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

Abstract

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 in vitro 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 Streptomyces by using16S rRNA gene sequencing. The most active indole acetic acid (IAA) producer Streptomyces nobilis WA-3, Streptomyces Kunmingenesis WC-3, and Streptomyces enissocaesilis 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 Streptomyces sp. WA-1 (72.13 mg/100 ml) and S. djakartensis TB-4 (70.36 mg/100 ml). All rhizobacterial isolates were positive for siderophore, ammonia, and hydrogen cyanide production. Strain S. mutabilis WD-3 showed highest concentration of ACC-deaminase (1.9 mmol /l). For in-vivo screening, seed germination, and plant growth experiment were conducted by inoculating wheat (Triticum aestivum) seeds with the six selected isolates. Significant increases in shoot length was observed with S. nobilis WA-3 (65%), increased root length was recorded in case of S. nobilis WA-3 (81%) as compared to water treated control plants. Maximum increases in plant fresh weight were recorded with S. nobilis WA-3 (84%), increased plant dry weight was recorded in case of S. nobilis WA-3 (85%) as compared to water treated control plants. In case of number of leaves, significant increase was recorded with S. nobilis WA-3 (27%) and significant increase in case of number of roots were recorded in case of strain S. nobilis WA-3 (30%) as compared to control plants. Over all the study revealed that these rhizospheric PGP Streptomyces 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.

Deciphering the Factors for Nodulation and Symbiosis of Mesorhizobium Associated with Cicer arietinum in Northwest India

“…It is established well that plant associated-bacteria lowers the ethylene levels of plants through the ACC deaminase activity and helps to grow under biotic and abiotic stresses [61]. In this study, all the strains were found positive for ACC deaminase, but it was lower than previous reports of ACC-D production by Pseudomonas fluorescens and Streptomyces djakartensis TB4 [61][62][63].…”

Plant growth promotion and chilli anthracnose disease suppression ability of rhizosphere soil actinobacteria

“…ACC can be converted into ammonia and a-ketobutyrate (Honma and Shimomura 1978) by the enzyme ACC deaminase that bring down plant ethylene levels. Streptomyces are reported to possess ACC deaminase activity (Wang et al 2000;Ali et al 2012) and can help to reduce pathogen related plant stress (Munees and Mulugeta 2014;Anwar et al 2016).…”

Streptomyces spp. from rhizosphere soil of maize with potential as plant growth promoter

“…Similarly, in the previous study by Kaur et al (2017) reported that 16 isolates of Actinomycetes isolated from the rhizosphere of Gladiolus were able to produce IAA with concentrations ranging from 8.1 to 79.9 ppm. Anwar et al (2016) also reported that 30 Actinomycetes isolated from the rhizosphere of wheat and tomatoes were able to produce IAA with concentrations ranging from 10-79.5 ppm. The results of this study indicated that the most Actinomycetes isolated from the rhizosphere of maize were able to produce IAA.…”