Exploration of Potential Bacterial Endophytes against Root Knot Nematode, Meloidogyne incognita in Banana

Devrajan K,Raveendran M,Vetrivelkalai P,Balachandar D,Ganeshan K,Nibha G,Bhagawati B

doi:10.29321/maj.10.000540

Abstract

A field survey was conducted in 12 districts of Assam viz., Jorhat, Golaghat, Nagaon, Marigaon, Goalpara, Dibrugarh, Tinsukia, Lakhimpur, Dhemaji, Sivsagar, Kamrup and Barpeta. A total of 92 root samples were collected and 37 bacterial isolates were isolated from commercial banana cultivars. The culture filtrates extracted from 37 endophytic bacterial isolates, were screened against southern root-knot nematode, Meloidogyne incognita in vitro and under pot culture studies. The five bacterial isolates viz., EB4, EB8, BC1, BC11 and BC12 showed 100% inhibition of egg hatching and juvenile mortality of M. incognita with an exposure period of 48 and 72h. On seed bacterization, with these five promising isolates, two isolates viz.EB4, BC1 significantly enhanced germination percentage (33.33, 25.31%) and vigour index (75.5, 64.39%) of paddy, receptively. The potential bacterial isolates viz., BC1 and EB4 were identified as Lysinibacillus sp. and Pseudomonas sp., respectively , based on the morphological phenotypic and biochemical characterization. The pot culture experiment revealed that the bacterial endophytes viz., Lysinibacillus sp. (BC1) Pseudomonas sp. (EB4) significantly reduced the soil (61.64, 56.71%) and root nematode population (77.29, 68.87%), number of adult females (73.97, 69.89%), egg masses (85.63, 80.11%) and root-knot index (1.33, 1.67) of M. incognita compared to untreated control. The bacterial endophytes viz., Pseudomonas sp. (EB4), Lysinibacillus sp. (BC1) were also significantly increased the growth parameters viz., shoot length (43.33, 39.18%), and root length (78.24, 59.26%) and pesudostem girth (58.38, 52.13%).

Highlights

Root-knot nematode, Meloidogyne spp. are obligate, sedentary endoparasites of more than 3000 host plants throughout the world (Sasser, 1979)
A total of 37 endophytic bacterial isolates were obtained from different banana cultivars viz., Malbhog, Seni Champa and Jahaji
Isolation of endophytic bacterial strains from various monocots and woody plants has reported by several authors (Ragavi et al, 2019; Kaushal et al, 2020 and Gomez-Lama Cabanas et al (2021)

Summary

Introduction

Root-knot nematode, Meloidogyne spp. are obligate, sedentary endoparasites of more than 3000 host plants throughout the world (Sasser, 1979). The southern root-knot nematode, M. incognita is one of the major constraints in the production of banana and caused the 15% yield loss in India (Kumar et al, 2020). Plants have complex micro-ecosystems in which different niches are filled by a wide variety of beneficial microorganisms (Souza et al, 2013). Bacterial endophytes act as biocontrol agents for nematodes (Jie et al, 2009) and promote plant growth in various crops (Kausal et al, 2017). Most commercial biocontrol products on the market contain live microorganisms, such as Pasteuria penetrans, Purpureocillium lilacinum, and/or their metabolites, which target specific nematodes (Lamovsek et al, 2013)

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Conclusion