The nematicidal potentiality of some algal extracts and their role in enhancement the tomato defense genes against root knot - nematodes

Abstract

The nematicidal effect of three marine algal, Ulva fasciata Delile (UF) (green algae), Corallina mediterranea, Corallina officinalis (red algae), extracts on egg hatching and second-stage juveniles (J 2 ) mortality of root-knot nematode (Meloidogyne incognita) in vitro compared to the nematicide activity of Oxamyl 24% SL (5 ml/l) was investigated. Results revealed that all treatments at the applied concentrations suppressed the egg hatching in 3 days. In details, the algal strain Ulva fasciata Delile extract showed the highest activity in decreasing the eggs hatchability after 3 days with 87%. Consequently, all treatments significantly increased the mortality of J 2 larvae after 12, 24, and 48 h compared to the control treated with distilled water. Under greenhouse conditions, all treatments in inoculated soils cultivated with tomato plants had reduced numbers of galls, egg-masses/plant, and the number of J 2 /250 g than the non-inoculated soil. The algal extract and the Oxamyl 24% SL (5 ml/l) increased the length and fresh weight of plant shoots and roots than the untreated. However, there were no differences in shoots and roots fresh weights and their lengths in the plant treated with Oxamyl 24% SL (5 ml/l) or the extracts of U. fasciata and Corallina officinalis. These results were closely similar to control. Both of peroxidase and polyphenol enzymes activity for the control plants remained relatively stable, while the activity of the two enzymes in the plant inoculated with the nematode decreased during 2 to 18 day post inoculation (dpi). These activities increased in inoculated plants treated with C. officinalis, C. mediterranea, and U. fasciata extracts and the other plants treated with Oxamyl 24% SL (5 ml/l). The maximum activity of the three enzymes was recorded at 5 dpi after treatment with U. fasciata.

Utilization of Cladophora glomerata extract nanoparticles as eco-nematicide and enhancing the defense responses of tomato plants infected by Meloidogyne javanica

“…PAL is the main enzyme of phenylpropanoid metabolism and is closely linked to the production of phenolic, coumaric, and caffeic compounds such as toxic chemical substances during nematode infection 38,[57][58][59] . Our study proposed that the induction of PAL and PPO activities was significantly higher in infected tomato plants after treated with algal extract and GSNPs, respectively, than in the non-inoculated and untreated ones (see Fig.…”

“…Another ten were inoculated with nematode and treated with Rugby 60% at 1 mL/pot to serve as the second control. The other 20 pots were divided into two groups of ten pots each 38 , with slightly modifications. The first group was inoculated with nematodes (4000 J2S) and treated with C. glomerata aqueous extract 50 mL/pot (5 mg/50 mL).…”

“…One gram of root was homogenized in a 5 ml extraction buffer (50 mM phosphate buffer, pH 7.0, 1 mM EDTA, and 2% Polyvinylpyrrolidone, PVPP) for POX and PPO extracted and (25 mM Tris-HCl buffer) (PH 8.8) for PAL extracted in an ice-cold pastel mortar. The homogenate was centrifuged at 12,000× g for 300 min at 4 °C (Ultracentrifuge CFC Free, Gallenkamp, Germany) and the supernatant was directly used for enzyme activity assays 38 . PAL , POX, and PPO activity assays were performed as described by Hussey et al 29 .…”

Bacterial Community Structure Dynamics in Meloidogyne incognita -Infected Roots and Its Role in Worm-Microbiome Interactions

“…The interaction between the virulence of M. incognita and the microbial diversity in the various niches M. incognita occupy has been studied in the context of biological control, revealing complex relationships, which efficacy diminishes with the transfer from lab to field ( 20 ). In this field of research, common themes include the isolation of Meloidogyne pathogens from the cuticles of J2s ( 21 – 23 ) and the identification of soil microbes and bacterial volatile compounds with antagonistic effects ( 24 , 25 ) from key taxa, including Rhizobia ( 26 ), Trichoderma and Pseudomonas ( 27 , 28 ), Pasteuria ( 29 ), Pochonia ( 30 , 31 ), and some mycorrhiza ( 31 – 33 ).…”

The bacterial community structure dynamics inMeloidogyne incognitainfected roots and its role in worm-microbiome interactions

“…The interaction of M. incognita virulence and microbial taxa in the various niches they occupy, have been studied in the context of biological control, revealing complex relationships, which efficacy diminishes with the transfer from lab to field [20] . Common themes in this line of research include the isolation of Meloidogyne pathogens from the cuticle of second stage juveniles (J2) [21][22][23] , or the identification of soil microbes and bacterial volatile compounds with antagonistic effects [24,25] , key taxa including Rhizobia [26] , Trichoderma and Pseudomonas [27,28] , Pasteuria [29] , Pochonia [30,31] and some mycorrhiza [31][32][33] .…”