Biofertilizers in the control of Pratylenchus brachyurus in soybean crop

Nematodes are of great importance in soybean cultivation, especially the Pratylenchus brachyurus known as root lesion nematode. Its attack on plant roots causes less efficiency in the absorption of water and nutrients, in addition to damaging the plant's development. There is still no fully efficient method to control this phytopathogen, however, some products are available on the market, including biological control. Thus, the aim of this study was to evaluate commercial biological products in the efficiency of reducing the nematode population in soybean crop in Goiás, Brazil. The design was completely randomized in a 2x4 factorial scheme, the first factor being two soybean genotypes (Brasmax Bônus and Nidera NS 8383) and the second factor the treatments consisting of different dosages in an association of three commercial products: No-Estio®, Bio-fertility® and Radic®. The treatments used were: T1 control - without application of the products; T2 half the recommended dose; T3 the recommended dose and T4 a dose and a half that recommended by the manufacturer. Plant evaluation was carried out after 75 days of nematode inoculation. The results obtained showed that both cultivars hosted P. brachyurus, however, the treatments using the products had a lower population density of this nematode. It was concluded that the two soybean cultivars are hosts of Pratylenchus brachyurus. The agronomic character plant height was more affected when there was no application by the biological method. The association of No-Estio®, Bio-fertility® and Radic® products reduced the population density of nematodes in infected plants.

Identification and pathogenicity of Pratylenchus scribneri on tomato in Sichuan Province of People's Republic of China

Root-lesion nematodes (Pratylenchus spp.) are a group of economically important pathogens that have caused serious economic losses in many crops. In 2019, root-lesion nematodes were recovered from tomato (Solanum lycopersicum) root samples collected from Sichuan Province, People's Republic of China (PRC). Extracted nematodes were disinfected, and one individual female was cultured on a carrot disc for propagation at 25 °C by parthenogenesis and designated the SC isolate. Afterwards, the isolate was identified on the basis of morphometric and molecular markers. Both morphometric characters and molecular analysis of the internal transcribed spacer region gene (ITS) of ribosomal DNA, the D2-D3 expansion region of the 28S rDNA gene and the mitochondrial cytochrome oxidase I (mtDNA-COI) gene revealed that the species of root-lesion nematode was Pratylenchus scribneri. The Bayesian tree inferred from the ITS rDNA, 28S rDNA and mtDNA-COI gene sequences also showed that this isolate formed a highly supported clade with other P. scribneri isolates. The pathogenicity of the root-lesion nematode SC isolate on tomato was assessed, showing that tomato was a suitable host for P. scribneri. To the best of our knowledge, this is the first report of P. scribneri on tomato in Sichuan Province, PRC. These are also the first molecular data obtained from P. scribneri on tomato in the PRC, and the pathogenicity of P. scribneri to tomato was studied for the first time. This study provides scientific data for the detection, identification and control of tomato root-lesion nematode disease.

Molecular and morphological characterization of the root -lesion nematode, Pratylenchus neglectus, on corn from Henan Province of China

Summary Root-lesion nematodes, Pratylenchus spp., are economically important pathogens because of their detrimental and economic impact on a wide range of crops. In August 2018, two samples of both roots and rhizosphere soil were collected from a corn field in Liangyuanqu of Shangqiu city, Henan Province, China. Root-lesion nematodes were recovered from the roots and soil samples using the modified Baermann funnel extraction method. Both the morphological characters and molecular analysis of the internal transcribed spacer (ITS) and D2-D3 expansion region of 28S ribosomal RNA sequences confirmed that the root-lesion nematode population collected from corn in this study was P. neglectus. Phylogenetic analyses showed that this isolate formed a highly supported clade with other P. neglectus isolates. To the best of our knowledge, this is the first report of P. neglectus on corn in Henan Province of China. This study reports the first partial sequences of 28S D2-D3 region of P. neglectus on corn in China. Due to the great harmfulness of root-lesion nematodes to corn, care should be taken to prevent the spread of P. neglectus to other regions in China. At the same time, further study on the biological characteristics of P. neglectus is needed, which will be helpful to develop corresponding management and control strategies.

