scholarly journals Histopathology of the nematodes Radopholus similis, Pratylenchus coffeae, Rotylenchulus reniformis and Meloidogyne incognita in plantain (Musa acuminata x M. balbisiana, AAB).

1969 ◽  
Vol 90 (1-2) ◽  
pp. 83-97
Author(s):  
Domingo Oramas-Nival ◽  
Jessé Román

Radopholus similis produced sunken lesions that modified the normal cylindrical anatomy of the plantain root under severe necrotic conditions. The lesions caused by R. similis were similar to those caused by Pratylenchs coffeae, except that the latter did not alter the turgid condition of the root. At cellular level, R. similis induced hypertrophy of the nucleus and nucleolus of the cortical cells; however, P. coffeae did not produce a similar reaction. Rotylenchulus reniformis concentrated the parasitic activity on the feeder roots, thus causing necrosis at the feeding site. The reniform nematode induced a syncytia made up mainly of fourteen to twenty longitudinal and circumferential cells of the pericycle.The cells, the nucleus and the nucleolus of the syncytia were hypertrophied. Two nucleoli were observed in some of the syncytial cells. The cytoplasm of the syncytia was granular, dense and had spheric inclusions. A solid and mustache-like structure that we called feeding filter was observed between the feeding cell and the pericycle. The root-knot nematode, Meloidogyne incognita, caused profuse root galls and cortical cracks in the roots and exposition of the internal tissue, mainly at the distal portion of the main roots. Meloidogyne incognita penetrated the endodermis and the pericycle and induced hypertrophy on five to seven of the vascular parenchymal cells with multiple hypertrophied nuclei.

2020 ◽  
Vol 3 (2) ◽  
pp. 21-31
Author(s):  
Sudeep Subedi ◽  
Bihani Thapa ◽  
Jiban Shrestha

Root-knot nematode (RKN) Meloidogyne incognita stands out among the most harmful polyphagous endoparasite causing serious harm to plants, and distributed all over the globe. RKN causes reduced growth, quality and yield along with reduced resistance of the host against biotic and abiotic stresses. Infective second stage juvenile enters host roots with the help of the stylet and becomes sedentary getting into the vascular cylinder. Dramatic changes occur in host cells, making a specialized feeding site, induced by the secretion of effector protein by RKN. M. incognita can be controlled by nematicides, biocontrol agents, botanicals essential oils and growing resistant cultivars. Nematicides are no longer allowed to use in many parts of the world because of environmental hazards and toxicity to humans and other organisms. Researchers are concentrating on searching suitable alternatives to nematicides for effective management of M. incognita. This review mainly tries to explain the biology of M. incognita and different management options recommended in recent years. However, an effective and economical management of M. incognita remains an immense challenge.


1999 ◽  
Vol 89 (8) ◽  
pp. 613-617 ◽  
Author(s):  
N. R. Walker ◽  
T. L. Kirkpatrick ◽  
C. S. Rothrock

Controlled environments were used to study the relationship between the root-knot nematode (Meloidogyne incognita) and Thielaviopsis basicola on cotton. Temperature treatments were continuous 20, 24, and 28°C or two cyclic linear regimes with ranges of 14 to 32 or 18 to 28°C over 24 h. Cotton seeds were planted in fumigated soil infested with T. basicola, M. incognita, or both. After 42 days, pathogen effects on plant growth and pathogen development were evaluated. Histology was conducted on roots collected 14, 28, and 42 days after planting in the continuous 24°C treatment. Reductions in plant height-to-node ratio and total fresh weight were observed for soils infested with both pathogens compared with the control or with soils infested with either pathogen, except for M. incognita-infested soil at 28°C. T. basicola reduced root galling and reproduction of the nematode at all temperatures. Vascular discoloration caused by T. basicola was greater in the presence of M. incognita compared with that by T. basicola alone. At 2 and 4 weeks, histological studies showed that plants grown in all T. basicola-infested soils contained chlamydospore chains on the root surface and in cortical cells. The fungus was not observed inside the vascular cylinder. Roots from 4-week-old plants from soils infested with T. basicola and M. incognita showed fungal sporulation in vascular tissue and localized necrosis of vascular tissue adjacent to the nematodes. At 6 weeks, plants grown in soil infested with T. basicola alone exhibited no remaining cortical tissue and no evidence of vascular colonization by the fungus. Six-week-old plants grown in T. basicola + M. incognita-infested soils exhibited extensive vascular necrosis and sporulation within vascular tissue. These studies suggest that coinfection expands the temperature ranges at which the pathogens are able to cause plant damage. Further, M. incognita greatly increases the access of T. basicola to vascular tissue.


1969 ◽  
Vol 66 (1) ◽  
pp. 52-59
Author(s):  
D. Oramas ◽  
J. Román

A survey was conducted through the five argricultural regions of Puerto Rico to determine distribution and population density of the nematode species associated with plantain. Fourteen genera, represented by 19 species of phytoparasitic nematodes were found in association with the crop: Ditylenchus, Helicotylenchus, Hoplolaimus, longidorus, Meloidogyne, Paratylenchus, Pratylenchus, Pseudhalenchus, Quinisulcius, Radopholus, Rotylenchulus, Tylenchorhynchus, Tylenchus, and Xiphinema. Meloidogyne incognita, Helicotylenchus spp., Radopholus similis, and Rotylenchulus reniformis were the most widely distributed nematode species throughout the Island. On the other hand, M. incognita, P. coffeae, R. similis, Helicotylenchus spp. , and R. reniformis had higher population densities.


2020 ◽  
Vol 7 (1) ◽  
pp. 044-048
Author(s):  
Vinod Kumar ◽  
◽  
Prakash Banakar ◽  
Anil Kumar ◽  
Priyanka Duggal ◽  
...  

