Effect of nitrogen supply form on the invasion of rice roots by the root-knot nematode, Meloidogyne graminicola

Nematology ◽  
2013 ◽  
Vol 15 (4) ◽  
pp. 483-492 ◽  
Author(s):  
Jagadeesh Patil ◽  
Anthony J. Miller ◽  
Hari S. Gaur

Rice is capable of taking up both nitrate (NO3−) and ammonical (NH4+) forms of nitrogen (N). It is largely grown under flooded cultivation when NH4+ is the main form of available soil N. The root knot nematode, Meloidogyne graminicola, can cause serious damage to rice crops and disturb N uptake and translocation. We have investigated if the N supply form can influence the susceptibility of rice to this important pest. Roots supplied with a 100-fold lower supply of calcium nitrate (0.1 mM Ca(NO3)2) showed a higher level of nematode infection as measured by the gall index. Plants supplied with 2.85 mM of Ca(NO3)2 were more infected compared with the same dose of ammonium nitrate (NH4NO3) or ammonium chloride (NH4Cl). 15NO3− influx studies showed significantly smaller uptake of nitrate in nematode-infected roots when compared with non-infected control plants. The electrophysiological studies showed that resting cell membrane potentials of nematode-infected plants were significantly smaller (less negative) than those of non-infected control rice. Furthermore, when the cellular responses to NO3− were compared, these also showed significantly smaller nitrate transport activity in nematode-infected roots (4.7 ± 1.2 mV) when compared with non-infected control plants (11.9 ± 3.4 mV). Taken together, the 15NO3− influx and electrophysiological measurements clearly showed that the root NO3− transport activity was severely decreased in nematode-infected roots. The results also show that regulation of NO3− concentration at critical periods of nematode infection of rice root can provide a non-nematicidal method of nematode management.

Nematology ◽  
2013 ◽  
Vol 15 (4) ◽  
pp. 469-482 ◽  
Author(s):  
Jagadeesh Patil ◽  
Stephen J. Powers ◽  
Keith G. Davies ◽  
Hari S. Gaur ◽  
Anthony J. Miller

Three experiments were conducted to compare the attraction and repulsion of second-stage juveniles (J2) of the root-knot nematode, Meloidogyne graminicola, to rice plants supplied with different forms of nitrogen. The rice plants were hydroponically grown in a full nutrient solution containing different concentrations (0.1 or 10.0 mM) of nitrate (NO3−) or forms of nitrogen supply (2.85 mM calcium nitrate (Ca(NO3)2), ammonium nitrate (NH4NO3) or ammonium chloride (NH4Cl)) for 2 weeks. Five rice plants were placed with their roots in one corner of a Perspex X or Y-chamber partly filled with agar and J2 were inoculated onto the chambers. The data show that J2 of M. graminicola were significantly attracted towards the roots of rice plants grown in hydroponics containing 0.1 mM NO3− and 2.85 mM Ca(NO3)2, but repelled by 10.0 mM NO3−, 2.85 mM NH4NO3 and NH4Cl. The results suggest that the application of ammonia-based nitrogen fertiliser to the rice nursery bed may interfere with nematode attraction and thus reduce invasion, and the application of chemical nitrification inhibitors to rice nursery beds may decrease nematode invasion.


2020 ◽  
Vol 71 (14) ◽  
pp. 4271-4284 ◽  
Author(s):  
Richard Raj Singh ◽  
Bruno Verstraeten ◽  
Shahid Siddique ◽  
Adelahu Mekonene Tegene ◽  
Raimund Tenhaken ◽  
...  

Abstract Ascorbic acid (AA) is the major antioxidant buffer produced in the shoot tissue of plants. Previous studies on root-knot nematode (RKN; Meloidogyne graminicola)-infected rice (Oryza sativa) plants showed differential expression of AA-recycling genes, although their functional role was unknown. Our results confirmed increased dehydroascorbate (DHA) levels in nematode-induced root galls, while AA mutants were significantly more susceptible to nematode infection. External applications of ascorbate oxidase (AO), DHA, or reduced AA, revealed systemic effects of ascorbate oxidation on rice defence versus RKN, associated with a primed accumulation of H2O2 upon nematode infection. To confirm and further investigate these systemic effects, a transcriptome analysis was done on roots of foliar AO-treated plants, revealing activation of the ethylene (ET) response and jasmonic acid (JA) biosynthesis pathways in roots, which was confirmed by hormone measurements. Activation of these pathways by methyl-JA, or ethephon treatment can complement the susceptibility phenotype of the rice Vitamin C (vtc1) mutant. Experiments on the jasmonate signalling (jar1) mutant or using chemical JA/ET inhibitors confirm that the effects of ascorbate oxidation are dependent on both the JA and ET pathways. Collectively, our data reveal a novel pathway in which ascorbate oxidation induces systemic defence against RKNs.


Author(s):  
Hui-Yu Chen ◽  
Shan-Hua Lin ◽  
Ling-Hsin Cheng ◽  
Jeng-Jong Wu ◽  
Yi-Chen Lin ◽  
...  