Discovery of Root-Lesion Nematode (Pratylenchus scribneri) on Corn in Hainan Province of China

Corn (Zea mays L.) is a very important cereal crop and serves as food, feed, and industrial material (Liu et al. 2016). The root-lesion nematode (RLN) is considered one of the most important plant-parasitic nematodes and can cause economic losses in agriculture worldwide (Jones et al. 2013). In January 2020, five samples were collected from a corn field in Lingshui Lizu Autonomous County, Hainan Province, China. The collected corn plants (cv. Denghai 685) were growing poorly and roots showed distinct lesions and rot. Corn fields with symptoms of stunted plants, and brown lesions on roots were widespread. This corn disease was severe in Lingshui Lizu Autonomous County. RLN were extracted from soil samples by the modified Baermann funnel (Hooper et al. 2005). All the samples contained RLN ranging from 9 to 82 (average 39) RLN per 100 cm3 of soil and 113 to 257 (average 194) RLN per 5 g roots. The extracted RLN were sterilized and cultured on carrot disks at 25°C for 90 days. Afterwards, seeds of corn (cv. Denghai 685) were sown in pots containing 1.8 liters of sterilized soil. Eight plants, one per pot, were infested with 1,000 RLN, eight pots of noninfested corn plants were used as controls, and plants were kept in a greenhouse at 25°C. At 75 days after inoculation, symptoms were like those initially observed in corn fields, whereas no symptoms were observed in the control plants. Nematodes in the soil and roots were extracted using the same method as previously described (Hooper et al. 2005). The average number of RLN per pot was approximately 4,250 in soil and 820 in roots, the reproduction factor (final number of nematodes/initial number of nematodes) was 5.07, no RLN were found in the control. The experiment was conducted twice. The morphological and molecular studies of RLN were examined to confirm species identification. The main morphological measurements of adult females (n = 15) included body length = 526.0 μm ± 17.1 (standard error) (range = 498.0 to 560.5 μm), stylet = 16.0 μm ± 0.3 (15.5 to 16.5 μm), tail length = 29.0 μm ± 1.5 (26.5 to 31.0 μm), a = 23.6 ± 0.6 (22.6 to 24.4), b = 5.6 ± 0.3 (5.2 to 6.0), c = 18.3 ± 0.9 (16.4 to 19.7), V = 78.2% ± 0.6 (77.4 to 79.2%), lip region with two annules. No males were found in the samples. This population was identified as Pratylenchus scribneri, based on the morphological characters (Castillo and Vovlas, 2007). DNA was isolated from individual nematodes followed by proteinase K-based lysis (Wang et al. 2011). The D2/D3 expansion region of the 28S rRNA gene, rDNA-internal transcribed spacer (ITS) region, and mitochondrial cytochrome oxidase I (mtDNA-COI) gene were amplified with primers D2A/-D3B (De Ley et al. 1999), TW81/ AB28 (Vovlas et al. 2011) and JB3/ JB5 (Liu et al. 2018), respectively. The PCR products were purified and ligated into pJET 1.2/blunt cloning vectors and transformed to Escherichia coli strain DH5α, and then sequenced. The obtained 28S rRNA gene D2/D3 region sequences (785bp), ITS sequences (886 bp) and mtDNA-COI (447bp) in this study were submitted to GenBank. The D2/D3 region of the 28S rRNA sequences of the RLN collected in Lingshui (GenBank accession no. MZ701843) showed 99.75% identity with P. scribneri sequences available in the GenBank (KX842628 and KX842625). The ITS sequences of the RLN collected in this study (MZ701842) showed the highest identity of 97.06% with P. scribneri sequences available in the GenBank (KX842626). The mtDNA-COI sequences of the RLN collected in this study (OK040228) showed 100% identity with P. scribneri (MN366409). Both morphological and molecular data confirmed the identity of P. scribneri. P. scribneri has been reported on corn in Inner Mongolia, Hebei, Shanxi, Shandong, Henan, Jiangsu, and Liaoning provinces of China (Li et al. 2019). As far as we know, this is the first report of P. scribneri on corn in Hainan Province, China. Since the RLN can cause considerable damage to corn, strategic measures should be taken to prevent the spread of P. scribneri to other regions in China.

