Search Results (5)

Leaf parsley growth and productivity are often affected by pathogen infection. Root-knot nematodes of the genus Meloiogyne are common pathogens reported on leaf parsley. The response of leaf parsley to Meloidogyne species in tropical and subtropical regions is quite known, while in temperate regions, comparable information is still scarce. In this study, we evaluated the host status and response of three flat-leaf (Laica, Laura, Gigante d’Italia) and three curly-leaf (Grüne Perle, Orfeo, Sombre) parsley cultivars to Meloidogyne species from temperate regions, i.e., M. hapla, M. chitwoodi, and M. fallax, as well as to the southern root-knot nematode M. incognita. Evaluation was based on measuring plant biomass and nematode reproduction nine weeks after nematode inoculation. Our results showed that all four Meloidogyne species did not cause the reduction in leaf parsley growth under the given experimental conditions. Regarding the host status of leaf parsley cultivars for Meloidogyne, results were variable. All six parsley cultivars were found to be good hosts for M. hapla. Regarding M. chitwoodi, the host status could not be clarified properly; however, each cultivar allowed nematode reproduction at least in one experiment. For M. fallax, flat-leaf parsley turned out to be less susceptible than curly-leaf parsley; and for M. incognita, Orfeo, Laura, and Laica were classified as good hosts, Grüne Perle and Sombre as poor hosts, and Gigante d’Italia as a non-host. Amongst all tested cultivars, Gigante d’Italia was found to be the least susceptible cultivar due to its poor host status for M. chitwoodi and non-host status for M. fallax and M. incognita. Infection with M. hapla, M. chitwoodi, and M. incognita, but not with M. fallax, resulted in distinct gall formation on the roots of all six leaf parsley cultivars. Full article

Pest attacks on plants can substantially change plants’ volatile organic compounds (VOCs) emission profiles. Comparison of VOC emission profiles between non-infected/non-infested and infected/infested plants, as well as resistant and susceptible plant cultivars, may provide cues for a deeper understanding of plant-pest interactions and associated resistance. Furthermore, the identification of biomarkers—specific biogenic VOCs—associated with the resistance can serve as a non-destructive and rapid tool for phenotyping applications. This research aims to compare the VOCs emission profiles under diverse conditions to identify constitutive (also referred to as green VOCs) and induced (resulting from biotic/abiotic stress) VOCs released in potatoes and wheat. In the first study, wild potato Solanum bulbocastanum (accession# 22; SB22) was inoculated with Meloidogyne chitwoodi race 1 (Mc1), and Mc1 pathotype Roza (SB22 is resistant to Mc1 and susceptible to pathotype Roza), and VOCs emission profiles were collected using gas chromatography-flame ionization detection (GC-FID) at different time points. Similarly, in the second study, the VOCs emission profiles of resistant (‘Hollis’) and susceptible (‘Alturas’) wheat cultivars infested with Hessian fly insects were evaluated using the GC-FID system. In both studies, in addition to variable plant responses (susceptibility to pests), control treatments (non-inoculated or non-infested) were used to compare the VOCs emission profiles resulting from differences in stress conditions. The common VOC peaks (constitutive VOCs) between control and infected/infested samples, and unique VOC peaks (induced VOCs) presented only in infected/infested samples were analyzed. In the potato-nematode study, the highest unique peak was found two days after inoculation (DAI) for SB22 inoculated with Mc1 (resistance response). The most common VOC peaks in SB22 inoculated with both Mc1 and Roza were found at 5 and 10 DAI. In the wheat-insect study, only the Hollis showed unique VOC peaks. Interestingly, both cultivars released the same common VOCs between control and infected samples, with only a difference in VOC average peak intensity at 22.4 min retention time where the average intensity was 4.3 times higher in the infested samples of Hollis than infested samples of Alturas. These studies demonstrate the potential of plant VOCs to serve as a rapid phenotyping tool to assess resistance levels in different crops. Full article

Plant-parasitic nematodes (PPNs) are important pests that cause an estimated ten billion dollars of crop loss each year in the United States and over 100 billion dollars globally. The Animal and Plant Health Inspection Service (APHIS) within the U.S. Department of Agriculture maintains and updates the U.S. Regulated Plant Pest list. Currently, the number of PPNs regulated by APHIS includes more than 60 different species. This review focuses on the top ten most economically important regulated and emerging plant-parasitic nematodes and summarizes the diagnostics of morphological and some molecular features for distinguishing them. These ten major previously described nematode species are associated with various economically important crops from around the world. This review also includes their current distribution in the U.S. and a brief historical background and updated systematic position of these species. The species included in this review include three PPNs considered by the U.S. Department of Agriculture as invasive invertebrates Globodera pallida, Globodera rostochiensis, and Heterodera glycines; four regulated PPNs, namely Bursaphelenchus xylophilus, Meloidogyne fallax, Ditylenchus dipsaci, and Pratylenchus fallax; and the three emerging PPNs Meloidogyne chitwoodi, Meloidogyne enterolobii, and Litylenchus crenatae mccannii. Full article

Meloidogyne spp., commonly known as root-knot nematodes (RKN), are among the most economically damaging plant-parasitic nematodes to horticultural and field crops, mainly due to their pathogenic effect, worldwide distribution, and wide host range. RKN pest management relies on the use of commercial synthetic pesticides, such as broad-spectrum fumigants and nervous system toxins, which kill or disrupt the feeding or reproductive behavior of nematodes. These active chemicals can cause negative environmental and public health impacts and are feared to lead to resistance and immunity. As a sustainable alternative, the use of essential oils (EOs) as nematicides has shown great promise. These natural products are mostly biodegradable and subjected to less strict regulatory approval mechanisms for their exploration. The present work reviews the existing bibliography on the direct biological activity of EOs against RKNs. A total of 49 publications from 1995 to 2020 were identified to have reported on the anti-RKN activity of EOs. Plants from the Lamiaceae and Compositae families make up more than 50% of the source material for EO extraction. The highest activities were reported for EOs of the Monarda, Artemisia, Filipendula, and Satureja genus. These taxa show potential that can be further explored for highly active anti-RKN phytochemicals with practical applications in sustainable pest management strategies. Full article

The genus Eucalyptus (Myrtaceae) comprises more than 800 species, mostly native to Australia. Eucalyptus shoots’ essential oils (EOs) are well-known for their extremely high qualitative and quantitative variation in terpenes (mainly mono- and sesquiterpenes). These EOs have a wide range of uses, from the taxonomic characterization of populations based on the chemical profiling of EO chemotypes, to industrial applications, including pharmaceutical and agrochemical and in food and fragrances. In this study, we reviewed the available information concerning the chemical variability of EOs from Eucalyptus spp. assayed against nematodes. Among the most active EOs, those from E. globulus, E. staigeriana, and E. citriodora were most frequently used. EO chemical composition was mainly dominated by 1,8-cineole, limonene, p-cymene, citronellal, and piperitone in varying proportions. Nematicidal activity of Eucalyptus EOs was reported against animal parasitic nematodes, including gastrointestinal nematodes (e.g., Haemonchus contortus), plant parasitic nematodes, such as root-knot nematodes (e.g., Meloidogyne incognita and M. chitwoodi) or the pinewood nematode Bursapelenchus xylophilus, and the free-living nematode Caenorhabditis elegans. Correlation between EO qualitative and quantitative composition with its respective activity may provide valuable information on the nematicidal specificity of EOs. This knowledge can be useful for devising environmentally safer pest management strategies in the conservation of ecosystems biodiversity. Full article