scholarly journals Biology, Taxonomy, and Management of the Root-Knot Nematode (Meloidogyne incognita) in Sweet Potato

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Gebissa Yigezu Wendimu

Sweet potato is the seventh-ranked food crop produced after wheat, rice, maize, potato, barley, and cassava in the world. It is the most important root tuber crop in temperate, subtropical, and tropical areas of the world. It is grown for food, income-generating, and jobs for farmers and retailers. The important nutritional substances of sweet potatoes are ß-carotene and anthocyanins. However, the production and its valuable products are limited due to root-knot nematode parasitism. One of the most important destructive species of root-knot nematode to this crop is Meloidogyne incognita. The most destructive stage to sweet potato is at its second juvenile stage (J2). At this stage, it invades the roots and tubers of sweet potato highly in warm sandy soil conditions. It is an obligate plant-parasitic nematode. M. incognita caused significant yield loss to sweet potato in terms of quality, quantity, disturbing the process of photosynthesis and nutrient uptake through the formation of galling, establishing of its feeding sites, or induced galls that contain giant-feeding cells, and cracking of tubers and roots directly. It also reduces the market values of the infected tuber of sweet potato by downgrading the production values. The problem of quality and quantity losses to sweet potato by this pest is one of the major problems nowadays. It caused this problem alone or interaction with other plant-parasitic pathogens or through synergistic of fungi, bacteria, viruses, and others. Therefore, this review paper is focused on the sweet potato M. incognita biology, taxonomy, geographical distribution, and management measures.

2021 ◽  
Author(s):  
Jonathan D. Eisenback

Abstract Introduction: The root knot nematode species, M. incognita, is the most widespread and probably the most serious plant parasitic nematode pest of tropical and subtropical regions throughout the world (Sasser, 1979). It occurs as a pest on a very wide range of crops. Most estimates of yield loss come from the use of nematicides and it should be noted that these can possibly cause other beneficial growth effects.


2021 ◽  
Author(s):  
Jonathan D. Eisenback

Abstract The root knot nematode species, M. incognita, is the most widespread and probably the most serious plant parasitic nematode pest of tropical and subtropical regions throughout the world (Sasser, 1979). It occurs as a pest on a very wide range of crops. Most estimates of yield loss come from the use of nematicides and it should be noted that these can possibly cause other beneficial growth effects.


Author(s):  
Anil Baniya ◽  
Soumi Joseph ◽  
Larry Duncan ◽  
William Crow ◽  
Tesfamariam Mengistu

AbstractSex determination is a key developmental event in all organisms. The pathway that regulates sexual fate has been well characterized at the molecular level in the model free-living nematode Caenorhabditis elegans. This study aims to gain a preliminary understanding of sex-determining pathways in a plant-parasitic nematode Meloidogyne incognita, and the extent to which the roles of the sex determination genes are conserved in a hermaphrodite species, C. elegans, and plant-parasitic nematode species, M. incognita. In this study, we targeted two sex-determining orthologues, sdc-1 and tra-1 from M. incognita using RNA interference (RNAi). RNAi was performed by soaking second-stage juveniles of M. incognita in a solution containing dsRNA of either Mi-tra-1or Mi-sdc-1 or both. To determine the effect of RNAi of the target genes, the juveniles treated with the dsRNA were inoculated onto a susceptible cultivar of cowpea grown in a nutrient pouch at 28 °C for 5 weeks. The development of the nematodes was analyzed at different time points during the growth period and compared to untreated controls. Our results showed that neither Mi-sdc-1 nor Mi-tra-1 have a significant role in regulating sexual fate in M. incognita. However, the silencing of Mi-sdc-1 significantly delayed maturity to adult females but did not affect egg production in mature females. In contrast, the downregulation of Mi-tra-1 transcript resulted in a significant reduction in egg production in both single and combinatorial RNAi-treated nematodes. Our results indicate that M. incognita may have adopted a divergent function for Mi-sdc-1 and Mi-tra-1distinct from Caenorhabditis spp. However, Mi-tra-1 might have an essential role in female fecundity in M. incognita and is a promising dsRNA target for root-knot nematode (RKN) management using host-delivered RNAi.