An extensive survey was conducted to assess the frequency and abundance of plant-parasitic nematodes associated with cotton (Gossypium hirsutum L.) in Haryana (Nuh and Palwal districts) during 2018-20. Based on incidence, population density and associated damage on affected crops, root-knot nematode (Meloidogyne incognita) was considered to be the most important parasite of the crops under local condition. During 2018-19, a total of 11 soil and root samples of cotton were collected from Nuh and Palwal districts. Out of these, eight were found infected with M. incognita with 72.0% frequency of occurrence. The results revealed that out of 7 samples (Nuh), five were found infested with M. incognita with 71.4% frequency of occurrence. In Palwal district, this nematode had 75.0% frequency of occurrence with density range of 60-300 j2 200-1 cc soil. During 2019-20, a total of 27 soil and root samples of cotton were collected from Nuh and Palwal districts. Out of these, 14 were found infected with M. incognita with 51.8% frequency of occurrence. The results revealed that out of 21 samples (Nuh), 12 were found infested with M. incognita with 57.1% frequency of occurrence and density range of 95-690 j2 200-1 cc soil. In Palwal district, this nematode had 33.3% frequency of occurrence (2 out of 6 samples) with density range of 135-435 j2 200-1 cc soil. Other plant parasitic nematodes which were found associated with the cotton belonged to Rotylenchulus reniformis, Hoplolaimus sp., Helicotylenchus sp. and Tylenchorhynchus sp.


2019 ◽  
Vol 20 (21) ◽  
pp. 5465 ◽  
Author(s):  
Christianna Meidani ◽  
Nikoletta G. Ntalli ◽  
Eleni Giannoutsou ◽  
Ioannis-Dimosthenis S. Adamakis

Meloidogyne incognita is a root knot nematode (RKN) species which is among the most notoriously unmanageable crop pests with a wide host range. It inhabits plants and induces unique feeding site structures within host roots, known as giant cells (GCs). The cell walls of the GCs undergo the process of both thickening and loosening to allow expansion and finally support nutrient uptake by the nematode. In this study, a comparative in situ analysis of cell wall polysaccharides in the GCs of wild-type Col-0 and the microtubule-defective fra2 katanin mutant, both infected with M. incognita has been carried out. The fra2 mutant had an increased infection rate. Moreover, fra2 roots exhibited a differential pectin and hemicellulose distribution when compared to Col-0 probably mirroring the fra2 root developmental defects. Features of fra2 GC walls include the presence of high-esterified pectic homogalacturonan and pectic arabinan, possibly to compensate for the reduced levels of callose, which was omnipresent in GCs of Col-0. Katanin severing of microtubules seems important in plant defense against M. incognita, with the nematode, however, to be nonchalant about this “katanin deficiency” and eventually induce the necessary GC cell wall modifications to establish a feeding site.


2012 ◽  
Vol 52 (3) ◽  
pp. 333-336 ◽  
Author(s):  
Hamida Osman ◽  
Mahmoud Youssef ◽  
Abd-El-Moneim El-Gindi ◽  
Hoda Ameen ◽  
Nagwa Abd-Elbary ◽  
...  

Effect of Reniform Nematode,Rotylenchulus Reniformisas Biotic Inducer of Resistance Against Root-Knot Nematode,Meloidogyne Incognitain PotatoA greenhouse experiment was conducted to evaluate the preinoculation of reniform nematode,Rotylenchulus reniformisfor inducing resistance againstMeloidogyne incognitain potato plants. Potato plants were inoculated with reniform nematode three days before the same plants received a root knot nematode inoculation. There was a reduction in the population parameters of the root knot nematode compared to plants given only a single inoculation. The studied potato plants which had two inoculations, also had enhanced growth parameters. The activity of the enzymes; peroxidase, polyphenol oxidase, and chitinase increased in the inoculated plants compared to the non-inoculated control.


Fruits ◽  
2009 ◽  
Vol 64 (5) ◽  
pp. 295-303 ◽  
Author(s):  
Hang Ye ◽  
Wen-jun Wang ◽  
Guo-jie Liu ◽  
Li-xin Zhu ◽  
Ke-gong Jia

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 948-956 ◽  
Author(s):  
Alois A. Bell ◽  
Robert C. Kemerait ◽  
Carlos S. Ortiz ◽  
Sandria Prom ◽  
Jose Quintana ◽  
...  

Locally severe outbreaks of Fusarium wilt of cotton (Gossypium spp.) in South Georgia raised concerns about the genotypes of the causal pathogen, Fusarium oxysporum f. sp. vasinfectum. Vegetative complementation tests and DNA sequence analysis were used to determine genetic diversity among 492 F. oxysporum f. sp. vasinfectum isolates obtained from 107 wilted plants collected from seven fields in five counties. Eight vegetative complementation groups (VCG) were found, with VCG 01117B and VCG 01121 occurring in 66% of the infected plants. The newly recognized VCG 01121 was the major VCG in Berrien County, the center of the outbreaks. All eight VCG resulted in significant increases in the percentages of wilted leaves (27 to 53%) and significant reductions in leaf weight (40 to 67%) and shoot weight (33 to 60%) after being stem punctured into Gossypium hirsutum ‘Rowden’. They caused little or no significant reductions in shoot weight and height or increases in foliar symptoms and vascular browning in a soil-infestation assay. Soil infestation with Meloidogyne incognita race 3 (root-knot nematode) alone also failed to cause significant disease. When coinoculated with M. incognita race 3, all VCG caused moderate to severe wilt. Therefore, the VCG identified in this study belong to the vascular-competent pathotype, and should pose similar threats to cotton cultivars in the presence of the root-knot nematode. Use of nematode-resistant cultivars, therefore, is probably the best approach to control the disease in Georgia.


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