Transcriptome analysis reveals key genes associated with root-lesion nematode Pratylenchus thornei resistance in chickpea

The root-lesion nematode, Pratylenchus thornei, is one of the major plant-parasitic nematode species causing significant yield losses in chickpea (Cicer arietinum). In order to identify the underlying mechanisms of resistance to P. thornei, the transcriptomes of control and inoculated roots of three chickpea genotypes viz. D05253 > F3TMWR2AB001 (resistant advanced breeding line), PBA HatTrick (moderately resistant cultivar), and Kyabra (susceptible cultivar) were studied at 20 and 50 days post inoculation using the RNA-seq approach. On analyzing the 633.3 million reads generated, 962 differentially expressed genes (DEGs) were identified. Comparative analysis revealed that the majority of DEGs upregulated in the resistant genotype were downregulated in the moderately resistant and susceptible genotypes. Transcription factor families WRKY and bZIP were uniquely expressed in the resistant genotype. The genes Cysteine-rich receptor-like protein kinase 10, Protein lifeguard-like, Protein detoxification, Bidirectional sugar transporter Sugars Will Eventually be Exported Transporters1 (SWEET1), and Subtilisin-like protease were found to play cross-functional roles in the resistant chickpea genotype against P. thornei. The identified candidate genes for resistance to P. thornei in chickpea can be explored further to develop markers and accelerate the introgression of P. thornei resistance into elite chickpea cultivars.

A survey of plant-parasitic nematodes in Illinois corn fields, 2018 and 2020

One hundred and forty-seven soil samples were collected from corn fields located within 63 Illinois counties during the 2018 and 2020 corn growing seasons. The soil samples were analyzed for frequency and population density of plant-parasitic nematodes. A total of 10 plant-parasitic nematode taxa were identified. Spiral nematode (Helicotylenchus spp.) was the most frequently observed nematode (frequency: 98.6%), followed by lesion nematode (Pratylenchus spp., 85.7%). Other taxa identified included cyst (Heteroderidae, 66.7%), stunt (Tylenchorhynchus spp., 33.3%), lance (Hoplolaimus spp., 29.9%), dagger (Xiphinema spp., 12.9%), pin (Paratylenchus spp., 12.2%), needle (Longidorus spp., 1.4%), stubby-root (Trichodoridae, 1.4%), and ring nematodes (Criconematidae, 0.7%). Nematodes with the greatest population densities included spiral (89 nematodes per 100 cm3 of soil), pin (36), and cyst nematodes (26). Among the 10 nematode taxa, 4.1%, 7.1%, and 2.3% of spiral, lesion, and lance nematodes positive samples exceeded estimated damage thresholds for corn for Illinois, respectively. Results from this survey will help the agricultural community with understanding pathogenic corn nematode populations in the state and prioritize research in this understudied area.

Planting Material of Enset (Ensete ventricosum), a Key Food Security Crop in Southwest Ethiopia, Is a Key Element in the Dissemination of Plant-Parasitic Nematode Infection

Enset (Ensete ventricosum), is a perennial herbaceous plant belonging to the family Musaceae, along with banana and plantain. Despite wild populations occurring in eastern, central and southern Africa, it is only in Ethiopia that the crop has been domesticated, where it is culturally and agriculturally symbolic as a food security crop. Although an under-researched orphan crop, enset serves as a staple food for about 20% of the Ethiopian population, comprising more than 20 million people, demonstrating its value in the country. Similar to banana and plantain, enset is heavily affected by plant-parasitic nematodes, with recent studies indicating record levels of infection by the root lesion nematode Pratylenchus goodeyi. Enset is propagated vegetatively using suckers that are purposely initiated from the mother corm. However, while banana and plantain suckers have proven to be a key source of nematode infection and spread, knowledge on the infection levels and role of enset suckers in nematode dissemination is lacking. Given the high levels of plant-parasitic nematodes reported in previous surveys, it is therefore speculated that planting material may act as a key source of nematode dissemination. To address this lack of information, we assessed enset planting material in four key enset growing zones in Ethiopia. A total of 340 enset sucker samples were collected from farmers and markets and analyzed for the presence of nematodes. Nematodes were extracted using a modified Baermann method over a period of 48 h. The root lesion nematode P. goodeyi was present in 100% of the samples, at various levels of infection. These conclusive results show that planting material is indeed a key source of nematode infection in enset, hence measures taken to ensure clean suckers for planting will certainly mitigate nematode infection and spread. The effect of nematode infection on yield and quality on enset remains to be investigated and would be a way forward to complement the nematode/disease studies conducted so far and add valuable knowledge to the current poorly known impact of pests and diseases.