2019 ◽  
Vol 18 (4) ◽  
pp. 62-69
Author(s):  
Phong V. Nguyen

Effectors have been identified to play a very important role in the parasitism of plant-parasitic nematode. To cope with this type of pathogen, many approaches of silencing genes encoding for effectors have been studied and promise to be an effective tool to create plant varieties resistant to plant-parasitic nematodes. In this study, the Minc16281 gene encoding a pioneer effector with unknown function was determined and cloned from a Meloidogyne incognita population isolated from soybean field (ID: MH315945.1). The nucleotide sequence of this gene showed 97% identity to its homolog in GenBank (ID: JK287445.1) used as the control strain in our research. To generate host-induced gene silencing constructs which can potentially silence the expression of Minc16281 gene, two artificial microRNAs were synthesized based on the miR319a structure of Arabidopsis thaliana and inserted into an expression vector in soybean. These microRNAs can be introduced into soybean to investigate the function of Minc16281 on parasitism of root-knot nematode.


2019 ◽  
Vol 18 (3) ◽  
pp. 45-52 ◽  
Author(s):  
Tariq Mukhtar ◽  
Muhammad Zameer Kayani

Root-knot nematodes have become a grave menace to the lucrative production of cucumber throughout the world. These nematodes are mainly controlled by applying nematicides, but their use is often associated with hazards. Alternatively, the use of nematode resistant cultivars is considered to be innocuous and economically feasible. For their fitness as nematode-suppressive crops, the reduction in growth and yield parameters of these cultivars must be assessed. As there is little documented data about the effects of Meloidogyne incognita on the damage of cucumber, therefore, in the present study, the effects of M. incognita were evaluated on growth and yield parameters of fifteen cucumber cultivars. M. incognita significantly negatively affected the growth and yield parameters of all the cucumber cultivars. Shoot and root lengths and shoot weights of all the cultivars were significantly reduced as a result of nematode infection. Maximum reductions in these parameters were recorded in highly susceptible cultivars followed by susceptible ones, while the reductions were minimal in resistant followed by moderately resistant cultivars. On the contrary, the infection by M. incognita resulted in an increase in root weights of all the cultivars. The increase was found to be the maximum in highly susceptible cultivars followed by susceptible and moderately susceptible cultivars. Likewise, the minimum increase was observed in the resistant cultivars followed by moderately resistant cultivars. Similarly, significant variations in yield parameters among fifteen cucumber cultivars were also recorded as a result of M. incognita infection. In the case of highly susceptible cultivars, the reductions in yield parameters were maximum, whereas the reductions in resistant and moderately resistant cultivars were found to be minimum. As cultivars Long Green, Marketmore, Pioneer-II, Dynasty and Summer Green experienced no significant damage compared to susceptible cucumber cultivars and therefore, they are approved for cultivation in nematode infested soils.


2021 ◽  
Author(s):  
Rahim Hassanaly-Goulamhoussen ◽  
Ronaldo De Carvalho Augusto ◽  
Nathalie Marteu-Garello ◽  
Arthur Péré ◽  
Bruno Favery ◽  
...  

In model organisms, epigenome dynamics underlies a plethora of biological processes. The role of epigenetic modifications in development and parasitism in nematode pests remains unknown. The root-knot nematode Meloidogyne incognita adapts rapidly to unfavorable conditions, despite its asexual reproduction. However, the mechanisms underlying this remarkable plasticity and their potential impact on gene expression remain unknown. This study provides the first insight into contribution of epigenetic mechanisms to this plasticity, by studying histone modifications in M. incognita. The distribution of five histone modifications revealed the existence of strong epigenetic signatures, similar to those found in the model nematode Caenorhabditis elegans. We investigated their impact on chromatin structure and their distribution relative to transposable elements (TE) loci. We assessed the influence of the chromatin landscape on gene expression at two developmental stages: eggs, and pre-parasitic juveniles. H3K4me3 histone modification was strongly correlated with high levels of expression for protein-coding genes implicated in stage-specific processes during M. incognita development. We provided new insights in the dynamic regulation of parasitism genes kept under histone modifications silencing. In this pioneering study, we establish a comprehensive framework for the importance of epigenetic mechanisms in the regulation of the genome expression and its stability in plant-parasitic nematodes.


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