A group from Department of Life Science, Dongguk University-Seoul, Goyang 10326, Korea has reported that Arthrobacter sp. GN70 inoculated into the rice plants showed a significantly positive effect on shoot length, root length, fresh plant weight, and dry plant weight.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9228311/
In this study, 504 strains were isolated through culture-dependent methods and tested for the PGPB traits for each strain. Based on its high IAA value, PGPB traits, and antagonism towards pathogenic microorganisms, Arthrobacter sp. GN70 was selected for inoculation in rice plants, under lab and greenhouse conditions. Strain GN70 successfully attached to the roots, produced fibril matrix, and enhanced the rice plant growth, lateral roots, and weight. The strain also showed antagonistic effects towards plant and human pathogens.
The Arthrobacter species, designated as GN70, produced the highest amount of IAA (50.3 µg/mL) among other PGPB including Sphingomonas, Ideonella, Burkholderia, and Agromyces.
The colonization of the rice root surface by Arthrobacter sp. GN70 was significant as shown below.
(a) Arthrobactor sp. colonized, (b) control
Arthrobacter sp. GN70 produces EPS, which may hold water or increase the water-holding capacity in the soil to assist the bacteria and the plant roots under water-deficit stress. The ability to form biofilms both enhances bacterial survival and also enhances plant growth through the various PGPR-associated mechanisms. The GN70 can be utilized as plant growth promoters, suppressors of plant pathogens, and alleviators of water-deficit stress. Actually, the antifungal activity of GN70 showed an inhibitory region in the F. proliferatum KACC 44025, which mainly affects the rice plant with rice spikelet rot disease.
Based on the t-test, the rice seeds inoculated with Arthrobacter sp. GN70 increased significantly in shoot length, root length, fresh plant weight, and dry plant weight by 143.5%, 83.5%, 112.1%, and 256.7%, respectively.