AUTHOR=Anwar Sumaira , Ali Basharat , Sajid Imran 

TITLE=Screening of Rhizospheric Actinomycetes for Various In-vitro and In-vivo Plant Growth Promoting (PGP) Traits and for Agroactive Compounds

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01334

DOI=10.3389/fmicb.2016.01334

ISSN=1664-302X

ABSTRACT=<p>In this study 98 rhizospheric actinomycetes were isolated from different wheat and tomato fields, Punjab, Pakistan. The isolates were characterized morphologically, biochemically, and genetically and were subjected to a comprehensive <italic>in vitro</italic> screening for various plant growth promoting (PGP) traits. About 30% of the isolates screened were found to be the promising PGP rhizobacteria (PGPRs), which exhibited maximum genetic similarity (up to 98–99%) with different species of the genus <italic>Streptomyces</italic> by using16S rRNA gene sequencing. The most active indole acetic acid (IAA) producer <italic>Streptomyces nobilis</italic> WA-3, <italic>Streptomyces Kunmingenesis</italic> WC-3, and <italic>Streptomyces enissocaesilis</italic> TA-3 produce 79.5, 79.23, and 69.26 μg/ml IAA respectively at 500 μg/ml L-tryptophan. The highest concentration of soluble phosphate was produced by <italic>Streptomyces</italic> sp. WA-1 (72.13 mg/100 ml) and <italic>S. djakartensis</italic> TB-4 (70.36 mg/100 ml). All rhizobacterial isolates were positive for siderophore, ammonia, and hydrogen cyanide production. Strain <italic>S. mutabilis</italic> WD-3 showed highest concentration of ACC-deaminase (1.9 mmol /l). For <italic>in-vivo</italic> screening, seed germination, and plant growth experiment were conducted by inoculating wheat (<italic>Triticum aestivum</italic>) seeds with the six selected isolates. Significant increases in shoot length was observed with <italic>S. nobilis</italic> WA-3 (65%), increased root length was recorded in case of <italic>S. nobilis</italic> WA-3 (81%) as compared to water treated control plants. Maximum increases in plant fresh weight were recorded with <italic>S. nobilis</italic> WA-3 (84%), increased plant dry weight was recorded in case of <italic>S. nobilis</italic> WA-3 (85%) as compared to water treated control plants. In case of number of leaves, significant increase was recorded with <italic>S. nobilis</italic> WA-3 (27%) and significant increase in case of number of roots were recorded in case of strain <italic>S. nobilis</italic> WA-3 (30%) as compared to control plants. Over all the study revealed that these rhizospheric PGP <italic>Streptomyces</italic> are good candidates to be developed as bioferlizers for growth promotion and yield enhancement in wheat crop and can be exploited for the commercial production of different agro-active compounds.</p>