Abstract Compared with root development regulated by external nutrients, less is known about how internal nutrients are monitored to control plasticity of shoot development. In this study, we characterize an Arabidopsis thaliana transceptor, NRT1.13 (NPF4.4), of the NRT1/PTR/NPF family. Different from most NRT1 transporters, NRT1.13 does not have the conserved proline residue between transmembrane domains 10 and 11; an essential residue for nitrate transport activity in CHL1/NRT1.1/NPF6.3. As expected, when expressed in oocytes, NRT1.13 showed no nitrate transport activity. However, when Ser 487 at the corresponding position was converted back to proline, NRT1.13 S487P regained nitrate uptake activity, suggesting that wild-type NRT1.13 cannot transport nitrate but can bind it. Subcellular localization and β-glucuronidase reporter analyses indicated that NRT1.13 is a plasma membrane protein expressed at the parenchyma cells next to xylem in the petioles and the stem nodes. When plants were grown with a normal concentration of nitrate, nrt1.13 showed no severe growth phenotype. However, when grown under low-nitrate conditions, nrt1.13 showed delayed flowering, increased node number, retarded branch outgrowth, and reduced lateral nitrate allocation to nodes. Our results suggest that NRT1.13 is required for low-nitrate acclimation and that internal nitrate is monitored near the xylem by NRT1.13 to regulate shoot architecture and flowering time.


2019 ◽  
Vol 78 (2) ◽  
pp. 470-481 ◽  
Author(s):  
Dongmei Zhou ◽  
Hui Feng ◽  
Taruna Schuelke ◽  
Alejandro De Santiago ◽  
Qimeng Zhang ◽  
...  

1970 ◽  
Vol 9 ◽  
pp. 21-27 ◽  
Author(s):  
Nabin Kumar Dangal ◽  
D. Sharma Poudyal ◽  
S. M. Shrestha ◽  
C. Adhikari ◽  
J. M. Duxbury ◽  
...  

Pot experiment was conducted during July-September 2006 to evaluate some organic amendments such as sesame (Sesamum indicum) biomass, buckwheat (Fagopyrum esculentum) biomass, neem (Azadirachta indica) leaves, chinaberry (Melia azedarch) leaves and chicken manure @ 1, 2 and 3 t ha-1 each against the rice root-knot nematode (Meloidogyne graminicola Golden & Birchfield) in direct seeded rice. The treatments were replicated five times in a randomized complete block design. The number of second stage juveniles (J2) of M. graminicola was significantly low in chicken manure @ 3 t ha-1. The root knot severity index was significantly low in sesame @ 3 t ha-1, chinaberry @ 3, 2 or 1 t ha-1, neem @ 3 t ha-1 and chicken manure @ 2 or 3 t ha-1 amended soil but root lesion severity index was lower only in chicken manure @ 2 t ha-1 treated plots. The fresh shoot weight and length were significantly high in chicken manure amendment @ 2 or 3 t ha-1 at 45th day after seeding. However, the fresh root weight, length, number of leaves and number of J2 recovered from the roots were non-significant. Key words: biomass; juveniles; Meloidogyne graminicola; root-knot severity index; root lesion severity index DOI: 10.3126/njst.v9i0.3160 Nepal Journal of Science and Technology 9 (2008) 21-27


2021 ◽  
Author(s):  
Kazuki Sato ◽  
Taketo Uehara ◽  
Julia Holbein ◽  
Yuko Sasaki-Sekimoto ◽  
Pamela Gan ◽  
...  

ABSTRACTRoot-knot nematodes (RKNs) are among the most devastating pests in agriculture. Solanum torvum Sw. (turkey berry) has been used as a rootstock for eggplant (aubergine) cultivation because of its resistance to RKNs, including Meloidogyne incognita and M. arenaria. We previously found that a pathotype of M. arenaria, A2-J, is able to infect and propagate in S. torvum. In vitro infection assays showed that S. torvum induces the accumulation of brown pigments during avirulent pathotype A2-O infection, but not during virulent A2-J infection. This experimental system is advantageous because resistant and susceptible responses can be distinguished within a few days, and because a single plant genome can yield information about both resistant and susceptible responses. Comparative RNA-sequencing analysis of S. torvum inoculated with A2-J and A2-O at early stages of infection was used to parse the specific resistance and susceptible responses. Infection with A2-J did not induce statistically significant changes in gene expression within one day post-inoculation (DPI), but afterward, A2-J specifically induced the expression of chalcone synthase, spermidine synthase, and genes related to cell wall modification and transmembrane transport. Infection with A2-O rapidly induced the expression of genes encoding class III peroxidases, sesquiterpene synthases, and fatty acid desaturases at 1 DPI, followed by genes involved in defense, hormone signaling, and the biosynthesis of lignin at 3 DPI. Both isolates induced the expression of suberin biosynthetic genes, which may be triggered by wounding during nematode infection. Histochemical analysis revealed that A2-O, but not A2-J, induced lignin accumulation at the root tip, suggesting that physical reinforcement of cell walls with lignin is an important defense response against nematodes. The S. torvum-RKN system can provide a molecular basis for understanding plant-nematode interactions.


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