Arthrobacter pokkalii sp nov, a Novel Plant Associated Actinobacterium with Plant Beneficial Properties, Isolated from Saline Tolerant Pokkali Rice, Kerala, India

Abstract

A novel yellow colony-forming bacterium, strain P3B162T was isolated from the pokkali rice rhizosphere from Kerala, India, as part of a project study aimed at isolating plant growth beneficial rhizobacteria from saline tolerant pokkali rice and functionally evaluate their abilities to promote plant growth under saline conditions. The novel strain P3B162T possesses plant growth beneficial traits such as positive growth on 1-aminocyclopropane-1-carboxylic acid (ACC), production of indole acetic acid (IAA) and siderophore. In addition, it also showed important phenotypic characters such as ability to form biofilm and utilization of various components of plant root exudates (sugars, amino acids and organic acids), clearly indicating its lifestyle as a plant rhizosphere associated bacterium. Taxonomically, the novel strain P3B162T was affiliated to the genus Arthrobacter based on the collective results of phenotypic, genotypic and chemotaxonomic analyses. Moreover, molecular analysis using 16S rRNA gene showed Arthrobacter globiformis NBRC 12137T, Arthrobacter pascens DSM 20545T and Arthrobacter liuii DSXY973T as the closely related phylogenetic neighbours, showing more than 98% 16S rRNA similarity values, whereas the recA gene analysis displayed Arthrobacter liuii JCM 19864T as the nearest neighbour with 94.7% sequence similarity and only 91.7% to Arthrobacter globiformis LMG 3813T and 88.7% to Arthrobacter pascens LMG 16255T. However, the DNA-DNA hybridization values between strain P3B162T, Arthrobacter globiformis LMG 3813T, Arthrobacter pascens LMG 16255T and Arthrobacter liuii JCM 19864T was below 50%. In addition, the novel strain P3B162T can be distinguished from its closely related type strains by several phenotypic characters such as colony pigment, tolerance to NaCl, motility, reduction of nitrate, hydrolysis of DNA, acid from sucrose, cell wall sugars and cell wall peptidoglycan structure. In conclusion, the combined results of this study support the classification of strain P3B162T as a novel Arthrobacter species and we propose Arthrobacter pokkalii sp.nov.as its name. The type strain is P3B162T (= KCTC 29498T = MTCC 12358T).

An endophyte from salt-adapted Pokkali rice confers salt-tolerance to a salt-sensitive rice variety and targets a unique pattern of genes in its new host

“…Li et al 21 showed that in contrast to the widely grown, but salt-sensitive rice variety IR-29, genes responsible for cell wall integrity, detoxifying ROS and photosynthesis are highly expressed in the salt-tolerant Pokkali rice. Novel rhizosphere-associated bacteria [22][23][24] such as Sphingomonas pokkali 25 have been shown to be associated with adaptation of the Pokkali varieties to the brackish rhizospheric environment. We show that the Pokkali races harbor Figure 3.…”

Bacterial population dynamics after foliar fertilization of almond leaves

“…This phenomenon may partially explain the increase in the percentage of these sequences. The decrease in the percentage of sequences associated with the phylum Actinobacteria in the foliar-treated library was associated with a significant decrease in percentage of sequences associated with the family Micrococcaceae genera Arthrobacter and Kocuria, which have been previously reported as plant-associated bacteria (Kovacs et al 1999;Krishnan et al 2016).…”

Characterization of endophytic bacteria with plant growth promotion and biological control potential isolated from walnut trees

“…The genus Arthrobacter represents strains associated with different plants and is often described as bacteria with their ability to promote plant growth (Celador-Lera et al, 2016). Strains were found to be beneficial to the plants via production of IAA and siderophore (Krishnan et al, 2016). Strain KS54 showed high similarity to A. oryzae.…”