ITS-rDNA sequencing was used. Results: The sequencing of the ITS-rDNA region of the pathogen showed a phylogenetic affinity of 99% with other isolates of P. aphanidermatum. According to the DI, the northern large and the long luffa genotypes were grouped as sensitive genotypes, and other genotypes including northern black seed, northern white seed, toori, Afghani, grooved and Brazilian were grouped as resistant genotypes. Based on the AUDPC, the northern black seed, and northern white seed genotypes showed the lowest level, toori, grooved, Afghani and Brazilian genotypes showed the medium level, and northern large and long luffa genotypes showed the highest AUDPC level. Conclusion: Considering the low values of the DI and AUDPC in the northern black seed and northern white seed genotypes, planting these two genotypes is suggested for management of the disease in luffa.

First report of Proleptonchus brevisaccus (Nematoda: Leptonchida) from Iran

Habibeh Jabbari

Jabbari H, Niknam G, Fallahi A(2023) First report of Proleptonchus brevisaccus (Nematoda: Leptonchida) from Iran. Plant Pathology Science 12(2):86-94.
Abstract: Nematodes are vermiform, with wide host range and geographical distribution, diverse and species-rich multicellular animals, which form a separate phylum in the kingdom of animals with the ability of living and surviving in all habitats. In order to identification of nematodes fauna of Astara- Mishe Sui forest – Gilan province, Iran, several soil samples were collected from sandy areas around a local river during 2014. The nematodes were extracted from samples by usual methods of nematology and after killing and fixing the nematodes were transferred to pure glycerin. Permanent microscopic slides of the nematodes were prepared and their morphological and morphometric characteristics examined using an optical microscope. Among the different feeding groups of nematodes, a population of the family Leptonchidae and the genus Proleptonchus was also obtained. The main character of the genus is having a flask-shaped cheilostome. Using valid references and identification keys, the population was identified as P. brevisaccus. This species belongs to the members of the genus that have short post vulval sac. Based on available literature, P. brevisaccus is a new record for the nematode fauna of Iran and its male is reported and described for the first time.

Occurrence of jujube brown spot disease in Iran

Fariba Ghaderi

Ghaderi F, Mohammadi H (2023) Occurrence of jujube brown spot disease in Iran. Plant Pathology Science 12(2):95-104.

Jujube tree has a natural distribution in tropical and sub-tropical regions of Asia. Symptoms of brown-to-black spots on leaves, and fruits, and twigs blight were observed in the hills of the suburbs of Nurabad County, Fars Province, Iran, in 2022. This research was conducted to identify the cause of this disease based on morphological and genetic characteristics. The diseased leaves and branches of the neighboring trees in this area were sampled. The pathogen was isolated and purified after surface disinfection of disease tissues on potato/dextrose/agar medium. Its morphological characteristics were studied and the fungus Nothophoma quercina was identified. Phylogenetic analysis base on the comparison of beta-tubulin (tub2), and ITS-rDNA genes sequences, with related fungi in NCBI Gen Bank, confirmed the of N. quercina species. Its pathogenicity was proved on the side cut jujube branches based on Koch's postulates in vitro. This is the first report of brown spot and twigs blight of the jujube trees caused by N. quercina in Iran.

Effect of temperature and culture medium on the growth and sporulation of eight Trichoderma species

Eidi Bazgir

Mirzaeipour Z, Bazgir E, Zafari D, Darvishnia M (2023) Effect of temperature and culture medium on the growth and sporulation of eight Trichoderma species. Plant Pathology Science 12(2):105-116. DOI: https://doi.org/10.2982/PPS.12.2.105

Trichoderma species are important agents of biological control of soil-borne plant pathogens. The growth and reproduction of these fungi are influenced by the culture medium and temperature. This study was conducted to determine the effect of temperature and culture medium on the growth and sporulation of Trichoderma species. Ten isolates of Trichoderma species were isolated from agricultural soils of different regions of Lorestan Province, Iran. The study of morphological characteristics and sequencing of ITS-rDNA, and tef1α gene regions showed that they are belong to eight species of Trichoderma. Investigating the effect of four types of culture medium and five temperatures to determine optimum culture medium and temperature for the growth and reproduction of these fungi, showed that the Potato/Dextrose/Agar (PDA) medium is the best, and the temperature of 20 to 30 degrees Celsius is optimal for the growth and reproduction of these fungi. Evaluation of their ability to inhibit the growth of the soil-borne plant pathogenic fungus Rhizoctonia solani in vitro, showed that T. harzianum LT8 has the most inhibition ability. Therefore, this isolate can be used as a potential biocontrol agent for this plant pathogenic fungus in future research.

Anthracnose disease of citrus

Azadeh Goudarzi

Goudarzi A (2023) Anthracnose disease of citrus. Plant Pathology Science 12(2):117-129.

Colletotrichum species are the causal agents of diseases including leaf spots, fruit rots and dieback in a wide range of plant hosts such as citrus, banana, strawberry, avocado, papaya, mango and apple. In citrus, important diseases including anthracnose, post harvest anthracnose, key lime anthracnose and postbloom fruit drop are caused by different species of Colletotrichum which are of the major limitations of citrus production in many citrus producing countries worldwide. Colletotrichum gloeosporioides has been identified as the main cause of citrus anthracnose. The disease symptoms include dieback of branches and twigs, leaf spot, fruit rot and abscission of leaves and small fruits. In the case of epidemic occurrence, the damage caused by the disease on different species and cultivars of citrus is very significant. The economic losses caused by the disease is mainly related to damage to the vegetative parts of citrus trees, as well as decay and reduction of market value of the fruits. So far, citrus anthracnose and postharvest anthracnose caused by C. gloeosporioides, C. fructicola, C. siamense, C. karstii and C. novae-zelandiae have been reported from Iran. In addition, dieback and postbloom fruit drop caused by C. gloeosporioides are of the common challenges of citrus production in the north of the country. Sanitation, management of irrigation and nutrition, control of pests, diseases and weeds and use of chemical fungicides, especially strobilurins, are effective approaches of the disease management. In order to prevent the emergence of resistant populations of the causal agents, the use of fungicides should be carried out with periodicity.

Defense responses by nitric oxide in plant-pathogen interaction

Saeedeh Dehghanpour Farashah

Dehghanpour Farashah S (2023) Defense responses by nitric oxide in plant-pathogen interaction. Plant Pathology Science 12(2):130-142.

The control of diseases in agriculture often relies on pesticides and chemical fertilizers, which negatively affect the rhizosphere natural microflora and ecosystem balance. Today, researchers are looking to replace these chemicals with other environment friendly agents to improve agricultural production and control plant pathogens. Research on the interaction of nitric oxide (NO) with plant pathogens has shown that NO is a key messenger in the response of plants to biotic and abiotic stresses. Due to the role of NO in the regulation of plant defense genes, especially through programmed cell death, it has attracted the attention of many plant pathologists. Although NO plays an important role in the hypersensitive reaction in response to various biotic and abiotic stresses, it has been found that NO also plays a role in regulating the expression of genes related to non-specific resistance. In this review, the role of nitric oxide in plant-pathogens interaction has been investigated.