Rhizobium oryzicola sp nov., potential plant-growth-promoting endophytic bacteria isolated from rice roots

Bacterial strains ZYY136(T) and ZYY9 were isolated from surface-sterilized rice roots from a long-term experiment of rice rice Astragalus sinicus rotation. The 16S rRNA gene sequences of strains ZYY136(T) and ZYY9 showed the highest similarity, of 97.0 %, to Rhizobium tarimense PL-41(T). Sequence analysis of the housekeeping genes recA, thrC and atpD clearly differentiated the isolates from currently described species of the genus Rhizobium. The DNA DNA relatedness value between ZYY136(T) and ZYY9 was 82.3 %, and ZYY136(T) showed 34.0 % DNA DNA relatedness with the most closely related type strain, R. tarimense PL-41T. The DNA G+C content of strain ZYY136T was 58.1 mol%. The major cellular fatty acids were summed feature 8 (C-18 :1 omega 7c and/or C-18:1 omega 6c), C-16 :0 and C-16 :0 3-OH. Strains ZYY136(T) and ZYY9 could be differentiated from the previously defined species of the genus Rhizobium by several phenotypic characteristics. Therefore, we conclude that strains ZYY136(T) and ZYY9 represent a novel species of the genus Rhizobium, for which the name Rhizobium oryzicola sp. nov. is proposed (type strain ZYY136(T)=ACCC 05753(T)=KCTC 32088(T)).