Biology and Management of Nematodes in potato

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Phenotypic and molecular characterization of potato germplasm for potato cyst nematode resistance

Not AvailablePotato cyst nematode (PCN) is considered to be the most devastating pest causing major yield losses in potato worldwide. Resistant potato cultivars would be the most effective strategy to control PCN however, they may not posses enough resistance to all pathotypes of PCN. Therefore breeding programme should focus on developing varieties with horizontal resistance which can be achieved by using parental lines with multiple resistant genes. Hence, the present study was conducted to characterize the phenotypic and genotypic resistance of parental lines against PCN and also an attempt was made to find out the pollen viability of the parental lines to improve the breeding efficiency. Sixty six genotypes were screened phenotypically as well as genotypically against PCN. Out of which, 54 lines were found phenotypically resistant to G. rostochiensis, 48 to G. pallida and 44 to both the species of PCN. The same set of parental lines was also validated using linked molecular markers. In molecular characterization, the markers linked with H1 gene (TG689 and 57R) were found in majority of the parental lines screened. Marker SPUD 1636 linked to GPa5 QTL was positive for three genotypes whereas HC marker (GPaVvrn QTL) was positive for 30 parental lines. TG432 linked to Grp1 gene is positive for 27 parental lines whereas the marker Gro 1-4-1 is not amplified in any of the screened parental lines. Pollen viability of parental lines varied from 15.8 to 93.6%. The results of the study will facilitate breeding of novel resistant varieties by efficient selection of ideal male parent with good pollen potential and multiple resistance to several PCN pathotypes

Loop-Mediated Isothermal Amplification (Lamp) Assay: Principles and Applications

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Egyptian Journal of Biological Pest Control

Not AvailableRoot-knot nematode (RKN), Meloidogyne incognita, is one of the most lingering and difficult to manage pest of black pepper in India. The options for controlling RKN are becoming increasingly limited due to the potential risk involved in environmental and health hazards. Biological control using Pasteuria is one of the most effective and efficient ways of nematode management. Pasteuria spp. are obligate parasites of plant-parasitic nematodes and completely inhibit their fecundity. There is also a tremendous opportunity for the discovery of native strains adapted to local environmental conditions and nematode species. Therefore, in the present study, efforts were made to isolate the native strain of Pasteuria from the fields of black pepper. Random sampling was done from black pepper-growing areas of Kerala and Karnataka states of India. Out of 39 samples, Pasteuria was found in 8 samples from the fields of ICAR-IISR, Kozhikode, Kerala, India. The host range study revealed that the identified Pasteuria strain was very specific to M. incognita and completed its life cycle in RKN. Infected females laid no eggs or egg masses; thus, Pasteuria prohibited the total fecundity of the nematodes. The Pasteuria strain was named as IISR-MiP for it was found in the fields of ICAR-IISR and its specificity towards M. incognita. The average size of the identified Pasteuria strain IISR-MiP endospore was 2.75??m. Light as well as scanning electron micrographs revealed 3 types of endospore attachments viz., conventional, inverted, and sideways. Further, it was found that endospores attached to the nematode cuticle in the maximum number in a conventional type of attachment (87.62%), followed by inverted (6.55%) and sideways attachments (5.82%). The inverted and sideways attachments were unique to the biology of Meloidogyne-Pasteuria interactions, indicating the presence of collagen-like fibres on the entire surface of Pasteuria endospores. Pasteuria strain IISR-MiP had the potential biocontrol capabilities and provided an opportunity for its evaluation against M. incognita on black pepper under field conditions

Chaetomium globosum KPC3: An antagonistic fungus against the potato cyst nematode, Globodera rostochiensis

Not AvailableThe potato cyst nematode (Globodera rostochiensis) is one of the most economically important pests of potato (Solanum tuberosum L.), causing significant economic losses worldwide. The identification of biocontrol agents for the sustainable management of G. rostochiensis is crucial. In this study, a potential biocontrol agent, Chaetomium globosum KPC3, was identified based on sequence analysis of the DNA internal transcribed spacer (ITS) region, the translation elongation factor 1-alpha (TEF1-?) gene, and the second largest subunit of the RNA polymerase II (RPB2) gene. The pathogenicity test of C. globosum KPC3 against cysts and second-stage juveniles (J2s) revealed that fungus mycelium fully parasitized the cyst after 72 h of incubation. The fungus was also capable of parasitizing the eggs inside the cysts. The culture filtrate of C. globosum KPC3 caused 98.75% mortality in J2s of G. rostochiensis after 72 h of incubation. The pot experiments showed that the combined application of C. globosum KPC3 as a tuber treatment at a rate of 1 lit kg-1 of tubers and a soil application at a rate of 500 ml kg-1 of farm yard manure (FYM) resulted in significantly lesser reproduction of G. rostochiensis compared to the rest of the treatments. Altogether, C. globosum KPC3 has the potential to be used as a biocontrol agent against G. rostochiensis and can be successfully implemented in integrated pest management programs

RNA-Seq of Cyst Nematode Infestation of Potato (<i>Solanum tuberosum</i> L.): A Comparative Transcriptome Analysis of Resistant and Susceptible Cultivars

Potato (Solanum tuberosum L.) is an important food crop worldwide, and potato cyst nematodes (PCNs) are among the most serious pests. The identification of disease resistance genes and molecular markers for PCN infestation can aid in crop improvement research programs against PCN infestation. In the present study, we used high-throughput RNA sequencing to investigate the comprehensive resistance mechanisms induced by PCN infestation in the resistant cultivar Kufri Swarna and the susceptible cultivar Kufri Jyoti. PCN infestation induced 791 differentially expressed genes in resistant cultivar Kufri Swarna, comprising 438 upregulated and 353 downregulated genes. In susceptible cultivar Kufri Jyoti, 2225 differentially expressed genes were induced, comprising 1247 upregulated and 978 downregulated genes. We identified several disease resistance genes (KIN) and transcription factors (WRKY, HMG, and MYB) that were upregulated in resistant Kufri Swarna. The differentially expressed genes from several enriched KEGG pathways, including MAPK signaling, contributed to the disease resistance in Kufri Swarna. Functional network analysis showed that several cell wall biogenesis genes were induced in Kufri Swarna in response to infestation. This is the first study to identify underlying resistance mechanisms against PCN and host interaction in Indian potato varieties

Selective Isolation and Characterization of Phytophthora infestans from Potatoes Using Rye Agar Media in India

Phytophthora infestans is a pathogen that causes late blight, a major disease of potatoes. The isolation of P. infestans from infected potato plants using agar media has been challenging. This study investigated the use of Rye A and Rye B agar media for the isolation of P. infestans from infected potato tubers collected from the Nilgiris district of Tamil Nadu during 2022. The media were evaluated for hyphal growth, sporangial production, oospore formation, and long-term storage of P. infestans. Phenotypic diagnosis based on cultural and morphological characteristics confirmed the identity of P. infestans. The results were confirmed by a molecular identification test using primers specific to P. infestans. Pathogenicity tests were carried out to assess the virulence of the isolates. This study provides a useful protocol for the selective isolation and characterization of P. infestans, the potato late blight pathogen