Molecular and morphological characterization of Globodera rostochiensis (Wollenweber, 1923) Skarbilovich, 1959 from Egypt

The golden potato cyst nematode, Globodera rostochiensis (Wollenweber, 1923) Skarbilovich (1959) is a damaging soilborne quarantine pest of Solanum tuberosum (potato) and other solanaceous crops worldwide. In spring of 2021 a survey was conducted in area of Abo El Matamer, Bahera governorates in Egypt. Soil samples were taken in zigzag pattern throughout 65 acres of potato cultivated land and processed in Nematology lab, Fayoum University, Egypt. In June 2021, two hundred soil samples were collected from nearby areas to evaluate the distribution of this potato cyst nematode in other cultivated land located in area of first infection but fortunately the golden potato cyst nematode was not detected from neighboring locations. The nematode species was identified by both morphological and molecular means as Globodera rostochiensis. To our knowledge this is the first molecular and morphological characterization of G. rostochiensis from Egypt.

Assessment of resistance of potato hybrids from the Russian Potato Research Center’s collection to Globodera rostochiensis

The potato cyst nematodes (PCN) Globodera rostochiensis and Globodera pallida are the most common pests feeding on potato roots. These pests have an aggressive distribution dynamic and bring a lot of damage to yield. The study presents results of comprehensively test new potato genotypes for resistance to the golden potato nematode (Globodera rostochiensis), for its further use in breeding and the creation of economically valuable resistant varieties. Almost half of the samples showed laboratory resistance to golden potato nematode, the rest were susceptible. 26 samples have shown the presence of two molecular markers (N146, N19), indicating the presence of H1 gene. Almost all samples showed a correspondence between laboratory resistance and the presence of H1 gene markers.

A Survey of Globodera Rostochiensis on Potato Crops in Himachal Pradesh; Occurrence and Detection.

A survey was carried out to estimate the frequency and occurrence of potato cyst nematode (PCN) in potato cultivating fields in different districts of Himachal Pradesh. A total of 109 composite soil samples were collected from 5 districts of Himachal Pradesh, India. Nematode cysts were extracted from the soil using standard procedure. The population density and percentage of occurrence of cyst nematode were calculated. According to the results district, Mandi had the highest PCN cyst population density, and the percentage of occurrence is 100%. District Kangra had the least PCN cyst population density and the percentage of occurrence is 66.6%. This survey showed the occurrence Globodera rostochiensis district-wise. The collected cysts were identified by morphological and molecular techniques, up to species level based on nucleotide homology and phylogenetic analysis. According to morphometrics distance between the vulva and anus is very less (65.69 ±22.2) µm. The outcome sequences are showed 95-99.05% similarity with sequence I.D KJ636272.1 from the Netherlands. This survey indicates that PCN Globodera rostochiensis were widely distributed in the potato cultivating fields of Himachal Pradesh. The present study helped determine the distribution of PCN in the soil and species dominance in particular areas. Hence, it helps design different strategies against PCN management.

Comparative genomics of two inbred lines of the potato cyst nematode Globodera rostochiensis reveals disparate effector family-specific diversification patterns

Background Potato cyst nematodes belong to the most harmful pathogens in potato, and durable management of these parasites largely depends on host-plant resistances. These resistances are pathotype specific. The current Globodera rostochiensis pathotype scheme that defines five pathotypes (Ro1 - Ro5) is both fundamentally and practically of limited value. Hence, resistant potato varieties are used worldwide in a poorly informed manner. Results We generated two novel reference genomes of G. rostochiensis inbred lines derived from a Ro1 and a Ro5 population. These genome sequences comprise 173 and 189 scaffolds respectively, marking a ≈ 24-fold reduction in fragmentation as compared to the current reference genome. We provide copy number variations for 19 effector families. Four dorsal gland effector families were investigated in more detail. SPRYSECs, known to be implicated in plant defence suppression, constitute by far the most diversified family studied herein with 60 and 99 variants in Ro1 and Ro5 distributed over 18 and 26 scaffolds. In contrast, CLEs, effectors involved in feeding site induction, show strong physical clustering. The 10 and 16 variants cluster on respectively 2 and 1 scaffolds. Given that pathotypes are defined by their effectoromes, we pinpoint the disparate nature of the contributing effector families in terms of sequence diversification and loss and gain of variants. Conclusions Two novel reference genomes allow for nearly complete inventories of effector diversification and physical organisation within and between pathotypes. Combined with insights we provide on effector family-specific diversification patterns, this constitutes a basis for an effectorome-based virulence scheme for this notorious pathogen.