Isolation and characterization of new plant growth-promoting bacterial endophytes

Desert plants are able to survive under harsh environmental stresses inherent to arid and semiarid regions due to their association with bacterial endophytes. However, the identity, functions, and the factors that influence the association of bacterial endophytes with desert plants are poorly known. These bacterial endophytes can be used as an untapped resource to favor plant growth and development in agro-ecosystems of arid regions. The present study is therefore focused on the isolation and identification of bacterial endophytes from two native medicinal plants (Fagonia mollis Delile and Achillea fragrantissima (Forssk) Sch. Bip.) growing spontaneously in the arid region of the South Sinai (Egypt), and characterization of their plant growth promoting (PGP) traits. Thirteen putative bacterial endophytes were isolated from the leaves of both plant species and characterized for their plant growth promoting abilities using molecular and biochemical approaches, as well as greenhouse trials. Selected endophytic bacterial strains were applied to maize plants (Zea mays L. var. Single cross Pioneer 30K08) to further evaluate their PGP abilities under greenhouse conditions. Isolated bacterial strains have variable plant growth promoting activities. Among these activities, isolated bacterial endophytes have the efficacy of phosphate solubilizing with clear zones ranging from 7.6 ± 0.3 to 9.6 ± 0.3 mm. Additionally, the obtained bacterial endophytes increased the productivity of indole acetic acid (IAA) in broth media from 10 to 60 µg·mL−1 with increasing tryptophan concentration from 1 to 5 mg·mL−1. Bacillus and Brevibacillus strains were frequently isolated from the leaves of both plant species, and had significant positive effects on plant growth and shoot phosphorus (P) and nitrogen (N) contents. Results suggest that these endophytes are good candidates as plant growth promoting inoculants to help reduce chemical input in conventional agricultural practices and increase nutrient uptake and stress resilience in plant species.

Download Full-text

Isolation and Characterization of Bacterial Endophytes from Lycopersicon esculentum Plant and their Plant Growth Promoting Characteristics

Nepal Journal of Biotechnology ◽

10.3126/njb.v2i1.5679 ◽

1970 ◽

Vol 2 (1) ◽

pp. 37-52 ◽

Cited By ~ 19

Author(s):

Hardik A Patel ◽

Rajesh K Patel ◽

Sunil M Khristi ◽

Kruti Parikh ◽

Geetha Rajendran

Keyword(s):

Lycopersicon Esculentum ◽

Plant Growth ◽

Endophytic Bacteria ◽

Growth Promotion ◽

Bacterial Endophytes ◽

Isolation And Characterization ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Different Characteristics

The study was designed to isolate and characterize bacterial endophytes from root and stem of Lycopersicon esculentum plant which was collected form different region of Gujarat. Total 18 isolates of endophytic bacteria were selected in which, all the endophytic bacteria produced one or the other different characteristics involved in plant growth promotion. They either produced phytohormones like indole acetic acid, siderophore, protease, pectinase, organic acid showed antifungal activity, chromium tolerance and solubilized phosphate. Four of the strains among the 18 showed maximum positive results of plant growth promoting regulators (PGPR) test and among them best probable isolate was selected and thus its 16SrDNA was amplified and sequenced. Only HR7 endophyte of tomato turned out to be Pseudomonas aeruginosa. It’s a gram negative coccobacili, sporeforming motile bacilli and show maximum PGPR activity. The results of our present studies indicated that above strains might be endophytic and therefore, were associated with the plant growth. Keywords: Lycopersicon esculentum; endophytic bacteria; PGPR; IAA; 16SrDNA DOI: http://dx.doi.org/10.3126/njb.v2i1.5679 Nepal Journal of Biotechnology Jan.2012, Vol.2(1): 37-52

Download Full-text