Diversity and plant growth-promoting potential of actinomycetes associated with the rhizosphere of Arnebia euchroma from Himachal Pradesh (India)

Abstract

Aim: The present study aimed to explicate the diversity and plant growth promoting (PGP) potential of actinomycetes present in the rhizosphere of an endangered medicinal plant, Arnebia euchroma. Methodology: Rhizospheric soil samples of A. euchroma collected from trans-Himalayan region of Himachal Pradesh were processed for elucidating actinomycetes diversity and load by employing Standard Plate Count Technique. All recovered isolates were screened for their PGP potential using standard protocols. The potential strains were identified through 16SrRNA ribotyping and were deposited in the National Culture Collection Centre, NCMR, Pune, (India). Results: The rhizosphere of A. euchroma harboured a great deal of actinomycetes diversity (33 diverse morphotypes). Starch casein agar was best for isolating the actinomycetes. The same actinomycete isolate showed variations in their morphological features including pigments production on different isolation media. They exhibited multifarious plant growth-promoting activities like P- solubilization, phytase activity, N- fixation, siderophore production etc. The potential isolates were identified as Streptomyces silaceus CA7 (MK836019) and Streptomyces rectiviolaceus NA8 (MK836018). Interpretation: The actinomycetes evinced a considerable plant growth promoting potential that might be helpful in the adaptation and perpetuation of A. euchroma under prevailing harsh environmental conditions of Himachal Pradesh.