Chaetomium globosum KPC3: An Antagonistic Fungus Against the Potato Cyst Nematode, Globodera rostochiensis.

The 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-α) 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.

Kaolinite nanoclay-shielded dsRNA drenching for management of Globodera pallida: An environmentally friendly pest management approach.

Globodera pallida, an obligate sedentary endoparasite, is a major economic pest that causes substantial potato yield losses. This research aimed to study the effects of gene silencing of three FMRFamide-like peptides (FLPs) genes to reduce G. pallida infestation on potato plants by using kaolinite nanoclay as a carrier to deliver dsRNAs via drenching. A dsRNA dosage of 2.0 mg/ml silenced flp-32c by 89.5%, flp-32p by 94.6%, and flp-2 by 94.3%. J2s incubated for 5 and 10 h showed no phenotypic changes. However, J2s of G. pallida efficiently uptake dsRNA of all targeted genes after 15 h of incubation. On the other hand, J2s that had been kept for 24 h had a rigid and straight appearance. Under fluorescence microscopy, all dsRNA-treated nematodes showed fluorescein isothiocyanate (FITC) signals in the mouth, nervous system, and digestive system. The untreated population of J2s did not show any FITC signals and was mobile as usual. The drenching of potato cultivar Kufri Jyoti with the dsRNA-kaolinite formulations induced deformation and premature death of J2s, compared with untreated J2s that entered J3 or J4 stages. This study validates that the nanocarrier-delivered RNAi system could be employed effectively to manage G. pallida infestations.

Development and evaluation of loop-mediated isothermal amplification assay for rapid and sensitive detection of potato cyst nematode, Globodera pallida from soil.

Potato cyst nematodes, Globodera pallida and G. rostochiensis, are economically important and difficult to manage pests of the potato crop. The cyst of both the species looks similar and it is difficult to differentiate once it turns brown upon maturity. Early detection of the PCN at the species level is crucial to avoid its further spread and for adopting the appropriate management strategies. Therefore, in the present study, highly specific and sensitive loop-mediated isothermal amplification (LAMP) assay was developed to amplify mitochondrial-Sequence Characterized Amplified Region (SCAR) sequence of potato cyst nematode, G. pallida. The LAMP assay was completed within a shorter incubation period of 60 min at 60 °C followed by the reaction termination at 80 °C for 5 min. The developed LAMP assay exhibited high specificity for G. pallida and did not detect any other species including its sibling species, G. rostochiensis. In sensitivity tests, the assay detected G. pallida at 1000 times less DNA concentration (10 fg/µl) as compared to conventional PCR (10 pg/µl). In addition to this, the developed LAMP assay was tested for the detection of G. pallida directly from the soil samples, and even a single cyst mixed with soil was successfully detected by the developed assay. Moreover, the utility of low-cost instruments like hot water bath was also demonstrated for the detection of G. pallida from the soil. The developed LAMP is a rapid, highly specific, sensitive, and cost-effective technique for the species-specific detection of G. pallida. The developed assay will facilitate the rapid detection of G. pallida at quarantine stations as well as from the fields which will help to stop its further spread in new areas and also to devise effective management strategies for sustainable potato production. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03542-x.

A new record of Asia II 5 genetic group of Bemisia tabaci (Gennadius) in the major potato growing areas of India and its relationship with tomato leaf curl New Delhi virus infecting potato.

The whitefly, Bemisia tabaci (Gennadius), is responsible for significant yield losses in many crops, including potato, by sucking the phloem sap and transmitting a number of plant viruses. B. tabaci is a complex of cryptic species which is commonly designated as genetic groups. The B. tabaci genetic groups differ biologically with respect to host plant preference, insecticidal resistance, reproduction capacity, and ability to transmit begomoviruses. Therefore, understanding genetic variation among populations is important for establishing crop-specific distribution profile and management. We sequenced the mitochondrial cytochrome oxidase I (mtCOI) gene of B. tabaci collected from major potato growing areas of India. BLAST analysis of the 24 mtCOI sequences with reference Gene Bank sequences revealed four B. tabaci genetic groups prevailing in this region. mtCOI analysis exhibited the presence of Asia II 1, Asia II 5, Asia 1, and MEAM1 B. tabaci genetic groups. Our study highlighted that a new genetic group Asia II 5 has been detected in Indo-Gangetic Plains. Further virus-vector relationship study of ToLCNDV with Asia II 5 B. tabaci revealed that females are efficient vector of this virus as compared to males. This behavior of females might be due to their ability to acquire more virus titer than males. This study will help in better understanding of whitefly genetic group mediated virus diseases.